0000950170-23-032298 | 10-K | XBRL Viewer | Kalvista Pharmaceuticals INC

Stock-Based Compensation (Tables)

12 Months Ended

Apr. 30, 2023

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of Fair Value of Share-based Awards Measured with Weighted-Average Assumptions

The fair value of the share-based awards was measured with the following weighted-average assumptions for the fiscal years ended April 30:


	2023	2022	2021
Risk-free interest rate	3.11%	1.08%	0.47%
Expected life of the options	6.25 years	6.25 years	6.25 years
Expected volatility of the underlying stock	92.24%	85.4%	81.7%
Expected dividend rate	0%	0%	0%

Schedule of Stock-Based Compensation Expense

Stock-based compensation was reflected in the Company’s consolidated statement of operations and comprehensive loss as follows (in thousands):


	Year ended April 30,
	2023		2022		2021
Research and development	$	5,384	$	5,189	$	3,174
General and administrative		4,538		5,897		3,944
Total stock-based compensation expense	$	9,922	$	11,086	$	7,118

Summary of Option Activity

A summary of option activity for the year ended April 30, 2023 is presented below:


	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life		Aggregate Intrinsic Value
Outstanding at May 1, 2022		3,593,021		$	16.10		7.26	$	6,430
Options Exercised		(16,938	)		10.00
Options Granted		608,750			9.24
Options Cancelled		(124,658	)		18.93
Outstanding at April 30, 2023		4,060,175		$	15.01		6.65	$	1,668
Exercisable at April 30, 2023		2,801,769		$	14.63		5.99	$	1,548
Vested and expected to vest at April 30, 2023		4,060,175		$	15.01		6.65	$	1,668

Restricted Stock Units

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Activity In Connection With RSU

A summary of activity in connection with our RSUs for the year ended April 30, 2023 is as follows:


	Number of Shares Outstanding	Weighted Average Grant Date Fair Value Per Share
RSU outstanding at April 30, 2022	-	-
RSUs awarded	817,166	8.00
RSUs released	(73,924)	8.43
RSUs forfeited	(1,000)	8.12
RSUs outstanding at April 30, 2023	742,242	7.96

Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Current assets:
Cash and cash equivalents	$ 56,238	$ 30,732
Marketable securities	93,137	135,470
Research and development tax credit receivable	16,568	14,098
Prepaid expenses and other current assets	6,383	13,347
Total current assets	172,326	193,647
Property and equipment, net	2,948	2,178
Right of use assets	7,822	7,862
Other assets	106	193
Total assets	183,202	203,880
Current liabilities:
Accounts payable	4,817	3,638
Accrued expenses	9,128	6,961
Lease liability - current portion	1,087	977
Total current liabilities	15,032	11,576
Long-term liabilities:
Lease liability - net of current portion	7,145	7,211
Total long-term liabilities	7,145	7,211
Commitments and contingencies (Note 9)
Stockholders’ equity
Common stock, $0.001 par value, 100,000,000 authorized Shares issued and outstanding: 34,171,138 and 24,550,748 as of April 30, 2023 and 2022, respectively	34	25
Additional paid-in capital	507,133	439,104
Accumulated deficit	(343,082)	(250,175)
Accumulated other comprehensive loss	(3,060)	(3,861)
Total stockholders’ equity	161,025	185,093
Total liabilities and stockholders’ equity	$ 183,202	$ 203,880

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Apr. 30, 2023	Jun. 28, 2023	Oct. 31, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Apr. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	KALV
Entity Registrant Name	KALVISTA PHARMACEUTICALS, INC.
Entity Central Index Key	0001348911
Current Fiscal Year End Date	--04-30
Entity Well-known Seasoned Issuer	No
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Shell Company	false
Document Annual Report	true
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ
Document Transition Report	false
Entity File Number	001-36830
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-0915291
Entity Address, Address Line One	55 Cambridge Parkway
Entity Address, Address Line Two	Suite 901 East
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	857
Local Phone Number	999-0075
Entity Common Stock, Shares Outstanding		34,233,643
Entity Public Float			$ 119,620,059
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	Information required in responses to Part III of Form 10-K is hereby incorporated by reference to portions of the Registrant’s Proxy Statement for the Annual Meeting of Stockholders to be held in 2023. The Proxy Statement will be filed by the Registrant with the Securities and Exchange Commission no later than 120 days after the end of the Registrant’s fiscal year ended April 30, 2023.
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts

Leases - Summary of Maturity of Undiscounted Payments Due Under Lease Liabilities and Present Value of Liabilities (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2024	$ 1,736
2025	1,844
2026	1,772
2027	1,809
2028	1,848
Thereafter	1,537
Total lease payments	10,546
Less: imputed interest	2,314
Total lease liabilities	8,232
Current lease liabilities	1,087	$ 977
Long-term lease liabilities	$ 7,145	$ 7,211

Summary of Significant Accounting Policies

12 Months Ended

Apr. 30, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2. Summary of Significant Accounting Policies

Principles of consolidation: The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Use of estimates: The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.

Foreign currency: The functional currency of the Company’s United Kingdom (“U.K.”) subsidiary is the British Pound Sterling. Assets and liabilities of the foreign subsidiary are translated using the exchange rate existing on each respective balance sheet date. Revenues and expenses are translated using average exchange rates prevailing throughout the year. The translation adjustments resulting from this process are included as a component of the accumulated other comprehensive loss. In addition, the Company engages in transactions and holds balances denominated and settled in currencies other than the functional currency, and transaction gains or losses are recorded in the consolidated statement of operations.

Segment Reporting: The chief operating decision maker, the CEO, manages the Company’s operations as a single operating segment for the purposes of assessing performance and making operating decisions.

Recent Accounting Pronouncements: In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach on expected losses to estimate credit losses on certain financial instruments, including trade receivables and available-for-sale debt securities. The new guidance is effective for the Company as of May 1, 2023. The adoption of ASU 2016-13 is not expected to have a material impact on the Company’s financial position, results of operations, and cash flows.

Cash and cash equivalents: Cash and cash equivalents consist of bank deposits and money market accounts. Cash equivalents are carried at cost which approximates fair value due to their short-term nature. The Company considers all highly liquid investments with an original maturity of 90 days or less to be cash equivalents.

The Company maintains its cash and cash equivalent balances with financial institutions that management believes are of high credit quality. The Company’s cash and cash equivalent accounts at times may exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company believes it is not exposed to any significant credit risk of cash and cash equivalents.

Research and development tax credit receivable: The research and development tax credit receivable consists of research and development expenses that have been claimed as research and development tax credits in accordance with the relevant U.K. tax legislation. These refundable tax credits are payable to the Company in cash and are carried on the consolidated balance sheet at the amount claimed and expected to be received from the U.K. government within the next 12 months.

Property and equipment: Property and equipment are stated at cost less accumulated depreciation. Expenditures for repairs and maintenance are charged to expense as incurred. Upon retirement or sale, the costs of the assets disposed of and the related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is reflected in the statement of operations. Depreciation is provided using the straight-line method over the estimated useful lives of the assets, which are as follows:


Asset Classification		Estimated Useful Life
Machinery and equipment		1-5 Years
Furniture and fixtures		1-5 Years
Computer equipment		3-4 Years
Leasehold improvements		15 Years or term of lease, if shorter

The Company assesses the impairment of long-lived assets whenever events or changes in circumstances indicate that the carrying value of such assets, or asset groups, may not be recoverable. Whenever events or changes in circumstances suggest

that the carrying amount of long-lived assets may not be recoverable, the future undiscounted cash flows expected to be generated by the asset, or asset groups, from its use or eventual disposition is estimated. If the sum of the expected future undiscounted cash flows is less than the carrying amount of those assets, or asset groups, an impairment loss is recognized based on the excess of the carrying amount over the fair value of the assets, or asset groups.

Revenue recognition: The Company recognizes revenue from research and development arrangements. In accordance with Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers,” revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these goods and services.

Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the good or service either on its own or together with other available resources, and are distinct in the context of the contract, whereby the transfer of the good or service is separately identifiable from other promises in the contract. To the extent a contract includes multiple promised goods and services, the Company must apply judgment to determine whether promised goods and services are capable of being distinct and distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation.

The transaction price is determined based on the consideration to which the Company will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes.

If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation. The consideration to be received is allocated among the separate performance obligations based on relative standalone selling prices.

The Company satisfies performance obligations either over time or at a point in time. Revenue is recognized over time if either: (1) the customer simultaneously receives and consumes the benefits provided by the entity’s performance, (2) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced or (3) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. If the entity does not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring the control of a promised good or service to a customer. ASC 606 requires the Company to select a single revenue recognition method for the performance obligation that faithfully depicts the Company’s performance in transferring control of the goods and services. The guidance allows for two methods to measure progress toward complete satisfaction of a performance obligation, depending on the facts and circumstances:

Output methods - recognize revenue on the basis of direct measurements of the value to the customer of the goods or services transferred to date relative to the remaining goods or services promised under the contract (e.g., surveys of performance completed to date, appraisals of results achieved, milestones reached, time elapsed, and units of produced or units delivered); and

Input methods - recognize revenue on the basis of the entity’s efforts or inputs to the satisfaction of a performance obligation (e.g., resources consumed, labor hours expended, costs incurred, or time elapsed) relative to the total expected inputs to the satisfaction of that performance obligation.

Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company must consider the nature of the intellectual property to which the customer will have rights (i.e., access at a point in time or benefit of intellectual property enhancements over time). The Company recognizes revenue from non-refundable, up-front fees allocated to the license at a point in time/over the period the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress at each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Milestone payments: At the inception of each arrangement that includes development and regulatory milestone payments for promised goods and services, the Company evaluates the circumstances of whether the milestones will be reached and estimates the amount to be included in the transaction price that will not cause a significant revenue reversal.

Up-front payments: Up-front payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Contract balances: The Company recognizes a contract asset when the Company transfers goods or services to a customer before the customer pays consideration or before payment is due, excluding any amounts presented as a receivable (i.e., accounts receivable). A contract asset is an entity’s right to consideration in exchange for goods or services that the entity has transferred to a customer. The contract liabilities (i.e., deferred revenue) primarily relate to contracts where the Company has received payment but has not yet satisfied the related performance obligations. The advance consideration received from customers for research and development services and/or licenses is a contract liability, recorded as deferred revenue, until the underlying performance obligations are transferred to the customer.

Research and development: Research and development costs are expensed as incurred and include, but are not limited to:

•

Employee-related expenses including salaries, benefits, travel, and share-based compensation expense for research and development personnel;

•

Costs associated with preclinical and development activities;

•

Costs associated with regulatory operations.

Costs for certain research and development activities, such as manufacturing development activities and clinical studies are recognized based on the contracted amounts adjusted for the percentage of work completed to date. Payments for these activities are based on the terms of the contractual arrangements, which may differ from the pattern of costs incurred, and are reflected on the consolidated balance sheets as prepaid or accrued expenses. The Company defers and capitalizes non-refundable advance payments made by the Company for research and development activities until the related goods are delivered or the related services are performed.

Income taxes: The Company accounts for income taxes using an asset and liability approach. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The Company evaluates the realizability of its deferred tax assets and establishes a valuation allowance when it is more likely than not that all or a portion of deferred tax assets will not be realized. The Company has provided a full valuation allowance on its deferred tax assets.

Relative to accounting for uncertainties in tax positions, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company records the largest amount of tax benefit with a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, the Company does not recognize a tax benefit in the financial statements.

The Company recognizes interest and penalties related to uncertain tax positions, if any, as a component of income tax expense. As the Company has no uncertain tax positions, there were no interest or penalties charges recognized in the statement of operations for any years.

Stock-based compensation: The Company accounts for stock-based compensation arrangements at fair value. The fair value is recognized over the period during which the recipient is required to provide services (usually the vesting period), on a straight-line basis. Forfeitures are recognized as they are incurred.

Net loss per share: Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the sum of the weighted average number of common shares and the number of potential dilutive common share equivalents outstanding during the period. Potential dilutive common share equivalents consist of the incremental common shares issuable upon the exercise of share options and awards.

Potential dilutive common share equivalents consist of:


	April 30,
	2023		2022		2021
Stock options and awards		5,554,951		3,968,559		2,836,598

In computing diluted earnings per share, common share equivalents are not considered in periods in which a net loss is reported, as the inclusion of the common share equivalents would be anti-dilutive. As a result, there is no difference between the Company’s basic and diluted loss per share in the periods presented.

The weighted average number of common shares used in the basic and diluted net loss per common share calculations includes the weighted-average pre-funded warrants outstanding during the period as they are exercisable at any time for nominal cash consideration.

Fair value measurement: The Company classifies fair value measurements using a three-level hierarchy that prioritizes the inputs used to measure fair value. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1, quoted market prices in active markets for identical assets or liabilities; Level 2, observable inputs other than quoted market prices included in Level 1, such as quoted market prices for similar instruments or for markets that are not active or other inputs that are observable or can be corroborated by observable market data; and Level 3, unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities, including certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. These fair values are obtained from independent pricing services, which utilize Level 1 and Level 2 inputs.

The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of April 30, 2023 and 2022:


	Level 1		Level 2		Level 3		Balance at April 30, 2023
Cash equivalents	$	31,507	$	—	$	—	$	31,507
Marketable securities:
Corporate debt securities		—		77,967		—		77,967
U.S. government agency securities		—		15,170		—		15,170
	$	31,507	$	93,137	$	—	$	124,644


	Level 1		Level 2		Level 3		Balance at April 30, 2022
Cash equivalents	$	13,735	$	—	$	—	$	13,735
Marketable securities:
Corporate debt securities		—		112,005		—		112,005
U.S. government agency securities		—		23,465		—		23,465
	$	13,735	$	135,470	$	—	$	149,205

Income Taxes - Schedule of Reconciliation between Effective Tax Rates and Statutory Rates (Detail)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax benefit at U.S. federal statutory rate	21.00%	21.00%	21.00%
Foreign rate differential	2.80%	(1.50%)	(1.60%)
Nondeductible expenses - UK R&D credit	(7.70%)	(10.60%)	(8.30%)
Other	(0.30%)	(0.80%)	0.40%
Valuation allowance	(15.80%)	(8.10%)	(11.50%)

Stockholder's Equity

12 Months Ended

Apr. 30, 2023

Stockholders' Equity Note [Abstract]

Stockholder's Equity

Note 7. Stockholder’s Equity

Direct Offering

On December 23, 2022, the Company entered into subscription agreements with institutional investors to sell, in a registered direct offering, an aggregate of 9,484,199 shares of common stock at a price of $6.00 per share and pre-funded warrants to purchase up to 182,470 shares of common stock at a price of $5.999 per pre-funded warrant. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, less the $0.001 per share exercise price of each pre-funded warrant. The net proceeds from the registered direct offering, after deducting $0.3 million in expenses, were approximately $57.7 million. The pre-funded warrants do not expire and are exercisable at any time after the issuance date. The Company evaluated the pre-funded warrants for liability or equity classification in accordance with the provisions of ASC Topic 480, Distinguishing Liabilities from Equity, and determined that equity treatment was appropriate because the pre-funded warrants did not meet the definition of liability instruments and met the criteria for permanent equity. As of April 30, 2023, no pre-funded warrants were exercised.

Public Offering of Common Stock

On February 16, 2021, the Company completed a public offering of 6,181,250 shares of its common stock at a price of $36.00 per share, including the underwriters’ full exercise of their option to purchase 806,250 additional shares of common stock. The total net proceeds to the Company were $209.2 million, after deducting underwriting discounts, commissions, and other offering expenses payable by the Company.

ATM Program

On May 21, 2021, the Company filed a shelf registration statement pursuant to which the Company may offer and sell securities having an aggregate public offering price of up to $300 million. In connection with the filing of the Registration Statement, the Company also entered into a sales agreement with a sales agent, pursuant to which the Company may issue and sell shares of its common stock under an at-the-market (the “ATM”) offering program. During the twelve months ended April 30, 2023, the Company did not offer or sell any shares under the sales agreement.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ 0	$ 0	$ 0
Change in valuation allowance	$ 17,000,000.0	17,000,000.0
Amortized period for expenses incurred for research and development in united states	5 years
Amortized period for expenses incurred for research and development outside united states	15 years
Provision for unrecognized tax benefits	$ 0	$ 0	$ 0
U.S. Federal Income Tax [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	6,100,000
U.S. Federal Income Tax [Member] \| Carried Forward Indefinitely [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 16,100,000
U.S. Federal Income Tax [Member] \| Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carry forwards expiration period	2036
State Income Tax [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 16,800,000
State Income Tax [Member] \| Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carry forwards expiration period	2036
U.K. Income Tax [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 120,300,000

Summary of Significant Accounting Policies - Estimated Useful Life of Property and Equipment (Detail)	12 Months Ended
	Apr. 30, 2023
Machinery and Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	1 year
Machinery and Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	5 years
Furniture and Fixtures [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	1 year
Furniture and Fixtures [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	5 years
Computer Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	3 years
Computer Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	4 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of property and equipment	15 Years or term of lease, if shorter

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Cash flows from operating activities:
Net loss	$ (92,907)	$ (82,339)	$ (46,244)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	718	564	537
Stock-based compensation expense	9,922	11,086	7,118
Realized loss (gain) from sale of marketable securities	139	581	(153)
Non-cash operating lease expense	84	179	114
Amortization of premium on available for sale securities	988	2,565	685
Foreign currency exchange loss (gain)	(1,618)	1,552	(574)
Changes in operating assets and liabilities:
Research and development tax credit receivable	(2,316)	(5,201)	7,457
Prepaid expenses and other assets	6,690	(9,280)	(244)
Accounts payable	1,107	1,687	150
Accrued expenses	1,932	472	983
Net cash used in operating activities	(75,261)	(78,134)	(30,171)
Cash flows from investing activities:
Purchases of available for sale securities	(98,246)	(136,920)	(201,210)
Sales and maturities of available for sale securities	140,857	195,711	53,638
Acquisition of property and equipment	(1,196)	(931)	(82)
Net cash provided by (used in) investing activities	41,415	57,860	(147,654)
Cash flows from financing activities:
Issuance of common stock, net of offering expenses	56,582		210,582
Issuance of pre-funded warrants	1,085
Issuance of common stock from equity incentive plans	449	1,581	1,535
Net cash provided by financing activities	58,116	1,581	212,117
Effect of exchange rate changes on cash and cash equivalents	1,236	(1,167)	511
Net (decrease) increase in cash and cash equivalents	25,506	(19,860)	34,803
Cash and cash equivalents, beginning year	30,732	50,592	15,789
Cash and cash equivalents, end of year	56,238	30,732	50,592
Supplemental disclosures of cash flow information:
Right of use assets obtained in exchange for operating lease liabilities	1,192	3,185	$ 4,784
Property and equipment included in accounts payable and accrued expenses:	$ 47	$ 149

Stock-Based Compensation - Summary of Activity In Connection With RSU (Detail) - Restricted Stock Units	12 Months Ended
	Apr. 30, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares Outstanding, RSUs Awarded \| shares	817,166
Number of Shares Outstanding, RSUs Released \| shares	(73,924)
Number of Shares Outstanding, RSUs Forfeited \| shares	(1,000)
Number of Shares Outstanding, RSUs Outstanding Ending Balance. \| shares	742,242
Weighted Average Grant Date Fair Value Per Share, RSUs Awarded \| $ / shares	$ 8.00
Weighted Average Grant Date Fair Value Per Share, RSUs Released \| $ / shares	8.43
Weighted Average Grant Date Fair Value Per Share, RSUs Forfeited \| $ / shares	8.12
Weighted Average Grant Date Fair Value Per Share, RSUs Outstanding Ending Balance \| $ / shares	$ 7.96

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 718	$ 564	$ 537

Other Income (Expenses), Net - Summary of Other Income and Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Other Nonoperating Income (Expense) [Abstract]
R&D tax credit	$ 15,785	$ 15,303
Realized (loss) on sale of securities	(139)	(581)	$ 153
Miscellaneous	(4)	(1)
Other income (expenses), net	$ 15,642	$ 14,721	$ 9,929

Income Taxes (Tables)

12 Months Ended

Apr. 30, 2023

Income Tax Disclosure [Abstract]

Schedule of Components of the Company's Loss Before Income Taxes

The components of the Company’s loss before income taxes for the years ended April 30 consisted of the following (in thousands):


	2023			2022			2021
Domestic	$	(27,437	)	$	(21,145	)	$	(10,909	)
Foreign		(65,470	)		(61,194	)		(35,335	)
	$	(92,907	)	$	(82,339	)	$	(46,244	)

Schedule of Reconciliation between Effective Tax Rates and Statutory Rates

A reconciliation between the effective tax rates and statutory rates for the years ended April 30 is as follows:


	2023			2022			2021
Income tax benefit at U.S. federal statutory rate		21.0	%		21.0	%		21.0	%
Foreign rate differential		2.8	%		(1.5	)%		(1.6	)%
Nondeductible expenses - UK R&D credit		(7.7	)%		(10.6	)%		(8.3	)%
Other		(0.3	)%		(0.8	)%		0.4	%
Valuation allowance		(15.8	)%		(8.1	)%		(11.5	)%
		—			—			—

Schedule of Tax Effect of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities

The tax effect of significant temporary differences representing deferred tax assets and liabilities as of April 30 is as follows (in thousands):


	2023			2022
Deferred tax assets:
Net operating loss (“NOL”) carryforwards	$	35,790		$	23,219
Operating lease liabilities		1,777			1,634
174 Capitalization		3,922			864
Other		5,549			4,072
Subtotal		47,038			29,789
Less: valuation allowance		(45,276	)		(28,212	)
Deferred tax assets, net of valuation allowance		1,762			1,577
Deferred tax liabilities:
Operating lease - Right-of-use assets		(1,693	)		(1,570	)
Other		(69	)		(7	)
Net deferred tax asset	$	—		$	—

Other Income (Expenses), Net (Tables)

12 Months Ended

Apr. 30, 2023

Other Nonoperating Income (Expense) [Abstract]

Summary of Other Income and Expenses

At April 30, 2023 and 2022, other income and expenses consisted of (in thousands):


	2023			2022
R&D tax credit	$	15,785		$	15,303
Realized (loss) on sale of securities		(139	)		(581	)
Miscellaneous		(4	)		(1	)
Other income (expenses), net	$	15,642		$	14,721

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2021
Stock issuance costs	$ 0.3	$ 0.2
At-the-market Sales Agreement [Member]
Stock issuance costs		$ 0.1

Property and Equipment

12 Months Ended

Apr. 30, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment

Note 5. Property and Equipment

At April 30, 2023 and 2022, property and equipment consisted of (in thousands):


	2023			2022
Laboratory equipment	$	2,404		$	2,153
Office equipment		249			148
Furniture & fixtures		398			299
Leasehold improvements		2,855			1,997
Total property and equipment at cost		5,906			4,597
Less: Accumulated depreciation		(2,958	)		(2,419	)
Property and equipment, net	$	2,948		$	2,178

For the years ended April 30, 2023 and 2022, depreciation expense was $0.7 million and $0.6 million, respectively.

Leases (Tables)

12 Months Ended

Apr. 30, 2023

Leases [Abstract]

Summary of Lease Costs

The following table summarizes lease costs included in research and development and general and administrative expense for the years ended April 30, 2023 and 2022 (in thousands):


	2023		2022
Operating lease costs	$	1,806	$	1,743
Short-term lease costs		13		14
Variable lease costs		174		169
Total lease costs	$	1,993	$	1,926

Summary of Maturity of Undiscounted Payments and Future Minimum Payments Due Under Lease Liabilities and Present Value of Liabilities

The following table summarizes the undiscounted payments due under lease liabilities and the present value of those liabilities as of April 30, 2023 (in thousands):


Years ending April 30,	Operating Leases
2024	$	1,736
2025		1,772
2026		1,809
2027		1,848
2028		1,844
Thereafter		1,537
Total lease payments		10,546
Less: imputed interest		2,314
Total lease liabilities		8,232
Current lease liabilities		1,087
Long-term lease liabilities	$	7,145

Summary of Lease Term and Discount Rate

The following table summarizes the lease term and discount rate as of April 30, 2023 and 2022:


	2023			2022
Weighted-average remaining lease term (years)		6.0			6.9
Weighted-average discount rate		9.0	%		9.0	%

Summary of Cash Paid for Amounts Included in Measurement of Lease Liabilities

The following table summarizes the cash paid for amounts included in the measurement of lease liabilities for the years ended April 30, 2023 and 2022 (in thousands):


	2023		2022
Cash paid for amounts included in the measurement of operating lease liabilities	$	1,615	$	1,287

Stock-Based Compensation - Schedule of Fair Value of Share-based Awards Measured with Weighted-Average Assumptions (Detail)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Share-based Payment Arrangement [Abstract]
Risk-free interest rate	3.11%	1.08%	0.47%
Expected life of the options	6 years 3 months	6 years 3 months	6 years 3 months
Expected volatility of the underlying stock	92.24%	85.40%	81.70%
Expected dividend rate	0.00%	0.00%	0.00%

Income Taxes - Schedule of Components of the Company's Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Income Tax Disclosure [Abstract]
Domestic	$ (27,437)	$ (21,145)	$ (10,909)
Foreign	(65,470)	(61,194)	(35,335)
Income before income taxes	$ (92,907)	$ (82,339)	$ (46,244)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8906-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
-Section 25
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=126941158&loc=d3e41242-110953

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-URI https://asc.fasb.org/extlink&oid=126953954&loc=SL114868664-224227

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(8))
-URI https://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-URI https://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8924-108599

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Stock-Based Compensation

12 Months Ended

Apr. 30, 2023

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

Note 8. Stock-Based Compensation

The Company has four plans that provide for equity-based compensation. Two are legacy plans for which no further grants are to be made. As of April 30, 2023, 531,358 stock awards remain available for grant under the 2017 Equity Incentive Plan (“2017 Plan”). There are 6,178,171 shares of the Company’s common stock that are reserved for issuance upon exercise or settlement of stock options or other awards under these four plans. Initial awards generally vest 25% after one year and then ratably on a monthly basis over the next three years. Recurring grants typically vest on a monthly basis over four years. Stock option grants expire after ten years.

In July 2021, the Company approved the 2021 Equity Inducement Plan to reserve 350,000 shares of its common stock to be used exclusively for grants of awards as a material inducement to such individuals' entry into employment with the Company within the meaning of Rule 5635(c)(4) of the Nasdaq Listing Rules. As of April 30, 2023, there were 124,396 shares remaining available to be issued under the 2021 Inducement Plan.

In June 2023, the Company amended and restated the 2021 Equity Inducement Plan (the “Amendment and Restated 2021 Equity Inducement Plan”) to register 500,000 additional shares of its common stock. See Note 14, Subsequent Events.

The Company also has in place the 2017 Employee Stock Purchase Plan (“ESPP”), under which employees have the option to purchase the Company’s common stock at a discount of 15% from the market price during predetermined offering periods each year. There are 974,670 shares available for future issuance under the ESPP as of April 30, 2023.

The Company recognizes stock-based compensation expense over the requisite service period based on the grant date fair value of the award. The Company has elected to use the Black-Scholes option pricing model to determine the fair value of awards granted. The determination of the fair value of stock-based awards utilizing the Black-Scholes model is affected by the share price and a number of assumptions, including expected volatility, expected life, risk-free interest rate and expected dividends. The Company determined the expected volatility by using available historical price information. The expected life of the awards is estimated based on the simplified method. The risk-free interest rate assumption is based on observed interest rates appropriate for the terms of the awards. The dividend yield assumption is based on history and expectation of paying no dividends. Forfeitures have not been material in the periods presented.

The fair value of the share-based awards was measured with the following weighted-average assumptions for the fiscal years ended April 30:


	2023	2022	2021
Risk-free interest rate	3.11%	1.08%	0.47%
Expected life of the options	6.25 years	6.25 years	6.25 years
Expected volatility of the underlying stock	92.24%	85.4%	81.7%
Expected dividend rate	0%	0%	0%

Stock-based compensation was reflected in the Company’s consolidated statement of operations and comprehensive loss as follows (in thousands):


	Year ended April 30,
	2023		2022		2021
Research and development	$	5,384	$	5,189	$	3,174
General and administrative		4,538		5,897		3,944
Total stock-based compensation expense	$	9,922	$	11,086	$	7,118

A summary of option activity for the year ended April 30, 2023 is presented below:


	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life		Aggregate Intrinsic Value
Outstanding at May 1, 2022		3,593,021		$	16.10		7.26	$	6,430
Options Exercised		(16,938	)		10.00
Options Granted		608,750			9.24
Options Cancelled		(124,658	)		18.93
Outstanding at April 30, 2023		4,060,175		$	15.01		6.65	$	1,668
Exercisable at April 30, 2023		2,801,769		$	14.63		5.99	$	1,548
Vested and expected to vest at April 30, 2023		4,060,175		$	15.01		6.65	$	1,668

The weighted-average grant date fair value of stock options granted during the years ended April 30, 2023, 2022 and 2021 was $7.14, $16.98, and $8.24, respectively. The total intrinsic value (the amount by which the fair market value exceeded the exercise price) of stock options exercised during the years ended April 30, 2023, 2022 and 2021 was $0.3 million, $0.8 million and $4.2 million, respectively. The total cash received by the Company as a result of employee stock option exercises during the years ended April 30, 2023, 2022 and 2021 was $0.2 million, $1.4 million, and $1.5 million, respectively.

As of April 30, 2023, there was $12.3 million of unrecognized compensation expense related to unvested awards, which is expected to be recognized over a weighted-average period of 2.2 years.

Restricted Stock Units

During the fiscal year ended April 30, 2023, the Company granted both executives and employees Restricted Stock Units (“RSUs”) from the 2017 Equity Incentive Plan. All RSUs granted are subject to a service condition, and vest over a three or four-year period with equal quarterly vesting.

A summary of activity in connection with our RSUs for the year ended April 30, 2023 is as follows:


	Number of Shares Outstanding	Weighted Average Grant Date Fair Value Per Share
RSU outstanding at April 30, 2022	-	-
RSUs awarded	817,166	8.00
RSUs released	(73,924)	8.43
RSUs forfeited	(1,000)	8.12
RSUs outstanding at April 30, 2023	742,242	7.96

As of April 30, 2023, the unrecognized stock-based compensation cost related to the RSUs was $5.5 million, which is expected to be recognized over a weighted-average period of 2.82 years

In March 2022, the Company granted 360,000 performance-based restricted stock units (“PSUs”) to five executives under the 2017 Equity Incentive Plan with a grant date fair value of $15.39. The performance-based metric for the awards is the success of the Company’s Phase 3 clinical trial of the sebetralstat program. Upon successful completion of the performance metric, 100% of the PSUs will vest in full. As of April 30, 2023 the Company has not recognized any compensation expense related to these awards as the achievement of the Performance Metric is not yet deemed to be probable.

In January 2023, the Company granted 360,000 PSUs to five executives under the 2017 Equity Incentive Plan with a grant date fair value of $6.82. The performance-based metric for the awards is the FDA approval of a New Drug Application for sebetralstat. Upon successful completion of the performance metric, 100% of the PSUs will vest in full. As of April 30, 2023 the Company has not recognized any compensation expense related to these awards as the achievement of the Performance Metric is not yet deemed to be probable.

Leases - Summary of Lease Term and Discount Rate (Detail)	Apr. 30, 2023	Apr. 30, 2022
Lease, Cost [Abstract]
Weighted-average remaining lease term (years)	6 years	6 years 10 months 24 days
Weighted-average discount rate	9.00%	9.00%

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Apr. 30, 2023

Accounting Policies [Abstract]

Principles of Consolidation

Use of Estimates

Foreign Currency

Segment Reporting

Recent Accounting Pronouncements

Cash and Cash Equivalents

Research and Development Tax Credit Receivable

Property and Equipment


Asset Classification		Estimated Useful Life
Machinery and equipment		1-5 Years
Furniture and fixtures		1-5 Years
Computer equipment		3-4 Years
Leasehold improvements		15 Years or term of lease, if shorter

Revenue Recognition

Research and Development

Research and development: Research and development costs are expensed as incurred and include, but are not limited to:

•

Employee-related expenses including salaries, benefits, travel, and share-based compensation expense for research and development personnel;

•

Costs associated with preclinical and development activities;

•

Costs associated with regulatory operations.

Income Taxes

Stock Based Compensation

Net Loss per Share

Potential dilutive common share equivalents consist of:


	April 30,
	2023		2022		2021
Stock options and awards		5,554,951		3,968,559		2,836,598

Fair Value Measurement

The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of April 30, 2023 and 2022:


	Level 1		Level 2		Level 3		Balance at April 30, 2023
Cash equivalents	$	31,507	$	—	$	—	$	31,507
Marketable securities:
Corporate debt securities		—		77,967		—		77,967
U.S. government agency securities		—		15,170		—		15,170
	$	31,507	$	93,137	$	—	$	124,644


	Level 1		Level 2		Level 3		Balance at April 30, 2022
Cash equivalents	$	13,735	$	—	$	—	$	13,735
Marketable securities:
Corporate debt securities		—		112,005		—		112,005
U.S. government agency securities		—		23,465		—		23,465
	$	13,735	$	135,470	$	—	$	149,205

Subsequent Events - Additional Information (Detail)		1 Months Ended	12 Months Ended
Subsequent Events - Additional Information (Detail)	Feb. 16, 2021 shares	Jun. 30, 2023 Executives $ / shares shares	Apr. 30, 2023 $ / shares	Apr. 30, 2022 $ / shares	Apr. 30, 2021 $ / shares
Subsequent Event [Line Items]
Additional shares of common stock to be registered, exclusively for grants of awards as material inducement	806,250
Grant date fair value of performance share units \| $ / shares			$ 7.14	$ 16.98	$ 8.24
2017 Equity Incentive Plan [Member] \| Performance Share Units [Member]
Subsequent Event [Line Items]
Performance share units, vesting term			four quarterly installments beginning in August 2023.
Subsequent Event [Member] \| Amended and Restated 2021 Equity Inducement Plan
Subsequent Event [Line Items]
Additional shares of common stock to be registered, exclusively for grants of awards as material inducement		500,000
Subsequent Event [Member] \| 2017 Equity Incentive Plan [Member] \| Performance Share Units [Member]
Subsequent Event [Line Items]
Number of shares issued		306,667
Number of executives eligible for share grant \| Executives		7
Grant date fair value of performance share units \| $ / shares		$ 9.99

Stock-Based Compensation - Summary of Option Activity (Detail) - USD ($)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022
Share-based Payment Arrangement [Abstract]
Shares, Outstanding Beginning Balance	3,593,021
Shares, Options Exercised	(16,938)
Shares, Options Granted	608,750
Shares, Options Cancelled	(124,658)
Shares, Outstanding Ending Balance	4,060,175	3,593,021
Shares, Exercisable	2,801,769
Shares, Vested and expected to vest	4,060,175
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 16.10
Weighted Average Exercise Price, Options Exercised	10.00
Weighted Average Exercise Price, Options Granted	9.24
Weighted Average Exercise Price, Options Cancelled	18.93
Weighted Average Exercise Price, Outstanding Ending Balance	15.01	$ 16.10
Weighted Average Exercise Price, Exercisable	14.63
Weighted Average Exercise Price, Vested and expected to vest	$ 15.01
Weighted Average Remaining Contractual Life, Outstanding	6 years 7 months 24 days	7 years 3 months 3 days
Weighted Average Remaining Contractual Life, Exercisable	5 years 11 months 26 days
Weighted Average Remaining Contractual Life, Vested and expected to vest	6 years 7 months 24 days
Aggregate Intrinsic Value, Outstanding Beginning Balance	$ 6,430
Aggregate Intrinsic Value, Outstanding Ending Balance	1,668	$ 6,430
Aggregate Intrinsic Value, Exercisable	1,548
Aggregate Intrinsic Value, Vested and expected to vest	$ 1,668

Consolidated Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Operating expenses:
Research and development	$ 80,276,000	$ 70,167,000	$ 41,286,000
General and administrative	30,595,000	26,446,000	16,637,000
Total operating expenses	110,871,000	96,613,000	57,923,000
Operating loss	(110,871,000)	(96,613,000)	(57,923,000)
Other income:
Interest income	2,232,000	1,090,000	903,000
Foreign currency exchange gain (loss)	90,000	(1,537,000)	(847,000)
Other income (expenses), net	15,642,000	14,721,000	9,929,000
Total other income	17,964,000	14,274,000	11,679,000
Loss before income taxes	(92,907,000)	(82,339,000)	(46,244,000)
Income tax (benefit) expense	0	0	0
Net loss	(92,907,000)	(82,339,000)	(46,244,000)
Other comprehensive income (loss):
Foreign currency translation (loss) gain	(604,000)	(1,499,000)	1,076,000
Unrealized holding (loss) gain on marketable securities	1,266,000	(1,511,000)	(473,000)
Reclassification adjustment for realized loss (gain) on available for sale securities included in net loss	139,000	581,000	(153,000)
Total other comprehensive (loss) income:	801,000	(2,429,000)	450,000
Comprehensive loss	$ (92,106,000)	$ (84,768,000)	$ (45,794,000)
Net loss per share, basic	$ (3.33)	$ (3.36)	$ (2.42)
Net loss per share, diluted	$ (3.33)	$ (3.36)	$ (2.42)
Weighted average common shares outstanding, basic	27,890,846	24,473,092	19,094,440
Weighted average common shares outstanding, diluted	27,890,846	24,473,092	19,094,440

Description of Business and Basis of Presentation

12 Months Ended

Apr. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of Business and Basis of Presentation

Note 1. Description of Business and Basis of Presentation

KalVista Pharmaceuticals, Inc. (together with its subsidiaries, the “Company”) is a clinical stage pharmaceutical company focused on the discovery, development and commercialization of small molecule protease inhibitors for diseases with significant unmet need. The Company’s first product candidate is an inhibitor of plasma kallikrein being developed for hereditary angioedema (“HAE”). The Company applies its insights into the chemistry of proteases and, with current programs, the biology of the plasma kallikrein system, to develop small molecule inhibitors with high selectivity, potency and bioavailability that it believes will make them successful treatments for HAE.

In March 2022 the Company initiated the KONFIDENT trial, a phase 3 clinical study to evaluate the safety and efficacy of sebetralstat as a potential on-demand therapy for acute HAE attacks. In October 2022, the Company announced the termination of the phase 2 KOMPLETE study for its potential prophylactic treatment KVD824, due to elevations in liver enzymes observed in patents during the trial. In July 2023, the Company announced that the KONFIDENT trial has reached its targeted enrollment of 114 patients and that data from the trial is expected in the fourth quarter of 2023.

The Company’s headquarters is located in Cambridge, Massachusetts, with additional offices and research activities located in Porton Down, United Kingdom, and Salt Lake City, Utah.

The Company has devoted substantially all of its efforts to research and development, including clinical trials of its product candidate sebetralstat. The Company has not completed the development of any product candidates. Pharmaceutical drug product candidates, like those being developed by the Company, require approvals from the United States (“U.S.”) Food and Drug Administration (“FDA”) or foreign regulatory agencies prior to commercial sales. There can be no assurance that any product candidates will receive the necessary approvals and any failure to receive approval or delay in approval may have a material adverse impact on the Company’s business and financial results. The Company has not yet commenced commercial operations. The Company is subject to a number of risks and uncertainties similar to those of other life science companies developing new products, including, among others, the risks related to the necessity to obtain adequate additional financing, to successfully develop product candidates, to obtain regulatory approval of product candidates, to comply with government regulations, to successfully commercialize its potential products, to the protection of proprietary technology and to the dependence on key individuals.

The Company has funded its operations primarily through the issuance of stock. As of April 30, 2023, the Company had an accumulated deficit of $343.1 million and cash, cash equivalents and marketable securities totaling $149.4 million. The Company’s working capital, primarily cash, cash equivalents and marketable securities, is anticipated to fund the Company’s operations for at least 12 months beyond the date of issuance of the consolidated financial statements.

The Company will need to expend substantial resources for research and development, including costs associated with the clinical testing of its product candidates and will need to obtain additional financing to fund its operations and to conduct trials for its product candidates. The Company will seek to finance future cash needs through equity offerings, future grants, corporate partnerships and product sales.

The Company has never been profitable and has incurred significant operating losses in each year since inception. Cash requirements may vary materially from those now planned because of changes in the Company’s focus and direction of its research and development programs, competitive and technical advances, patent developments, regulatory changes or other developments. Additional financing will be required to continue operations after the Company exhausts its current cash resources and to continue its long-term plans for clinical trials and new product development. There can be no assurance that any such financing can be obtained by the Company, or if obtained, what the terms thereof may be, or that any amount that the Company is able to raise will be adequate to support the Company’s working capital requirements until it achieves profitable operations. If adequate additional working capital is not secured when needed, the Company may be required to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible and/or suspend or curtail planned research programs. Any of these actions could materially harm the Company’s business and prospects.

Summary of Significant Accounting Policies - Schedule of Cash Equivalents and Marketable Securities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 31,507	$ 13,735
Marketable securities	93,137	135,470
Cash equivalents and marketable securities	124,644	149,205
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	31,507	13,735
Cash equivalents and marketable securities	31,507	13,735
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities	93,137	135,470
Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	77,967	112,005
Corporate Debt Securities [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	77,967	112,005
U.S. Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	15,170	23,465
U.S. Government Agency Securities [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 15,170	$ 23,465

Marketable Securities

12 Months Ended

Apr. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Note 3. Marketable Securities

The objectives of the Company’s investment policy are to ensure the safety and preservation of invested funds, as well as to maintain liquidity sufficient to meet cash flow requirements. The Company invests its excess cash in securities issued by financial institutions, commercial companies, and government agencies that management believes to be of high credit quality in order to limit the amount of its credit exposure. The Company has not realized any significant losses from its investments.

The Company classifies all of its investments as available-for-sale. Unrealized gains and losses on investments are recognized in accumulated comprehensive loss, unless an unrealized loss is considered to be other than temporary, in which case the unrealized loss is charged to operations. The Company periodically reviews its investments for other than temporary declines in fair value below cost basis and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company believes the individual unrealized losses represent temporary declines primarily resulting from interest rate changes. Realized gains and losses are included in other income in the consolidated statements of operations and comprehensive loss and are determined using the specific identification method with transactions recorded on a trade date basis.

The following tables summarize the fair value of the Company’s investments by type as of April 30, 2023 and 2022:


	April 30, 2023
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Corporate debt securities	$	77,768	$	367	$	(168	)	$	77,967
Obligations of the U.S. Government and its agencies		15,094		76		—			15,170
Total investments	$	92,862	$	443	$	(168	)	$	93,137


	April 30, 2022
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Corporate debt securities	$	112,997	$	2	$	(994	)	$	112,005
Obligations of the U.S. Government and its agencies		23,602		—		(137	)		23,465
Total investments	$	136,599	$	2	$	(1,131	)	$	135,470

The unrealized losses of the Company’s available-for-sale securities above were a result of market interest rate increases. The Company’s portfolio is structured to allow its short-term debt securities to mature, if needed, to avoid any material losses related to the rise in interest rates. As of April 30, 2023, if the securities are held to maturity, the change in fair value to be recognized as other comprehensive income (loss) is calculated as immaterial.

The following table summarizes the scheduled maturity for the Company’s investments at April 30, 2023:


	April 30,
	2023
Maturing in one year or less	$	81,419
Maturing after one year through two years		7,687
Maturing after two years through four years		4,031
Total investments	$	93,137

Property and Equipment (Tables)

12 Months Ended

Apr. 30, 2023

Property, Plant and Equipment [Abstract]

Components of Property and Equipment

At April 30, 2023 and 2022, property and equipment consisted of (in thousands):


	2023			2022
Laboratory equipment	$	2,404		$	2,153
Office equipment		249			148
Furniture & fixtures		398			299
Leasehold improvements		2,855			1,997
Total property and equipment at cost		5,906			4,597
Less: Accumulated depreciation		(2,958	)		(2,419	)
Property and equipment, net	$	2,948		$	2,178

Leases - Summary of Cash Paid for Amounts Included in Measurement of Lease Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022
Lease, Cost [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 1,615	$ 1,287

Leases

12 Months Ended

Apr. 30, 2023

Leases [Abstract]

Leases

Note 10. Leases

The Company has a lease agreement for approximately 8,300 square feet of space for its headquarters located in Cambridge, Massachusetts that runs through September 2028.

The Company has lease agreements for approximately 13,400 square feet of office and research laboratory space located in Porton Down, United Kingdom that runs through April 2028.

The Company has a lease agreement in Salt Lake City, Utah for approximately 6,200 square feet of office space that commenced in November 2021 that runs through February 2032.

The Company has a lease agreement for approximately 500 square feet of research laboratory space in Cambridge, Massachusetts that commenced in July 2022 with an option to renew annually.

The Company is also party to several operating leases for office and laboratory space as well as certain lab equipment. Total rent expense was $1.8 million, $1.7 million and $0.9 million for the years ended April 30, 2023, 2022 and 2021, respectively and is reflected in general and administrative expenses and research and development expenses as determined by the underlying activities.

Incremental borrowing rate – The Company’s lease agreements do not provide an implicit rate. The Company estimated the incremental borrowing rate based on the rate of interest the Company would have to pay to borrow a similar amount on a collateralized basis over a similar term and economic environment.

Lease and non-lease components – The Company has elected the practical expedient which allows non-lease components to be combined with lease components for all existing asset classes and will therefore include any fixed additional rent amounts in its lease payments. Any variable lease payments are excluded from the lease liability and are recognized in the period incurred.

The following table summarizes lease costs included in research and development and general and administrative expense for the years ended April 30, 2023 and 2022 (in thousands):


	2023		2022
Operating lease costs	$	1,806	$	1,743
Short-term lease costs		13		14
Variable lease costs		174		169
Total lease costs	$	1,993	$	1,926

The following table summarizes the undiscounted payments due under lease liabilities and the present value of those liabilities as of April 30, 2023 (in thousands):


Years ending April 30,	Operating Leases
2024	$	1,736
2025		1,772
2026		1,809
2027		1,848
2028		1,844
Thereafter		1,537
Total lease payments		10,546
Less: imputed interest		2,314
Total lease liabilities		8,232
Current lease liabilities		1,087
Long-term lease liabilities	$	7,145

The following table summarizes the lease term and discount rate as of April 30, 2023 and 2022:


	2023			2022
Weighted-average remaining lease term (years)		6.0			6.9
Weighted-average discount rate		9.0	%		9.0	%

The following table summarizes the cash paid for amounts included in the measurement of lease liabilities for the years ended April 30, 2023 and 2022 (in thousands):


	2023		2022
Cash paid for amounts included in the measurement of operating lease liabilities	$	1,615	$	1,287

Accrued Expenses

12 Months Ended

Apr. 30, 2023

Payables and Accruals [Abstract]

Accrued Expenses

Note 6. Accrued Expenses

At April 30, 2023 and 2022, accrued expenses consisted of (in thousands):


	2023		2022
Accrued research expense	$	3,817	$	2,011
Accrued compensation		4,207		4,168
Accrued professional fees		906		474
Other accrued expenses		198		308
Total accrued expenses	$	9,128	$	6,961

Consolidated Balance Sheets (Parenthetical) - $ / shares	Apr. 30, 2023	Apr. 30, 2022
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	34,171,138	24,550,748
Common stock, shares outstanding	34,171,138	24,550,748

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Apr. 30, 2023

Accounting Policies [Abstract]

Estimated Useful Life of Property and Equipment

Depreciation is provided using the straight-line method over the estimated useful lives of the assets, which are as follows:


Asset Classification		Estimated Useful Life
Machinery and equipment		1-5 Years
Furniture and fixtures		1-5 Years
Computer equipment		3-4 Years
Leasehold improvements		15 Years or term of lease, if shorter

Schedule of Potential Dilutive Common Share Equivalents

Potential dilutive common share equivalents consist of:


	April 30,
	2023		2022		2021
Stock options and awards		5,554,951		3,968,559		2,836,598

Schedule of Cash Equivalents and Marketable Securities Measured at Fair Value

The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of April 30, 2023 and 2022:


	Level 1		Level 2		Level 3		Balance at April 30, 2023
Cash equivalents	$	31,507	$	—	$	—	$	31,507
Marketable securities:
Corporate debt securities		—		77,967		—		77,967
U.S. government agency securities		—		15,170		—		15,170
	$	31,507	$	93,137	$	—	$	124,644


	Level 1		Level 2		Level 3		Balance at April 30, 2022
Cash equivalents	$	13,735	$	—	$	—	$	13,735
Marketable securities:
Corporate debt securities		—		112,005		—		112,005
U.S. government agency securities		—		23,465		—		23,465
	$	13,735	$	135,470	$	—	$	149,205

Property and Equipment - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment at cost	$ 5,906	$ 4,597
Less: Accumulated depreciation	(2,958)	(2,419)
Property and equipment, net	2,948	2,178
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment at cost	2,404	2,153
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment at cost	249	148
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment at cost	398	299
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment at cost	$ 2,855	$ 1,997

Prepaid Expenses and Other Current Assets

12 Months Ended

Apr. 30, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Prepaid Expenses and Other Current Assets

Note 4. Prepaid Expenses and Other Current Assets

At April 30, 2023 and 2022, prepaid expenses and other current assets consisted of (in thousands):


	2023		2022
Prepaid clinical expenses	$	1,724	$	8,404
Other prepaid expenses		2,583		2,234
Interest and other receivables		654		888
VAT receivable		1,422		1,821
Total prepaid expenses and other current assets	$	6,383	$	13,347

Defined Contribution Plans

12 Months Ended

Apr. 30, 2023

Retirement Benefits [Abstract]

Defined Contribution Plans

Note 12. Defined Contribution Plans

Participation in a personal pension plan is available to all U.K. based employees of the Company upon commencement of their employment. Employer contributions are made in accordance with the terms and conditions of the employment contract. Employees of the U.S. parent company are eligible to participate in the Company's 401(k) Plan in which employee contributions on a pre-tax basis are supplemented by matching contributions by the Company. Total employer contributions to both plans for the years ended April 30, 2023, 2022 and 2021 were $0.8 million, $0.6 million and $0.4 million respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Apr. 30, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

At April 30, 2023 and 2022, prepaid expenses and other current assets consisted of (in thousands):


	2023		2022
Prepaid clinical expenses	$	1,724	$	8,404
Other prepaid expenses		2,583		2,234
Interest and other receivables		654		888
VAT receivable		1,422		1,821
Total prepaid expenses and other current assets	$	6,383	$	13,347

Subsequent Events

12 Months Ended

Apr. 30, 2023

Subsequent Events [Abstract]

Subsequent Events

Note 14. Subsequent Events

In June 2023, the Company amended and restated the 2021 Equity Inducement Plan to register 500,000 additional shares of its common stock to be used exclusively for grants of awards as a material inducement to such individuals’ entry into employment with the Company within the meaning of Rule 563(c)(4) of the Nasdaq Listing Rules.

In July 2023, the achievement of the performance metric for certain PSUs granted in June 2023 with performance factors based on full enrollment for the KVD900-301 clinical trial was certified by the Compensation Committee of the Company’s Board of Directors. 306,667 PSUs were granted to seven executives under the 2017 Equity Incentive Plan with a grant date fair value of $9.99 and will vest in four quarterly installments beginning in August 2023.

Marketable Securities - Summary of Scheduled Maturity for Marketable Securities (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 81,419
Maturing after one year through two years	7,687
Maturing after two years through four years	4,031
Total investments	$ 93,137	$ 135,470

Description of Business and Basis of Presentation - Additional Information (Detail) $ in Thousands	Jul. 07, 2023 Patient	Apr. 30, 2023 USD ($)	Apr. 30, 2022 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit		$ 343,082	$ 250,175
Cash, cash equivalents and marketable securities		$ 149,400
Number of patients reached in targeted enrollment \| Patient	114

Marketable Securities - Summary of Fair Value of Company's Investments By Type (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 92,862	$ 136,599
Unrealized Gains	443	2
Unrealized Losses	(168)	(1,131)
Fair Value	93,137	135,470
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	77,768	112,997
Unrealized Gains	367	2
Unrealized Losses	(168)	(994)
Fair Value	77,967	112,005
Obligations of U.S. Government and Its Agencies [Member]
Marketable Securities [Line Items]
Amortized Cost	15,094	23,602
Unrealized Gains	76
Unrealized Losses		(137)
Fair Value	$ 15,170	$ 23,465

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Payables and Accruals [Abstract]
Accrued research expense	$ 3,817	$ 2,011
Accrued compensation	4,207	4,168
Accrued professional fees	906	474
Other accrued expenses	198	308
Total accrued expenses	$ 9,128	$ 6,961

Income Taxes

12 Months Ended

Apr. 30, 2023

Income Tax Disclosure [Abstract]

Income Taxes

Note 11. Income Taxes

The components of the Company’s loss before income taxes for the years ended April 30 consisted of the following (in thousands):


	2023			2022			2021
Domestic	$	(27,437	)	$	(21,145	)	$	(10,909	)
Foreign		(65,470	)		(61,194	)		(35,335	)
	$	(92,907	)	$	(82,339	)	$	(46,244	)

For the years ended April 30, 2023, 2022 and 2021, the Company did not record any U.S. Federal income tax benefit or expense.

A reconciliation between the effective tax rates and statutory rates for the years ended April 30 is as follows:


	2023			2022			2021
Income tax benefit at U.S. federal statutory rate		21.0	%		21.0	%		21.0	%
Foreign rate differential		2.8	%		(1.5	)%		(1.6	)%
Nondeductible expenses - UK R&D credit		(7.7	)%		(10.6	)%		(8.3	)%
Other		(0.3	)%		(0.8	)%		0.4	%
Valuation allowance		(15.8	)%		(8.1	)%		(11.5	)%
		—			—			—

The tax effect of significant temporary differences representing deferred tax assets and liabilities as of April 30 is as follows (in thousands):


	2023			2022
Deferred tax assets:
Net operating loss (“NOL”) carryforwards	$	35,790		$	23,219
Operating lease liabilities		1,777			1,634
174 Capitalization		3,922			864
Other		5,549			4,072
Subtotal		47,038			29,789
Less: valuation allowance		(45,276	)		(28,212	)
Deferred tax assets, net of valuation allowance		1,762			1,577
Deferred tax liabilities:
Operating lease - Right-of-use assets		(1,693	)		(1,570	)
Other		(69	)		(7	)
Net deferred tax asset	$	—		$	—

Management of the Company has determined it is not more likely than not that the Company will recognize the benefits of net deferred tax assets, the majority of which are NOLs, and has provided a valuation allowance for the full amount of deferred tax assets as of April 30, 2023 and 2022, respectively. During the years ended April 30, 2023 and 2022 the valuation allowance changed by $17.0 million. Realization of deferred tax assets is dependent upon the generation of future taxable income.

The ability to utilize the Company’s domestic net operating losses is limited due to changes in ownership as defined by Section 382 of the Internal Revenue Code (the “Code”). Under the provisions of Sections 382 and 383 of the Code, a change of control, as defined in the Code, imposes an annual limitation on the amount of the Company’s net operating loss and tax credit carryforwards, and other tax attributes that can be used to reduce future tax liabilities. The Company determined that ownership changes occurred as a result of public offerings in December 2005, a transaction in November 2016 and a public offering in September 2018. The offering in September of 2018 resulted in an ownership change as of February 2019. The Company believes an ownership change occurred in December 2022 and continues to analyze the impact if any on future NOL utilization.

As of April 30, 2023, the Company has NOL carryforwards for U.S. federal income taxes of $6.1 million that expire in 2036 and $16.1 million that can be carried forward indefinitely. The Company also has NOL carryforwards for state income taxes of $16.8 million that begin to expire in 2036 and NOL carryforwards for U.K. income taxes of $120.3 million that do not expire.

The Company anticipates NOL carryforwards to be limited in the future based on the impact of an ownership change in December 2022. The analysis of which will be final upon the filing of the Company’s 2022 tax return.

The Company recognizes the financial statement effects of a tax position when it becomes more likely than not, based upon the technical merits, that the position will be sustained upon examination. The Company files U.S. Federal tax returns, as well as certain state returns. The Company also files tax returns in the U.K. The Company is subject to U.S. Federal, state, and U.K. income tax examinations by authorities for tax years ending after 2018. There are currently no federal, state, or U.K. audits in process. Tax year 2019 and subsequent years contain matters that could be subject to differing interpretations of the applicable tax laws and regulations as it relates to the amount and or timing of income, deductions, and tax credits. Although the outcome of tax audits is always uncertain, management has analyzed the Company’s tax positions taken for all open tax years and has concluded that no provision for unrecognized tax benefits from uncertain tax positions is required in the Company’s consolidated financial statements for the years ended April 30, 2023 and 2022, respectively.

As part of the Tax Cuts and Jobs Act of 2017 (TCJA), beginning with the Company's 2022 tax year, the Company is required to capitalize research and development expenses, as defined under Internal Revenue Code section 174. For expenses that are incurred for research and development in the U.S., the amounts will be amortized over 5 years, and expenses that are incurred for research and experimentation outside the U.S. will be amortized over 15 years. This provision has not had a significant impact to the consolidated financial statements.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 740
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-Paragraph 2
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Defined Contribution Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
U.K. Employees Personal Pension Plan and U.S. Employees 401(K) Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Total employer contributions	$ 0.8	$ 0.6	$ 0.4

Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022
Other Commitments [Line Items]
Contractual obligation remaining commitments including cancellation provisions	$ 30,500,000
Amounts associated with indemnifications	0
Maximum [Member]
Other Commitments [Line Items]
Royalty payable upon completion of first commercial sale of DME	$ 1,000,000
Royalty payment obligations expiration period	90 days
Indemnification Guarantee [Member]
Other Commitments [Line Items]
Contingent liabilities	$ 0	$ 0

Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions			1 Months Ended			12 Months Ended
	Jun. 30, 2023 shares	Feb. 16, 2021 shares	Jan. 31, 2023 Executives $ / shares shares	Mar. 31, 2022 Executives $ / shares shares	Jul. 31, 2021 shares	Apr. 30, 2023 USD ($) Plan $ / shares shares	Apr. 30, 2022 USD ($) $ / shares	Apr. 30, 2021 USD ($) $ / shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of equity-based compensation plans \| Plan						4
Number of legacy plans \| Plan						2
Option to purchase additional shares of common stock		806,250
Common stock reserved for issuance upon exercise or settlement of stock options or other awards						6,178,171
Weighted-average grant date fair value of stock options granted \| $ / shares						$ 7.14	$ 16.98	$ 8.24
Total intrinsic value of stock options exercised \| $						$ 0.3	$ 0.8	$ 4.2
Total cash received as a result of employee stock option exercises \| $						0.2	$ 1.4	$ 1.5
Unrecognized compensation expense related to unvested awards \| $						$ 12.3
Unrecognized compensation expense related to unvested awards expected to be recognized over a weighted-average period						2 years 2 months 12 days
2017 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock awards, available for grant						531,358
2021 Equity Inducement Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock awards, available for grant						124,396
Shares reserved for grants					350,000
Amendment and Restated 2021 Equity Inducement Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Option to purchase additional shares of common stock	500,000
Stock Options [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Grants vest percentage						25.00%
Recurring grants vesting period						4 years
Scheme termination period						10 years
Stock Options [Member] \| Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock options granted, vesting period						1 year
Stock Options [Member] \| Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock options granted, vesting period						3 years
2017 Employee Stock Purchase Plan (ESPP) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock awards, available for grant						974,670
Percentage of discount for option to purchase common stock						15.00%
Performance Stock Units [Member] \| 2017 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares, Granted			360,000	360,000
Number of executives eligible for share grant \| Executives			5	5
Shares, Grant date fair value \| $ / shares			$ 6.82	$ 15.39
Percentage of share eligible to vest			100.00%	100.00%
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares, Granted						817,166
Shares, Grant date fair value \| $ / shares						$ 8.00
Restricted Stock Units \| 2017 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense related to unvested awards expected to be recognized over a weighted-average period						2 years 9 months 25 days
Unrecognized compensation costs \| $						$ 5.5
Restricted Stock Units \| 2017 Equity Incentive Plan [Member] \| Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock options granted, vesting period						3 years
Restricted Stock Units \| 2017 Equity Incentive Plan [Member] \| Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock options granted, vesting period						4 years

Other Income (Expenses), Net - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Apr. 01, 2023	Mar. 31, 2023	Apr. 30, 2023	Apr. 30, 2022
Research and development tax credit receivable			$ 16,568	$ 14,098
Percentage of reduction in tax credit rates for small medium enterprise	86.00%	130.00%
R&D Credit Carryforward [Member]
Revenue recognized			$ 15,800	$ 15,300

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 22
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Accounting Policies [Abstract]
Uncertain tax positions	$ 0	$ 0	$ 0
Interest or penalties charges recognized	$ 0	$ 0	$ 0

Marketable Securities (Tables)

12 Months Ended

Apr. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Fair Value of Company's Investments By Type

The following tables summarize the fair value of the Company’s investments by type as of April 30, 2023 and 2022:


	April 30, 2023
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Corporate debt securities	$	77,768	$	367	$	(168	)	$	77,967
Obligations of the U.S. Government and its agencies		15,094		76		—			15,170
Total investments	$	92,862	$	443	$	(168	)	$	93,137


	April 30, 2022
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Corporate debt securities	$	112,997	$	2	$	(994	)	$	112,005
Obligations of the U.S. Government and its agencies		23,602		—		(137	)		23,465
Total investments	$	136,599	$	2	$	(1,131	)	$	135,470

Summary of Scheduled Maturity for Marketable Securities

The following table summarizes the scheduled maturity for the Company’s investments at April 30, 2023:


	April 30,
	2023
Maturing in one year or less	$	81,419
Maturing after one year through two years		7,687
Maturing after two years through four years		4,031
Total investments	$	93,137

Leases - Summary of Lease Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022
Lease, Cost [Abstract]
Operating lease costs	$ 1,806	$ 1,743
Short-term lease costs	13	14
Variable lease costs	174	169
Total lease costs	$ 1,993	$ 1,926

Income Taxes - Schedule of Tax Effect of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Deferred tax assets:
Net operating loss ("NOL") carryforwards	$ 35,790	$ 23,219
Operating lease liabilities	1,777	1,634
174 Capitalization	3,922	864
Other	5,549	4,072
Subtotal	47,038	29,789
Less: valuation allowance	(45,276)	(28,212)
Deferred tax assets, net of valuation allowance	1,762	1,577
Deferred tax liabilities:
Operating lease - Right-of-use assets	(1,693)	(1,570)
Other	$ (69)	$ (7)

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Apr. 30, 2020	$ 83,752	$ 18	$ 207,208	$ (121,592)	$ (1,882)
Balance, shares at Apr. 30, 2020		17,845,599
Issuance of common stock, net of issuance costs	208,934	$ 6	208,928
Issuance of common stock, net of issuance costs, shares		6,181,250
Issuance of common shares under an at-the-market sales agreement, net of issuance costs of $132	1,648		1,648
Issuance of common shares under an at-the-market sales agreement, net of issuance costs of $132, shares		97,332
Issuance of common stock from equity incentive plans	1,535		1,535
Issuance of common stock from equity incentive plans, shares		298,350
Stock-based compensation expense	7,118		7,118
Net loss	(46,244)			(46,244)
Foreign currency translation (loss) gain	1,076				1,076
Unrealized holding (loss) gain from marketable securities	(473)				(473)
Reclassification adjustment for realized loss (gain) on marketable securities included in net loss	(153)				(153)
Balance at Apr. 30, 2021	257,193	$ 24	426,437	(167,836)	(1,432)
Balance, shares at Apr. 30, 2021		24,422,531
Issuance of common stock from equity incentive plans	1,582	$ 1	1,581
Issuance of common stock from equity incentive plans, shares		128,217
Stock-based compensation expense	11,086		11,086
Net loss	(82,339)			(82,339)
Foreign currency translation (loss) gain	(1,499)				(1,499)
Unrealized holding (loss) gain from marketable securities	(1,511)				(1,511)
Reclassification adjustment for realized loss (gain) on marketable securities included in net loss	581				581
Balance at Apr. 30, 2022	185,093	$ 25	439,104	(250,175)	(3,861)
Balance, shares at Apr. 30, 2022		24,550,748
Issuance of common stock, net of issuance costs	56,582	$ 9	56,573
Issuance of common stock, net of issuance costs, shares		9,484,199
Issuance of common stock from equity incentive plans	449		449
Issuance of common stock from equity incentive plans, shares		62,267
Release of restricted stock units, shares		73,924
Issuance of pre-funded warrants for the purchase of common stock, net of issuance costs	1,085		1,085
Stock-based compensation expense	9,922		9,922
Net loss	(92,907)			(92,907)
Foreign currency translation (loss) gain	(604)				(604)
Unrealized holding (loss) gain from marketable securities	1,266				1,266
Reclassification adjustment for realized loss (gain) on marketable securities included in net loss	139				139
Balance at Apr. 30, 2023	$ 161,025	$ 34	$ 507,133	$ (343,082)	$ (3,060)
Balance, shares at Apr. 30, 2023		34,171,138

Commitments and Contingencies

12 Months Ended

Apr. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 9. Commitments and Contingencies

Clinical Studies: The Company enters into contractual agreements with contract research organizations in connection with preclinical and toxicology studies and clinical trials. Amounts due under these agreements are invoiced to the Company on predetermined schedules during the course of the studies and clinical trials and are not refundable regardless of the outcome. The Company has a contractual obligation related to the expected future costs to be incurred to complete the ongoing preclinical studies and clinical trials. The remaining commitments, which have cancellation provisions, totaled $30.5 million as of April 30, 2023.

Indemnification: In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnification. The Company’s exposure under these agreements is unknown because it involves future claims that may be made against the Company but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. No amounts associated with such indemnifications have been recorded to date.

Contingencies: From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. There were no contingent liabilities requiring accrual at April 30, 2023 and 2022.

As a result of the terms of grant income received in prior years, upon successful regulatory approval and following the first commercial sale of certain products for DME, the Company will be required to pay royalty fees of up to $1 million within 90 days of the first commercial sale of the product subject to certain caps and follow on payments depending upon commercial success and type of product. Given the stage of development of the current pipeline of products it is not possible to predict with certainty the amount, if any or timing of any such liability.

Leases - Additional Information (Detail) $ in Millions	12 Months Ended
Leases - Additional Information (Detail) $ in Millions	Apr. 30, 2023 USD ($) ft²	Apr. 30, 2022 USD ($)	Apr. 30, 2021 USD ($)
Lessee Lease Description [Line Items]
Lease agreement square feet	500
General and Administrative Expenses and Research and Development Expenses [Member]
Lessee Lease Description [Line Items]
Rent expense \| $	$ 1.8	$ 1.7	$ 0.9
Massachusetts [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	8,300
United Kingdom [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	13,400
Utah [Member]
Lessee Lease Description [Line Items]
Lease agreement square feet	6,200

Other Income (Expenses), Net

12 Months Ended

Apr. 30, 2023

Other Nonoperating Income (Expense) [Abstract]

Other Income (Expenses), Net

Note 13. Other Income (Expenses), Net

At April 30, 2023 and 2022, other income and expenses consisted of (in thousands):


	2023			2022
R&D tax credit	$	15,785		$	15,303
Realized (loss) on sale of securities		(139	)		(581	)
Miscellaneous		(4	)		(1	)
Other income (expenses), net	$	15,642		$	14,721

As of April 30, 2023 and 2022 the Company had research and development tax credits receivable totaling $16.6 million and $14.1 million, respectively. This tax credit is related to a tax scheme for small and medium enterprises in the U.K. as well as an R&D expenditure credit system that allows the Company to file a claim for cash credit in proportion to the Company’s R&D expenditure for the year. This amount is included in other income, as it is a refundable credit that does not depend on the Company’s ongoing tax status or position. The Company recognized $15.8 million and $15.3 million related to these programs in the years ended April 30, 2023 and 2022, respectively.

The Company receives tax credits from the U.K. government based on claims made under the Small Medium Enterprise ("SME) research and development tax relief program. Qualifying expenditures largely relate to research and development activities performed by third parties on the Company's behalf, as well as employment costs for research staff and consumables incurred. The research and development tax credits are recognized when the qualifying expenditure has been incurred and there is reasonable assurance that the reimbursement will be received.

In November 2022, the U.K. government announced changes to the research and development tax credit program. These changes, which include a reduction in tax credit rates for SMEs, were effective on April 1, 2023 and resulted in the credit for the SME R&D regime being reduced from 130% to 86%.

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 9,922	$ 11,086	$ 7,118
Research and Development [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	5,384	5,189	3,174
General and Administrative [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 4,538	$ 5,897	$ 3,944

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Apr. 30, 2023	Apr. 30, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid clinical expenses	$ 1,724	$ 8,404
Other prepaid expenses	2,583	2,234
Interest and other receivables	654	888
VAT receivable	1,422	1,821
Total prepaid expenses and other current assets	$ 6,383	$ 13,347

Stockholder's Equity - Additional Information (Detail) - USD ($)			12 Months Ended
	Dec. 23, 2022	Feb. 16, 2021	Apr. 30, 2023	Apr. 30, 2021	Apr. 30, 2022	May 21, 2021
Class of Warrant or Right [Line Items]
Common stock, per share			$ 0.001		$ 0.001
Option to purchase additional shares of common stock		806,250
Cash proceeds from issuance of common stock		$ 209,200,000	$ 56,582,000	$ 210,582,000
Maximum aggregate public offering price of securities to be issued under shelf registration statement						$ 300,000,000
Common Stock [Member]
Class of Warrant or Right [Line Items]
Common stock, shares issued		6,181,250	9,484,199	6,181,250
Aggregate number of shares to sell under subscription agreements	9,484,199
Common stock, per share		$ 36.00
Price per share under subscription agreements	$ 6.00
Pre-funded Warrants [Member]
Class of Warrant or Right [Line Items]
Price per share under subscription agreements	5.999
Exercise price per share of each pre-funded warrant	$ 0.001
Number of warrants or rights exercised			0
Pre-funded Warrants [Member] \| Maximum [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase shares of common stock	182,470
Direct Offering [Member]
Class of Warrant or Right [Line Items]
Net proceeds from offering, after deducting estimated expenses	$ 57,700,000
Underwriting discounts, commissions, and other offering expenses	$ 300,000

Summary of Significant Accounting Policies - Schedule of Potential Dilutive Common Share Equivalents (Detail) - shares	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Stock Options and Awards [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Number of anti-dilutive potential common share equivalents outstanding	5,554,951	3,968,559	2,836,598

Accrued Expenses (Tables)

12 Months Ended

Apr. 30, 2023

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

At April 30, 2023 and 2022, accrued expenses consisted of (in thousands):


	2023		2022
Accrued research expense	$	3,817	$	2,011
Accrued compensation		4,207		4,168
Accrued professional fees		906		474
Other accrued expenses		198		308
Total accrued expenses	$	9,128	$	6,961