0001564590-20-053592 | 10-Q | XBRL Viewer

Balance Sheet Components - Schedule of Accrued Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Compensation	$ 2,544	$ 1,678
Research and development	1,419	702
Property and equipment	488	214
Other	1,370	695
Total accrued and other liabilities	$ 5,821	$ 3,289

CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 188,568	$ 20,607
Short-term investments, available-for-sale	141,191	16,384
Prepaid expenses and other current assets	3,635	474
Total current assets	333,394	37,465
Restricted cash	413	268
Property and equipment, net	9,180	3,080
Operating lease right-of-use assets	8,763	7,144
Other long-term assets	545	455
Total assets	352,295	48,412
Current liabilities
Accounts payable	2,262	1,882
Operating lease liabilities, current portion	1,476	1,516
Preferred stock purchase right liability		1,478
Accrued and other current liabilities	5,821	3,289
Total current liabilities	9,559	8,165
Operating lease liabilities, net of current portion	7,659	5,780
Other long-term liabilities	96	134
Total liabilities	17,314	14,079
Commitments
Convertible preferred stock		59,815
Stockholders’ equity (deficit)
Common stock	3	1
Additional paid-in capital	435,098	1,179
Accumulated other comprehensive loss	4	(2)
Accumulated deficit	(100,124)	(26,660)
Total stockholders’ equity (deficit)	334,981	(25,482)
Total liabilities and stockholders’ equity (deficit)	$ 352,295	$ 48,412

CONDENSED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss		$ (73,464)	$ (10,589)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense		2,657	382
Depreciation and amortization		503	272
Accretion and amortization of investments, net		116
Non-cash lease expense		220	124
Change in fair value of preferred stock purchase right liability	$ (3,383)	40,163	(3,383)
Change in fair value of derivative liability			(858)
Non-cash loss from extinguishment of debt	752		752
Non-cash interest expense on convertible notes	283		472
Others		(15)
Changes in operating assets and liabilities:
Prepaid expenses and other assets		(3,355)	28
Accounts payable and accrued and other liabilities		2,523	1,069
Net cash used in operating activities		(30,652)	(11,731)
Cash flows from investing activities
Purchases of property and equipment		(6,442)	(1,306)
Purchases of short-term investments		(144,916)
Maturities of short-term investments		20,000
Net cash used in investing activities		(131,358)	(1,306)
Cash flows from financing activities
Proceeds from issuance of convertible preferred stock, net of issuance costs		64,321	38,417
Proceeds from initial public offering, net of issuance costs		265,461
Proceeds from stock option exercises		322
Proceeds from early exercise of stock options		12	42
Proceeds from issuance of convertible notes, net of issuance costs			5,986
Net cash provided by financing activities		330,116	44,445
Net increase in cash and cash equivalents		168,106	31,408
Cash, cash equivalents, and restricted cash beginning of period		20,875	7,956
Cash, cash equivalents, and restricted cash end of period	39,364	188,981	39,364
Reconciliation of cash, cash equivalents and restricted cash to the balance sheet:
Cash and cash equivalents	39,095	188,568	39,095
Restricted cash	269	413	269
Total cash, cash equivalents and restricted cash	$ 39,364	188,981	39,364
Non-cash investing activities:
Property and equipment included in accounts payable and accrued liabilities		825	$ 329
Non-cash financing activities:
Deferred offering costs included in accounts payable and accrued liabilities		$ 331

Net Loss Per Share

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Net Loss Per Share

3. Net Loss Per Share

The following tables summarize the computation of the basic and diluted net loss per share (in thousands except share and per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Numerator:
Net loss	$	(13,693	)	$	(2,668	)	$	(73,464	)	$	(10,589	)
Denominator:
Weighted average common shares outstanding		31,095,610			1,718,510			11,620,515			1,706,784
Less: weighted average unvested common stock issued upon early exercise of common stock options		(114,169	)		(160,618	)		(121,188	)		(171,873	)
Less: weighted average unvested founder shares of common stock		—			(29,382	)		—			(113,029	)
Weighted average shares used to compute net loss per share, basic and diluted		30,981,441			1,528,510			11,499,327			1,421,882
Net loss per share, basic and diluted	$	(0.44	)	$	(1.75	)	$	(6.39	)	$	(7.45	)

The following table summarizes the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive:

	As of September 30,
	2020		2019
Common stock options		3,564,980		2,153,688
Unvested common stock upon early exercise of common stock options		107,847		153,528
Convertible preferred stock		—		7,374,034
		3,672,827		9,681,250

Immediately prior to the closing of the Company’s IPO on July 14, 2020, all outstanding shares of the Company’s convertible preferred stock converted into 14,689,215 shares of the Company’s common stock.

Share-Based Compensation

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-Based Compensation

10. Share-Based Compensation

Equity Incentive Plan

The Company’s 2020 Performance Incentive Plan (the “2020 Plan”) which was adopted by the Company’s board of directors in June 2020 and approved by the Company’s stockholders in July 2020, became effective upon the consummation of the IPO. Upon the effectiveness of the 2020 Plan, no further grants may be made under the Company’s 2015 Equity Incentive Plan (the “2015 Plan”). The Company’s 2020 Plan allows for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, stock bonuses, restricted stock, stock units and other forms of awards including cash awards to its officers, directors, employees, consultants and advisors. As of September 30, 2020, there were an aggregate of 2,364,268 shares of common stock issuable upon the exercise of outstanding options under the 2015 Plan. Any options or awards outstanding under the 2015 Plan remain outstanding and effective.

A total of 2,660,371 shares of the Company’s common stock is authorized for issuance with respect to awards granted under the 2020 Plan. The share limit will automatically increase on the first trading day in January of each year (commencing in 2021) by an amount equal to the lesser of (1) 5% of the total number of outstanding shares of the Company’s common stock on the last trading day in December in the prior year, or (2) such lesser number as determined by the Company’s board of directors. Any shares subject to awards granted under the 2020 Plan or the 2015 Plan that are not paid, delivered or exercised before they expire or are canceled or terminated, or otherwise fail to vest, as well as shares used to pay the purchase or exercise price of such awards or related tax withholding obligations, will become available for new award grants under the 2020 Plan. A total of 1,239,532 options had been granted under the 2020 Plan for the three months ended September 30, 2020, and 1,495,314 shares was available for issuance under the 2020 Plan as of September 30, 2020.

The following table summarizes the option activity under the 2020 Plan and 2015 Plan during the nine months ended September 30, 2020:

	Options			Weighted- average exercise price		Weighted- average remaining contractual term (in years)
Outstanding at December 31, 2019		2,329,510		$	3.59	9.6
Granted		1,479,794			16.50
Exercised		(154,114	)		2.17
Forfeited		(90,210	)		9.84
Outstanding at September 30, 2020		3,564,980		$	8.85		9.2
Exercisable at September 30, 2020		419,878		$	4.15		8.6
Vested and expected to vest at September 30, 2020		3,564,980		$	8.85		9.2

The weighted-average grant date fair value of stock option grants was $10.34 per share for the nine months ended September 30, 2020.

Employee Stock Purchase Plan

The Company’s 2020 Employee Stock Purchase Plan (the “ESPP”), which was adopted by the Company’s board of directors in June 2020 and approved by the Company’s stockholders in July 2020, became effective upon the consummation of the IPO. A total of 295,599 shares of the Company’s common stock is initially available for issuance under the ESPP. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for six-month offering periods, and at the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. As of September 30, 2020, no shares had been issued under the ESPP, and the full number of shares authorized under the ESPP Plan was available for issuance purposes upon the effectiveness of the ESPP.

Liability for Early Exercise of Restricted Stock Options

Shares subject to repurchase by the Company were 107,847 shares and 132,249 shares, with the related liability of $0.1 million and $0.1 million recorded under other long-term liabilities in the balance sheets as of September 30, 2020 and December 31, 2019, respectively.

Share-Based Compensation Expense

Share-based compensation expense for the three and nine months ended September 30, 2020 and 2019 were as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development	$	672	$	93	$	1,096	$	156
General and administrative		937		134		1,561		226
Total share-based compensation	$	1,609	$	227	$	2,657	$	382

The total unrecognized compensation cost related to unvested share-based awards was $18.3 million, which is expected to be recognized over a weighted-average remaining service period of 3.4 years as of September 30, 2020.

Subsequently, in October 2020, the Company recorded an estimated shared-based compensation expense of $2.2 million related to the modification of certain stock option granted to its former Chief Financial Officer, Matthew Plunkett, under a Separation and Release Agreement that was executed on October 2, 2020. In addition, the Company recorded severance benefits expense of $0.3 million which is payable in the next 6 months after the termination date.

The fair value of stock options was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Common stock fair value	$	18.86		$	3.89		$	16.50		$	3.92
Risk-free interest rate		0.38	%		1.47	%		0.40	%		1.50	%
Expected volatility		75.17	%		81.10	%		76.08	%		81.12	%
Expected term (in years)		6.0			6.1			6.0			6.1
Expected dividend yield		—	%		—	%		—	%		—	%

Common Stock Reserved for Future Issuance

As of September 30, 2020, the Company had reserved the following shares of common stock for future issuance:

	September 30, 2020
Common stock options granted and outstanding		3,564,980
Reserved for future equity award grants		1,495,314
Reserved for future ESPP issuances		295,599
		5,355,893

Basis of Presentation and Significant Accounting Polices - Additional Information (Details) $ in Millions	Jul. 01, 2020	Sep. 30, 2020	Jul. 31, 2020 USD ($)
Accounting Policies [Line Items]
Reverse stock split, conversion ratio	3.7
Description of the reverse stock split	On July 1, 2020, the Company effected a 1-for-3.7 reverse stock split (the “Reverse Stock Split”) of its issued and outstanding common stock. Accordingly, the conversion ratio for the Company’s outstanding convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split. The par value of the common stock was not adjusted as a result of the Reverse Stock Split. All references to common stock, options to purchase common stock, early exercised options, share data, per share data, convertible preferred stock (to the extent presented on an as-converted to common stock basis) and related information contained in these financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented
Deferred offering costs			$ 4.4
ASU 2016-13
Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Mar. 31, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
ASU 2018-13
Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Mar. 31, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
ASU 2019-12
Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Mar. 31, 2021
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true

Organization and Description of Business - Additional Information (Details) $ / shares in Units, $ in Thousands			3 Months Ended	9 Months Ended
	Jul. 14, 2020 USD ($) $ / shares shares	Jul. 01, 2020 USD ($) shares	Sep. 30, 2020 USD ($) shares	Sep. 30, 2020 USD ($) Segment shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares
Class Of Stock [Line Items]
Number of operating segments \| Segment				1
Shares issued during period \| shares			32,568,332	32,568,332		1,600,601
Proceeds from initial public offering, net of issuance costs				$ 265,461
Accumulated deficit			$ 100,124	100,124		$ 26,660
Cash, cash equivalents restricted cash and short-term investments			$ 330,200	$ 330,200
Proceeds from issuance of convertible notes, net of issuance costs					$ 5,986
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Proceeds from issuance of convertible notes, net of issuance costs		$ 64,400
Temporary equity, shares issued \| shares		27,066,206
IPO
Class Of Stock [Line Items]
Shares issued during period \| shares	16,100,000
Shares issued, price per share \| $ / shares	$ 18.00
Proceeds from initial public offering, net of issuance costs	$ 265,100	$ 265,100
Underwriters Option to Purchase Additional Shares
Class Of Stock [Line Items]
Shares issued during period \| shares	2,100,000
Common Stock
Class Of Stock [Line Items]
Conversion of convertible preferred stock to common stock, Shares \| shares			14,689,215
Common Stock \| IPO
Class Of Stock [Line Items]
Conversion of convertible preferred stock to common stock, Shares \| shares	14,689,215
Proceeds from initial public offering, net of issuance costs	$ 265,100

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Loss Per Share

The following tables summarize the computation of the basic and diluted net loss per share (in thousands except share and per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Numerator:
Net loss	$	(13,693	)	$	(2,668	)	$	(73,464	)	$	(10,589	)
Denominator:
Weighted average common shares outstanding		31,095,610			1,718,510			11,620,515			1,706,784
Less: weighted average unvested common stock issued upon early exercise of common stock options		(114,169	)		(160,618	)		(121,188	)		(171,873	)
Less: weighted average unvested founder shares of common stock		—			(29,382	)		—			(113,029	)
Weighted average shares used to compute net loss per share, basic and diluted		30,981,441			1,528,510			11,499,327			1,421,882
Net loss per share, basic and diluted	$	(0.44	)	$	(1.75	)	$	(6.39	)	$	(7.45	)

Summarizes the Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share

The following table summarizes the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive:

	As of September 30,
	2020		2019
Common stock options		3,564,980		2,153,688
Unvested common stock upon early exercise of common stock options		107,847		153,528
Convertible preferred stock		—		7,374,034
		3,672,827		9,681,250

Stockholders' Deficit

9 Months Ended

Sep. 30, 2020

Equity [Abstract]

Stockholders' Deficit

9. Stockholders’ Deficit

Under the Amended and Restated Certificate of Incorporation dated August 26, 2019, the Company had a total of 126,270,161 shares of capital stock authorized for issuance, consisting of 71,919,982 shares of common stock, par value of $0.0001 per share, and 54,350,179 shares of preferred stock, par value of $0.0001 per share. Of the 54,350,179 shares of preferred stock, 6,170,349 were designated Series A convertible preferred stock and 48,179,830 were designated Series B convertible preferred stock.

In connection with the Reverse Stock Split on July 1, 2020, the Company filed a certificate of amendment to its certificate of incorporation, which provided 100,000,000 authorized shares of common stock with a par value of $0.0001 per share and 54,350,179 authorized shares of preferred stock with a par value of $0.0001 per share.

Series B Convertible Preferred Stock

On August 27, 2019, the Company entered into a Series B Preferred Stock Purchase Agreement (“Stock Purchase Agreement”). The Stock Purchase Agreement contained provisions that obligated the Company to sell, outside of its control, an additional 27,066,206 shares of Series B convertible preferred stock at the Series B Original Issue Price per share, for expected gross proceeds of $64.4 million, upon the achievement of a milestone, or by election of the holders of at least one-third of the Company’s Series B convertible preferred stock at any time prior to the completion of the Company’s initial public offering if the milestone was not achieved (the “Series B Milestone Closing”). If the shares were not purchased prior to the completion of the Company’s initial public offering, then the right to purchase these shares would have automatically expired. In the event that an Initial Series B Closing purchaser, or its affiliates or transferees, failed to purchase their required shares in the Series B Milestone Closing, then all the Series B convertible preferred stock held by such initial Series B purchaser would have been automatically converted into one share of common stock for each ten shares of Series B convertible preferred stock.

On July 1, 2020, the Company completed the Series B Milestone Closing pursuant to a milestone waiver by the holders of the Series B convertible preferred stock, and issued 27,066,206 shares of Series B convertible preferred stock for gross proceeds of $64.4 million. On July 14, 2020, upon the closing of the Company’s IPO, all outstanding shares of the Company’s convertible preferred stock converted into 14,689,215 shares of the Company’s common stock. There were no outstanding shares of the Company’s convertible preferred stock as of September 30, 2020.

The Company determined its obligation to issue additional shares of the Company’s Series B convertible preferred stock in the Series B Milestone Closing represented a freestanding financial instrument that required liability accounting. This freestanding preferred stock purchase right liability was initially recorded at fair value, with fair value changes recognized in the statements of operations and comprehensive loss. At the time the Stock Purchase Agreement was entered into in August 2019, the initial estimated fair value of the preferred stock purchase right liability was $2.8 million, and was revalued at $1.5 million as of December 31, 2019. On July 1, 2020 the preferred stock purchase right liability was revalued at an estimated fair value of $41.6 million and was reclassified to additional paid-in capital upon the exercise of the preferred stock purchase right. The Company recorded the change in the fair value of the Series B convertible preferred stock purchase right liability of $40.2 million as other expense and $3.4 million as other income in the statements of operations and comprehensive loss for the nine months ended September 30, 2020 and 2019, respectively.

Common Stock

As of September 30, 2020, the Company’s amended and restated certificate of incorporation authorized the Company to issue 100,000,000 shares of common stock at a par value of $0.0001 per share.

In conjunction with the Company’s July 2020 IPO closing, the Company issued and sold 16,100,000 shares of its common stock, including 2,100,000 shares pursuant to the full exercise of the underwriters' option to purchase additional shares, at a public offering price of $18.00 per share, for aggregate net proceeds of $265.1 million after deducting underwriting discounts and commissions and other offering costs. In connection with this offering, all outstanding shares of the Company’s convertible preferred stock converted into 14,689,215 shares of common stock.

As of September 30, 2020 and December 31, 2019, 32,568,332 shares and 1,600,601 shares of common stock were issued and outstanding, respectively.

The following is a summary of the rights and privileges of the holders of common stock as of September 30, 2020:

Liquidation Preference: In the event of liquidation, dissolution or winding up, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all debts and other liabilities and the satisfaction of any liquidation preference granted to the holders of any then-outstanding shares of preferred stock.

Dividends: Subject to preferences that may be applicable to any then-outstanding preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by the Board out of legally available funds. As of September 30, 2020, no cash dividends have been declared or paid.

Voting Rights: Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Under the Company’s amended and restated certificate of incorporation and amended and restated bylaws, stockholders will not have cumulative voting rights. Because of this, the holders of a majority of the shares of common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they should so choose.

Rights and Preferences: Holders of common stock have no preemptive, conversion or subscription rights and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock that the Company may designate in the future.

Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended
	Oct. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock available for issuance		5,355,893
Other long-term liabilities		$ 96	$ 134
Unrecognized compensation cost		$ 18,300
Unrecognized compensation cost, expected to be recognized over weighted average remaining service period		3 years 4 months 24 days
Subsequent Event \| Separation and Release Agreement \| Matthew Plunkett
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated share-based compensation expense	$ 2,200
Severance benefits expense	$ 300
Agreement execution date	Oct. 02, 2020
Period in which severance benefits payable after termination date	6 months
Restricted Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to repurchase		107,847	132,249
Other long-term liabilities		$ 100	$ 100
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued		0
Number of common stock available for issuance		295,599
Maximum percentage of employee compensation eligible for plan		15.00%
Offering period		6 months
Commons stock purchase price as percentage of fair value		85.00%
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued		2,364,268
2020 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock authorized for issuance		2,660,371
Increase in share limit as percentage of outstanding shares of common stock on last trading day in prior year		5.00%
Number of awards granted		1,239,532
Number of common stock available for issuance		1,495,314
2020 Plan and 2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value		$ 10.34

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2020	Nov. 09, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-39370
Entity Registrant Name	Nkarta, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-4515206
Entity Address, Address Line One	6000 Shoreline Court
Entity Address, Address Line Two	Suite 102
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	415
Local Phone Number	582-4923
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	NKTX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		32,595,397
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001787400

Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2020

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets are comprised of the following (in thousands):

	September 30, 2020		December 31, 2019
Prepaid expenses	$	389	$	407
Prepaid licenses		376		—
Prepaid insurance		2,278		—
Other current assets		592		67
Total prepaid expenses and other current assets	$	3,635	$	474

Schedule of Property and Equipment, Net

Property and equipment, net is comprised of the following (in thousands):

	September 30, 2020			December 31, 2019
Leasehold improvements	$	3,992		$	287
Furniture and fixtures		322			265
Research equipment		3,839			2,929
Computers and software		95			61
Construction in progress		2,080			183
Total property and equipment		10,328			3,725
Less accumulated depreciation and amortization		(1,148	)		(645	)
Total property and equipment, net	$	9,180		$	3,080

Schedule of Accrued Other Current Liabilities

Accrued other current liabilities are comprised of the following (in thousands):

	September 30, 2020		December 31, 2019
Compensation	$	2,544	$	1,678
Research and development		1,419		702
Property and equipment		488		214
Other		1,370		695
Total accrued and other liabilities	$	5,821	$	3,289

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Collaboration revenue				$ 115
Operating expenses
Research and development	$ 9,828	$ 4,620	$ 24,950	10,535
General and administrative	3,918	1,289	8,560	3,281
Total operating expenses	13,746	5,909	33,510	13,816
Loss from operations	(13,746)	(5,909)	(33,510)	(13,701)
Other income (expense), net:
Change in fair value of preferred stock purchase right liability		3,383	(40,163)	3,383
Change in fair value of derivative liability		858		858
Loss from extinguishment of debt		(752)		(752)
Interest income	206		358	60
Interest expense		(283)		(472)
Other income (expense), net	(153)	35	(149)	35
Total other income (expense), net	53	3,241	(39,954)	3,112
Net loss	(13,693)	(2,668)	(73,464)	(10,589)
Comprehensive loss:
Net loss	(13,693)	(2,668)	(73,464)	(10,589)
Other comprehensive loss	3		6
Comprehensive loss	$ (13,690)	$ (2,668)	$ (73,458)	$ (10,589)
Net loss per share, basic and diluted	$ (0.44)	$ (1.75)	$ (6.39)	$ (7.45)
Weighted average shares used to compute net loss per share, basic and diluted	30,981,441	1,528,510	11,499,327	1,421,882

Basis of Presentation and Significant Accounting Policies

9 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

Basis of Presentation and Significant Accounting Policies

2. Basis of Presentation and Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed financial statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019 have been prepared in accordance with U.S. generally accepted accounting principle (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows.

The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results expected for the full year or any subsequent interim period. The condensed balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2019 included in the Registration Statement on Form S-1 and related Prospectus dated July 9, 2020 filed with the SEC pursuant to Rule 424(b)(4) of the Securities Act of 1933, as amended (“Prospectus”).

Certain prior period amounts reported in the Company’s financial statements and notes thereto have been reclassified to conform to the current period presentation, with no impact on previously reported operating results or financial position.

Reverse Stock Split

On July 1, 2020, the Company effected a 1-for-3.7 reverse stock split (the “Reverse Stock Split”) of its issued and outstanding common stock. Accordingly, the conversion ratio for the Company’s outstanding convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split. The par value of the common stock was not adjusted as a result of the Reverse Stock Split. All references to common stock, options to purchase common stock, early exercised options, share data, per share data, convertible preferred stock (to the extent presented on an as-converted to common stock basis) and related information contained in these financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented.

COVID-19 Pandemic

On March 11, 2020, the World Health Organization declared the outbreak of a novel strain of coronavirus, COVID-19, as a global pandemic, which continued to spread throughout the United States and around the world in the third quarter of 2020. The COVID-19 pandemic is contributing to a general slowdown in the global economy and may affect the Company’s business, results of operations, financial condition, and future strategic plans. The extent of the impact of the COVID-19 pandemic on the Company’s operational and financial performance will depend on certain developments, including the duration and spread of the outbreak, and its impact on the Company’s planned preclinical studies and clinical trials, employees and vendors, all of which are uncertain and cannot be predicted. The Company has taken certain precautionary measures to minimize exposure of our employees to the virus and to comply with directives from public health officials. This includes work from home policies for our employees as well as enhanced safety measures for scientists who are in our labs and manufacturing facility. Some of the third-party vendors that the Company uses have experienced disruptions during this pandemic. At this time, the extent to which the COVID-19 pandemic may impact the Company’s financial condition or results of operations is uncertain and these precautionary measures may negatively impact our productivity, and cause disruptions or delays to our activities and timelines. In response to the pandemic, the Coronavirus Aid, Relief and Economic Security Act (the CARES Act) was signed into law on March 27, 2020. The CARES Act, among other things, includes tax provisions relating to refundable payroll tax credits, deferment of employer’s social security payments, net operating loss utilization and carryback periods, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The CARES Act had no impact on the Company’s income tax provision for the three and nine months ended September 30, 2020. The Company continues to evaluate the impact of the CARES Act on its financial position, results of operations and cash flows. The Company currently does not expect to apply for loans or grants under the CARES Act.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, preclinical studies, fair value of assets and liabilities, convertible preferred stock, share-based compensation and income taxes. Management bases its estimates on historical experience, knowledge of current events and actions it may undertake in the future that management believes to be reasonable under the circumstances. Actual results may differ from these estimates and assumptions.

Deferred Offering Costs

Deferred offering costs consisting of legal, accounting, printing and other fees and costs directly attributable to the IPO are capitalized. Upon the completion of the IPO in July 2020, the total deferred offering costs of $4.4 million were offset against the proceeds from the IPO and reclassified to additional paid in capital on the balance sheets.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the sum of the weighted average number of common shares plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities, which include convertible preferred stock prior to the conversion of such shares to common stock, unvested common stock, and outstanding stock options under the Company’s equity incentive plan, have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.

Recent Accounting Pronouncements

Financial Instruments. 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 based on expected losses to estimate credit losses on certain types of financial instruments, including available-for-sale debt securities. The Company adopted this standard in the first quarter of 2020. The adoption of this standard did not have a material impact on the Company’s financial statements.

Fair Value Measurements. In August 2018, the FASB issued ASU 2018-13—Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurement. The amendments in ASU 2018-13 that relate to changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments in ASU 2018-13 should be applied retrospectively to all periods presented upon their effective date. The Company adopted this standard in the first quarter of 2020. The adoption of this standard did not have a material impact on the Company’s disclosures.

Income Taxes. In December 2019, the FASB issued ASU 2019-12—Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in Topic 740 related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates. This standard is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company will adopt this standard in the first quarter of 2021 and the adoption is not expected to have a material impact on the Company’s financial statements.

There were no other significant updates to the recently issued accounting standards other than as disclosed herewith for the nine months ended September 30, 2020. Although there are several other new accounting pronouncements issued or proposed by the FASB, the Company does not believe any of those accounting pronouncements have had or will have a material impact on its financial position or operating results.

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (13,693)	$ (51,065)	$ (8,706)	$ (2,668)	$ (4,838)	$ (3,083)	$ (73,464)	$ (10,589)
Denominator:
Weighted average common shares outstanding	31,095,610			1,718,510			11,620,515	1,706,784
Less: weighted average unvested common stock issued upon early exercise of common stock options	(114,169)			(160,618)			(121,188)	(171,873)
Less: weighted average unvested founder shares of common stock				(29,382)				(113,029)
Weighted average shares used to compute net loss per share, basic and diluted	30,981,441			1,528,510			11,499,327	1,421,882
Net loss per share, basic and diluted	$ (0.44)			$ (1.75)			$ (6.39)	$ (7.45)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019 have been prepared in accordance with U.S. generally accepted accounting principle (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results expected for the full year or any subsequent interim period. The condensed balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2019 included in the Registration Statement on Form S-1 and related Prospectus dated July 9, 2020 filed with the SEC pursuant to Rule 424(b)(4) of the Securities Act of 1933, as amended (“Prospectus”). Certain prior period amounts reported in the Company’s financial statements and notes thereto have been reclassified to conform to the current period presentation, with no impact on previously reported operating results or financial position.
Reverse Stock Split	Reverse Stock Split On July 1, 2020, the Company effected a 1-for-3.7 reverse stock split (the “Reverse Stock Split”) of its issued and outstanding common stock. Accordingly, the conversion ratio for the Company’s outstanding convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split. The par value of the common stock was not adjusted as a result of the Reverse Stock Split. All references to common stock, options to purchase common stock, early exercised options, share data, per share data, convertible preferred stock (to the extent presented on an as-converted to common stock basis) and related information contained in these financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented.
COVID-19 Pandemic	COVID-19 Pandemic On March 11, 2020, the World Health Organization declared the outbreak of a novel strain of coronavirus, COVID-19, as a global pandemic, which continued to spread throughout the United States and around the world in the third quarter of 2020. The COVID-19 pandemic is contributing to a general slowdown in the global economy and may affect the Company’s business, results of operations, financial condition, and future strategic plans. The extent of the impact of the COVID-19 pandemic on the Company’s operational and financial performance will depend on certain developments, including the duration and spread of the outbreak, and its impact on the Company’s planned preclinical studies and clinical trials, employees and vendors, all of which are uncertain and cannot be predicted. The Company has taken certain precautionary measures to minimize exposure of our employees to the virus and to comply with directives from public health officials. This includes work from home policies for our employees as well as enhanced safety measures for scientists who are in our labs and manufacturing facility. Some of the third-party vendors that the Company uses have experienced disruptions during this pandemic. At this time, the extent to which the COVID-19 pandemic may impact the Company’s financial condition or results of operations is uncertain and these precautionary measures may negatively impact our productivity, and cause disruptions or delays to our activities and timelines. In response to the pandemic, the Coronavirus Aid, Relief and Economic Security Act (the CARES Act) was signed into law on March 27, 2020. The CARES Act, among other things, includes tax provisions relating to refundable payroll tax credits, deferment of employer’s social security payments, net operating loss utilization and carryback periods, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The CARES Act had no impact on the Company’s income tax provision for the three and nine months ended September 30, 2020. The Company continues to evaluate the impact of the CARES Act on its financial position, results of operations and cash flows. The Company currently does not expect to apply for loans or grants under the CARES Act.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, preclinical studies, fair value of assets and liabilities, convertible preferred stock, share-based compensation and income taxes. Management bases its estimates on historical experience, knowledge of current events and actions it may undertake in the future that management believes to be reasonable under the circumstances. Actual results may differ from these estimates and assumptions.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs consisting of legal, accounting, printing and other fees and costs directly attributable to the IPO are capitalized. Upon the completion of the IPO in July 2020, the total deferred offering costs of $4.4 million were offset against the proceeds from the IPO and reclassified to additional paid in capital on the balance sheets.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the sum of the weighted average number of common shares plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities, which include convertible preferred stock prior to the conversion of such shares to common stock, unvested common stock, and outstanding stock options under the Company’s equity incentive plan, have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Financial Instruments. 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 based on expected losses to estimate credit losses on certain types of financial instruments, including available-for-sale debt securities. The Company adopted this standard in the first quarter of 2020. The adoption of this standard did not have a material impact on the Company’s financial statements. Fair Value Measurements. In August 2018, the FASB issued ASU 2018-13—Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurement. The amendments in ASU 2018-13 that relate to changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments in ASU 2018-13 should be applied retrospectively to all periods presented upon their effective date. The Company adopted this standard in the first quarter of 2020. The adoption of this standard did not have a material impact on the Company’s disclosures. Income Taxes. In December 2019, the FASB issued ASU 2019-12—Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in Topic 740 related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates. This standard is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company will adopt this standard in the first quarter of 2021 and the adoption is not expected to have a material impact on the Company’s financial statements. There were no other significant updates to the recently issued accounting standards other than as disclosed herewith for the nine months ended September 30, 2020. Although there are several other new accounting pronouncements issued or proposed by the FASB, the Company does not believe any of those accounting pronouncements have had or will have a material impact on its financial position or operating results.

Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the option activity under the 2020 Plan and 2015 Plan during the nine months ended September 30, 2020:

	Options			Weighted- average exercise price		Weighted- average remaining contractual term (in years)
Outstanding at December 31, 2019		2,329,510		$	3.59	9.6
Granted		1,479,794			16.50
Exercised		(154,114	)		2.17
Forfeited		(90,210	)		9.84
Outstanding at September 30, 2020		3,564,980		$	8.85		9.2
Exercisable at September 30, 2020		419,878		$	4.15		8.6
Vested and expected to vest at September 30, 2020		3,564,980		$	8.85		9.2

Summary of Share-based Compensation Expense

Share-based compensation expense for the three and nine months ended September 30, 2020 and 2019 were as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development	$	672	$	93	$	1,096	$	156
General and administrative		937		134		1,561		226
Total share-based compensation	$	1,609	$	227	$	2,657	$	382

Schedule of Fair Value of Stock Options Estimated on Date of Grant Using Black-Scholes Option Pricing Model

The fair value of stock options was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Common stock fair value	$	18.86		$	3.89		$	16.50		$	3.92
Risk-free interest rate		0.38	%		1.47	%		0.40	%		1.50	%
Expected volatility		75.17	%		81.10	%		76.08	%		81.12	%
Expected term (in years)		6.0			6.1			6.0			6.1
Expected dividend yield		—	%		—	%		—	%		—	%

Summary of Common Stock Reserved for Future Issuance

As of September 30, 2020, the Company had reserved the following shares of common stock for future issuance:

	September 30, 2020
Common stock options granted and outstanding		3,564,980
Reserved for future equity award grants		1,495,314
Reserved for future ESPP issuances		295,599
		5,355,893

CONDENSED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Convertible Preferred Stock
Temporary Equity, Beginning Balance at Dec. 31, 2018						$ 12,709
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2018						6,170,349
Temporary Equity, Ending Balance at Mar. 31, 2019						$ 12,709
Temporary Equity, Ending Balance, Shares at Mar. 31, 2019						6,170,349
Beginning Balance at Dec. 31, 2018	$ (5,396)	$ 1	$ 187	$ (5,584)
Beginning Balance, Shares at Dec. 31, 2018		1,231,840
Vesting of shares of common stock subject to repurchase	20		20
Vesting of shares of common stock subject to repurchase, Shares		134,601
Share-based compensation expense	67		67
Net loss	(3,083)			(3,083)
Ending Balance at Mar. 31, 2019	(8,392)	$ 1	274	(8,667)
Ending Balance, Shares at Mar. 31, 2019		1,366,441
Temporary Equity, Beginning Balance at Dec. 31, 2018						$ 12,709
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2018						6,170,349
Temporary Equity, Ending Balance at Sep. 30, 2019						$ 54,356
Temporary Equity, Ending Balance, Shares at Sep. 30, 2019						24,987,848
Beginning Balance at Dec. 31, 2018	(5,396)	$ 1	187	(5,584)
Beginning Balance, Shares at Dec. 31, 2018		1,231,840
Net loss	(10,589)
Ending Balance at Sep. 30, 2019	(15,573)	$ 1	599	(16,173)
Ending Balance, Shares at Sep. 30, 2019		1,565,859
Temporary Equity, Beginning Balance at Mar. 31, 2019						$ 12,709
Temporary Equity, Beginning Balance, Shares at Mar. 31, 2019						6,170,349
Temporary equity, Beneficial conversion feature upon issuance of convertible promissory notes						$ 261
Temporary Equity, Ending Balance at Jun. 30, 2019						$ 12,970
Temporary Equity, Ending Balance, Shares at Jun. 30, 2019						6,170,349
Beginning Balance at Mar. 31, 2019	(8,392)	$ 1	274	(8,667)
Beginning Balance, Shares at Mar. 31, 2019		1,366,441
Vesting of shares of common stock subject to repurchase	5		5
Vesting of shares of common stock subject to repurchase, Shares		96,030
Share-based compensation expense	88		88
Net loss	(4,838)			(4,838)
Ending Balance at Jun. 30, 2019	(13,137)	$ 1	367	(13,505)
Ending Balance, Shares at Jun. 30, 2019		1,462,471
Temporary equity, reacquisition of beneficial conversion feature upon settlement of promissory notes						$ (145)
Temporary equity, issuance of Series B second tranche convertible preferred stock, net of issuance cost						$ 44,326
Temporary equity, issuance of Series B second tranche convertible preferred stock, net of issuance costs, Shares						18,817,499
Temporary equity, Series B or preferred stock purchase right (liability) reversal upon issuance of convertible preferred stock						$ (2,795)
Temporary Equity, Ending Balance at Sep. 30, 2019						$ 54,356
Temporary Equity, Ending Balance, Shares at Sep. 30, 2019						24,987,848
Vesting of shares of common stock subject to repurchase	5		5
Vesting of shares of common stock subject to repurchase, Shares		97,054
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		6,334
Share-based compensation expense	227		227
Net loss	(2,668)			(2,668)
Ending Balance at Sep. 30, 2019	(15,573)	$ 1	599	(16,173)
Ending Balance, Shares at Sep. 30, 2019		1,565,859
Temporary Equity, Beginning Balance at Dec. 31, 2019	59,815					$ 59,815
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019						27,283,973
Temporary Equity, Ending Balance at Mar. 31, 2020						$ 59,815
Temporary Equity, Ending Balance, Shares at Mar. 31, 2020						27,283,973
Beginning Balance at Dec. 31, 2019	(25,482)	$ 1	1,179	(26,660)	$ (2)
Beginning Balance, Shares at Dec. 31, 2019		1,600,601
Vesting of shares of common stock subject to repurchase	14		14
Vesting of shares of common stock subject to repurchase, Shares		17,494
Issuance of common stock upon exercise of stock option, net of repurchase	1		1
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		2,871
Share-based compensation expense	482		482
Unrealized gain (loss) on short-term investments	(1)				(1)
Net loss	(8,706)			(8,706)
Ending Balance at Mar. 31, 2020	(33,692)	$ 1	1,676	(35,366)	(3)
Ending Balance, Shares at Mar. 31, 2020		1,620,966
Temporary Equity, Beginning Balance at Dec. 31, 2019	59,815					$ 59,815
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019						27,283,973
Temporary Equity, Ending Balance, Shares at Sep. 30, 2020						0
Beginning Balance at Dec. 31, 2019	(25,482)	$ 1	1,179	(26,660)	(2)
Beginning Balance, Shares at Dec. 31, 2019		1,600,601
Net loss	(73,464)
Ending Balance at Sep. 30, 2020	334,981	$ 3	435,098	(100,124)	4
Ending Balance, Shares at Sep. 30, 2020		32,568,332
Temporary Equity, Beginning Balance at Mar. 31, 2020						$ 59,815
Temporary Equity, Beginning Balance, Shares at Mar. 31, 2020						27,283,973
Temporary Equity, Ending Balance at Jun. 30, 2020						$ 59,815
Temporary Equity, Ending Balance, Shares at Jun. 30, 2020						27,283,973
Beginning Balance at Mar. 31, 2020	(33,692)	$ 1	1,676	(35,366)	(3)
Beginning Balance, Shares at Mar. 31, 2020		1,620,966
Vesting of shares of common stock subject to repurchase	12		12
Vesting of shares of common stock subject to repurchase, Shares		19,110
Issuance of common stock upon exercise of stock option, net of repurchase	285		285
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		110,425
Share-based compensation expense	566		566
Unrealized gain (loss) on short-term investments	4				4
Net loss	(51,065)			(51,065)
Ending Balance at Jun. 30, 2020	(83,890)	$ 1	2,539	(86,431)	1
Ending Balance, Shares at Jun. 30, 2020		1,750,501
Temporary equity, issuance of Series B second tranche convertible preferred stock, net of issuance cost						$ 64,321
Temporary equity, issuance of Series B second tranche convertible preferred stock, net of issuance costs, Shares						27,066,206
Reclassification of preferred stock purchase right liability to equity upon issuance of convertible preferred stock						$ 41,641
Temporary equity, conversion of convertible preferred stock to common stock						$ (165,777)
Conversion of convertible preferred stock to common stock, Shares						(54,350,179)
Temporary Equity, Ending Balance, Shares at Sep. 30, 2020						0
Conversion of convertible preferred stock to common stock	165,777	$ 1	165,776
Conversion of convertible preferred stock to common stock, Shares		14,689,215
Issuance of common stock upon initial public offering, net of issuance cost	265,130	$ 1	265,129
Issuance of common stock upon initial public offering, net of issuance cost, Shares		16,100,000
Vesting of shares of common stock subject to repurchase	9		9
Vesting of shares of common stock subject to repurchase, Shares		18,246
Issuance of common stock upon exercise of stock option, net of repurchase	36		36
Issuance of common stock upon exercise of stock option, net of repurchase, Shares		10,370
Share-based compensation expense	1,609		1,609
Unrealized gain (loss) on short-term investments	3				3
Net loss	(13,693)			(13,693)
Ending Balance at Sep. 30, 2020	$ 334,981	$ 3	$ 435,098	$ (100,124)	$ 4
Ending Balance, Shares at Sep. 30, 2020		32,568,332

Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2020

Summary of Fair Value of Financial Instrument

The following tables summarize the fair value of the Company’s financial instruments (in thousands):

			Fair Value Measurements Using
	September 30, 2020		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	186,308	$	186,308	$	—	$	—
Short-term investments:
Corporate debt securities	$	41,957		—	$	41,957		—
Commercial paper		53,922		—		53,922		—
U.S. treasury bills		45,312		—		45,312		—
Total short-term investments		141,191		—		141,191		—
Total	$	327,499	$	186,308	$	141,191	$	—

			Fair Value Measurements Using
	December 31, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Commercial paper	$	2,395	$	—	$	2,395	$	—
Short-term investments:
Corporate debt securities	$	6,027		—	$	6,027		—
Commercial paper		10,357		—		10,357		—
Total short-term investments		16,384		—		16,384		—
Total	$	18,779	$	—	$	18,779	$	—
Liabilities:
Preferred stock purchase right liability	$	1,478	$	—	$	—	$	1,478

Schedule of Change in Preferred Stock Purchase Right Liability

The following table provides the change in preferred stock purchase right liability for the nine months ended September 30, 2020 (in thousands):

	Preferred Stock Purchase Right Liability
Balance, December 31, 2019	$	1,478
Change in fair value of preferred stock purchase right		40,163
Reclassification of preferred stock purchase right liability to equity upon issuance of convertible preferred stock		(41,641	)
Balance, September 30, 2020	$	—

Short-term investments

Schedule of Short-term Investments Accounted as Available-for-sale Securities

The following tables summarize the Company’s short-term investments accounted for as available-for-sale securities as of September 30, 2020 and December 31, 2019 (in thousands):

		September 30, 2020
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	41,959	$	(6	)	$	4	$	41,957
Commercial paper	1 year or less		53,922		—			—		53,922
U.S. treasury bills	1 year or less		45,307		(1	)		6		45,312
Total		$	141,188	$	(7	)	$	10	$	141,191

		December 31, 2019
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	6,029	$	(2	)	$	—	$	6,027
Commercial paper	1 year or less		10,357		—			—		10,357
Total		$	16,386	$	(2	)	$	—	$	16,384

Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

4. Fair Value of Financial Instruments

The following tables summarize the fair value of the Company’s financial instruments (in thousands):

			Fair Value Measurements Using
	September 30, 2020		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	186,308	$	186,308	$	—	$	—
Short-term investments:
Corporate debt securities	$	41,957		—	$	41,957		—
Commercial paper		53,922		—		53,922		—
U.S. treasury bills		45,312		—		45,312		—
Total short-term investments		141,191		—		141,191		—
Total	$	327,499	$	186,308	$	141,191	$	—

			Fair Value Measurements Using
	December 31, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Commercial paper	$	2,395	$	—	$	2,395	$	—
Short-term investments:
Corporate debt securities	$	6,027		—	$	6,027		—
Commercial paper		10,357		—		10,357		—
Total short-term investments		16,384		—		16,384		—
Total	$	18,779	$	—	$	18,779	$	—
Liabilities:
Preferred stock purchase right liability	$	1,478	$	—	$	—	$	1,478

There were no transfers in or out of Level 1 or Level 2 during the three and nine months ended September 30, 2020.

Cash Equivalents and Short-Term Investments

Financial assets measured at fair value on a recurring basis consist of the Company’s cash equivalents and short-term investments. Cash equivalents consisted of money market funds and short-term investments consisted of commercial paper and corporate bonds. The Company obtains pricing information from its investment manager and generally determines the fair value of investment securities using standard observable inputs, including reported trades, broker/dealer quotes, and bids and/or offers.

Investments are classified as Level 1 within the fair value hierarchy if their quoted prices are available in active markets for identical securities. Investments in money market funds of $186.3 million as of September 30, 2020 were classified as Level 1 instruments and were included in cash and cash equivalents.

Investments in marketable securities are valued using Level 2 inputs. Level 2 securities are initially valued at the transaction price and subsequently valued and reported upon utilizing inputs other than quoted prices that are observable either directly or indirectly, such as quotes from third-party pricing vendors. Fair values determined by Level 2 inputs, which utilize data points that are observable such as quoted prices, interest rates and yield curves, require the exercise of judgment and use of estimates, that if changed, could significantly affect the Company’s financial position and results of operations. The marketable securities of $141.2 million as of September 30, 2020 were classified as Level 2 instruments and were included in short-term investments. Accrued interest receivable related to short-term investments were $0.3 million and nil as of September 30, 2020 and 2019, respectively, and included as part of prepaid expenses and other current assets in the balance sheets.

The following tables summarize the Company’s short-term investments accounted for as available-for-sale securities as of September 30, 2020 and December 31, 2019 (in thousands):

		September 30, 2020
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	41,959	$	(6	)	$	4	$	41,957
Commercial paper	1 year or less		53,922		—			—		53,922
U.S. treasury bills	1 year or less		45,307		(1	)		6		45,312
Total		$	141,188	$	(7	)	$	10	$	141,191

		December 31, 2019
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	6,029	$	(2	)	$	—	$	6,027
Commercial paper	1 year or less		10,357		—			—		10,357
Total		$	16,386	$	(2	)	$	—	$	16,384

The Company has classified all of its available-for-sale investment securities as current assets on the balance sheet based on the highly liquid nature of these investment securities and because these investment securities are considered available for use in current operations.

Prior to 2020, the Company followed the guidance in ASC 320 Investments—Debt and Equity Securities in determining whether unrealized losses were other than temporary. The Company adopted Topic 326 on January 1, 2020, and now considers whether unrealized losses have resulted from a credit loss or other factors. The unrealized losses on our available-for-sale securities as of September 30, 2020 and December 31, 2019 were caused by fluctuations in market value and interest rates as a result of the economic environment. The Company concluded that an allowance for credit losses was unnecessary as of September 30, 2020 and that there were no impairments as of December 31, 2019 considered other-than-temporary because the decline in the market value was attributable to changes in market conditions and not credit quality, and that it is neither management’s intention to sell nor is it more likely than not that the Company will be required to sell these investments prior to recovery of their cost basis or recovery of fair value. Unrealized gains and losses are included in accumulated other comprehensive loss.

There was no realized gain or loss on available-for-sale securities in the periods presented. The Company uses the specific identification method to determine the cost basis of investments sold.

Preferred Stock Purchase Right Liability

On July 1, 2020, the Company completed the Series B Milestone Closing and issued 27,066,206 shares of its Series B convertible preferred stock for aggregate gross proceeds of $64.4 million. Accordingly, the preferred stock purchase right liability was revalued at an estimated fair value of $41.6 million and was reclassified to additional paid-in capital on July 1, 2020. See Note 9 for further details on preferred stock purchase right liability.

The estimated fair value of the preferred stock purchase right liability at July 1, 2020 and December 31, 2019 was determined using a valuation model that incorporated the probability of the occurrence of the Series B Milestone Closing in addition to the factors considered at issuance. To determine the fair value of preferred stock purchase right as of July 1, 2020, an intrinsic value model was used. The assumptions used to determine the fair value of the preferred stock purchase right liability as of December 31, 2019 and upon its issuance in August 2019 included an estimated probability of occurrence of the Series B Milestone Closing of 90%, an assumed discount rates of 1.6% and 1.8%, respectively, and an estimated time period the preferred stock purchase right liability would be outstanding of 0.8 years and 1.1 years, respectively. As certain of these inputs are not observable in the market, the preferred stock purchase right liability is classified as a Level 3 instrument.

The following table provides the change in preferred stock purchase right liability for the nine months ended September 30, 2020 (in thousands):

	Preferred Stock Purchase Right Liability
Balance, December 31, 2019	$	1,478
Change in fair value of preferred stock purchase right		40,163
Reclassification of preferred stock purchase right liability to equity upon issuance of convertible preferred stock		(41,641	)
Balance, September 30, 2020	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Fair Value of Financial Instruments - Additional Information (Details) - USD ($)		1 Months Ended		9 Months Ended		12 Months Ended
	Jul. 01, 2020	Dec. 31, 2019	Aug. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value assets transfers from level 1 to level 2				$ 0
Fair value assets transfers from level 2 to level 1				0
Fair value liabilities transfers from level 1 to level 2				0
Fair value liabilities transfers from level 2 to level 1				0
Impairments						$ 0
Realized gain or loss on available-for-sale securities				0
Proceeds from issuance of convertible preferred stock					$ 5,986,000
Preferred stock purchase right liability		$ 1,478,000		41,600,000		$ 1,478,000
Fair value of preferred stock purchase right liability percentage		90.00%	90.00%
Fair value of preferred stock purchase right liability discount rate		1.60%	1.80%
Fair value of preferred stock purchase right liability outstanding term		9 months 18 days	1 year 1 month 6 days
Series B Convertible Preferred Stock
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Temporary equity, shares issued	27,066,206
Proceeds from issuance of convertible preferred stock	$ 64,400,000
Short-term Investments
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Accrued interest receivable				300,000
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments				186,300,000
Significant Other Observable Inputs (Level 2) \| Short-term Investments
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Marketable securities				$ 141,200,000

Stockholders' Deficit - Additional Information (Details)			3 Months Ended		9 Months Ended
	Jul. 14, 2020 USD ($) $ / shares shares	Jul. 01, 2020 USD ($) $ / shares shares	Sep. 30, 2020 Vote $ / shares shares	Sep. 30, 2019 USD ($) shares	Sep. 30, 2020 USD ($) Vote $ / shares shares	Sep. 30, 2019 USD ($) shares	Jun. 30, 2020 shares	Mar. 31, 2020 shares	Dec. 31, 2019 USD ($) shares	Aug. 31, 2019 USD ($)	Aug. 26, 2019 $ / shares shares	Jun. 30, 2019 shares	Mar. 31, 2019 shares	Dec. 31, 2018 shares
Class Of Stock [Line Items]
Capital stock, shares authorized											126,270,161
Common stock, shares authorized		100,000,000	100,000,000		100,000,000						71,919,982
Common stock, par value \| $ / shares		$ 0.0001	$ 0.0001		$ 0.0001						$ 0.0001
Preferred stock, shares authorized		54,350,179									54,350,179
Preferred stock, par value \| $ / shares		$ 0.0001									$ 0.0001
Proceeds from issuance of convertible preferred stock \| $						$ 5,986,000
Estimated fair value of preferred stock purchase right liability \| $		$ 41,600,000							$ 1,478,000	$ 2,800,000
Change in fair value of Series B convertible preferred stock purchase right liability \| $				$ 3,383,000	$ (40,163,000)	$ 3,383,000
Proceeds from initial public offering, net of issuance costs \| $					$ 265,461,000
Shares issued during period			32,568,332		32,568,332				1,600,601
Common stock, shares outstanding			32,568,332		32,568,332				1,600,601
Cash dividends declared or paid \| $					$ 0
Common stock, voting rights					Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors.
Common stock entitled, number of vote for each share \| Vote			1		1
IPO
Class Of Stock [Line Items]
Proceeds from initial public offering, net of issuance costs \| $	$ 265,100,000	$ 265,100,000
Shares issued during period	16,100,000
Underwriters Option to Purchase Additional Shares
Class Of Stock [Line Items]
Shares issued during period	2,100,000
Common Stock
Class Of Stock [Line Items]
Conversion of convertible preferred stock into common stock			14,689,215
Issuance of common stock upon initial public offering, net of issuance cost, Shares			16,100,000
Common Stock \| IPO
Class Of Stock [Line Items]
Conversion of convertible preferred stock into common stock	14,689,215
Issuance of common stock upon initial public offering, net of issuance cost, Shares	16,100,000
Stock public offering price \| $ / shares	$ 18.00
Proceeds from initial public offering, net of issuance costs \| $	$ 265,100,000
Common Stock \| Underwriters Option to Purchase Additional Shares
Class Of Stock [Line Items]
Issuance of common stock upon initial public offering, net of issuance cost, Shares	2,100,000
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares authorized											6,170,349
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares authorized											48,179,830
Number of shares converted into shares		10
Number of shares converted into shares		1
Temporary equity, issuance of Series B second tranche convertible preferred stock, net of issuance costs, Shares		27,066,206
Proceeds from issuance of convertible preferred stock \| $		$ 64,400,000
Series B Convertible Preferred Stock \| Stock Purchase Agreement
Class Of Stock [Line Items]
Number of convertible preferred stock sold and issued during the period		27,066,206
Gross proceed from convertible preferred stock \| $		$ 64,400,000
Convertible Preferred Stock
Class Of Stock [Line Items]
Temporary equity, issuance of Series B second tranche convertible preferred stock, net of issuance costs, Shares			27,066,206	18,817,499
Convertible preferred stock, outstanding			0	24,987,848	0	24,987,848	27,283,973	27,283,973	27,283,973			6,170,349	6,170,349	6,170,349
Convertible Preferred Stock \| Common Stock \| IPO
Class Of Stock [Line Items]
Conversion of convertible preferred stock into common stock	14,689,215

Share-Based Compensation - Summary of Stock Option Activity (Details) - 2020 Plan and 2015 Plan	9 Months Ended	12 Months Ended
	Sep. 30, 2020 $ / shares shares	Dec. 31, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, outstanding beginning balance \| shares	2,329,510
Options, granted \| shares	1,479,794
Options, exercised \| shares	(154,114)
Options, forfeited \| shares	(90,210)
Options, outstanding ending balance \| shares	3,564,980	2,329,510
Options, exercisable \| shares	419,878
Options, vested and expected to vest \| shares	3,564,980
Weighted-average exercise price, outstanding beginning balance \| $ / shares	$ 3.59
Weighted-average exercise price, granted \| $ / shares	16.50
Weighted-average exercise price, exercised \| $ / shares	2.17
Weighted-average exercise price, forfeited \| $ / shares	9.84
Weighted-average exercise price, outstanding ending balance \| $ / shares	8.85	$ 3.59
Weighted-average exercise price, exercisable \| $ / shares	4.15
Weighted-average exercise price, vested and expected to vest \| $ / shares	$ 8.85
Weighted-average remaining contractual term (in years), outstanding balance	9 years 2 months 12 days	9 years 7 months 6 days
Weighted-average remaining contractual term (in years), exercisable	8 years 7 months 6 days
Weighted-average remaining contractual term (in years), vested and expected to vest	9 years 2 months 12 days

Leases - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessee Lease Description [Line Items]
Rent expense		$ 0.5	$ 0.4	$ 1.4	$ 0.8
Cash paid for operating leases		$ 0.4	$ 0.4	$ 1.3	$ 0.8
Weighted-average discount rate		10.00%		10.00%
Operating lease not yet commenced minimum lease payments		$ 4.5		$ 4.5
Corporate Office and Laboratory Space
Lessee Lease Description [Line Items]
Weighted-average remaining lease term		8 years 3 months 18 days		8 years 3 months 18 days
Vivarium
Lessee Lease Description [Line Items]
Weighted-average remaining lease term		6 months		6 months
Office And Laboratory Facilities
Lessee Lease Description [Line Items]
Lease term	8 years
Lease expiration year	2029
Operating lease, existence of option to extend	true
Lessee option to extend description				The lease amendment also includes an extension of the lease term for the existing office and laboratory space beginning on May 1, 2020 through the first quarter of 2029. The lease agreement includes an option to extend the lease for an additional seven-year term.

Balance Sheet Components

9 Months Ended

Sep. 30, 2020

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

5. Balance Sheet Components

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets are comprised of the following (in thousands):

	September 30, 2020		December 31, 2019
Prepaid expenses	$	389	$	407
Prepaid licenses		376		—
Prepaid insurance		2,278		—
Other current assets		592		67
Total prepaid expenses and other current assets	$	3,635	$	474

Property and Equipment, Net

Property and equipment, net is comprised of the following (in thousands):

	September 30, 2020			December 31, 2019
Leasehold improvements	$	3,992		$	287
Furniture and fixtures		322			265
Research equipment		3,839			2,929
Computers and software		95			61
Construction in progress		2,080			183
Total property and equipment		10,328			3,725
Less accumulated depreciation and amortization		(1,148	)		(645	)
Total property and equipment, net	$	9,180		$	3,080

Depreciation and amortization expense were $0.2 million and $0.5 million for the three and nine months ended September 30, 2020, respectively, and $0.1 million and $0.3 million for the three and nine months ended September 30, 2019, respectively.

Accrued and Other Current Liabilities

Accrued other current liabilities are comprised of the following (in thousands):

	September 30, 2020		December 31, 2019
Compensation	$	2,544	$	1,678
Research and development		1,419		702
Property and equipment		488		214
Other		1,370		695
Total accrued and other liabilities	$	5,821	$	3,289

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
2020 (remaining 3 months)	$ 430
2021	1,461
2022	1,452
2023	1,503
2024	1,556
2025 and thereafter	6,981
Total future minimum lease payments	13,383
Less imputed interest	(4,248)
Present value of net minimum lease payments	9,135
Operating lease liabilities:
Current	1,476	$ 1,516
Non-current	7,659	$ 5,780
Total lease liability	$ 9,135

Fair Value of Financial Instruments - Schedule of Short-term Investments Accounted as Available-for-sale Securities (Details) - Short-term Investments - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 141,188	$ 16,386
Available for sale securities, Unrealized Losses	(7)	(2)
Available for sale securities, Unrealized Gains	10
Available for sale securities,Estimated Fair Value	141,191	16,384
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	53,922	10,357
Available for sale securities,Estimated Fair Value	$ 53,922	$ 10,357
Commercial Paper \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	1 year
U.S. Treasury Bills
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 45,307
Available for sale securities, Unrealized Losses	(1)
Available for sale securities, Unrealized Gains	6
Available for sale securities,Estimated Fair Value	$ 45,312
U.S. Treasury Bills \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 41,959	$ 6,029
Available for sale securities, Unrealized Losses	(6)	(2)
Available for sale securities, Unrealized Gains	4
Available for sale securities,Estimated Fair Value	$ 41,957	$ 6,027
Corporate Debt Securities \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	1 year

GSK Collaboration and License Agreement - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Collaboration And License Agreement [Line Items]
Collaboration revenue		$ 115,000
Collaboration and License Agreement \| GSK
Collaboration And License Agreement [Line Items]
Collaboration revenue	$ 0	$ 100,000
Collaboration and License Agreement \| Research and Development \| GSK
Collaboration And License Agreement [Line Items]
Collaboration and license agreement entered month and year	2017-04
Collaboration agreement termination date	Dec. 10, 2018

Commitments and Contingencies - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Liabilities recorded for agreements	$ 0	$ 0
Agreement with Financial Institution [Member]
Loss Contingencies [Line Items]
Letters of credit outstanding amount	$ 400,000
Letter of credit notice period by financial institution before annual expiration date	30 days

Share-Based Compensation - Summary of Common Stock Reserved for Future Issuance (Details)	Sep. 30, 2020 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	5,355,893
Common Stock Options Granted and Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	3,564,980
Reserved for Future Equity Award Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,495,314
Reserved for Future ESPP Issuances
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	295,599

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 10,328	$ 3,725
Less accumulated depreciation and amortization	(1,148)	(645)
Total property and equipment, net	9,180	3,080
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	3,992	287
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	322	265
Research Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	3,839	2,929
Computers and Software
Property Plant And Equipment [Line Items]
Total property and equipment	95	61
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 2,080	$ 183

Net Loss Per Share - Summarizes the Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,672,827	9,681,250
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		7,374,034
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,564,980	2,153,688
Unvested Common Stock Upon Early Exercise of Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	107,847	153,528

Fair Value of Financial Instruments - Summary of Fair Value of Financial Instrument (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets:
Money market funds	$ 186,308
Total short-term investments	141,191	$ 16,384
Total	327,499	18,779
Commercial paper		2,395
Liabilities:
Preferred stock purchase right liability	41,600	1,478
Commercial Paper
Assets:
Total short-term investments	53,922	10,357
U.S. Treasury Bills
Assets:
Total short-term investments	45,312
Corporate Debt Securities
Assets:
Total short-term investments	41,957	6,027
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Money market funds	186,308
Total	186,308
Significant Other Observable Inputs (Level 2)
Assets:
Total short-term investments	141,191	16,384
Total	141,191	18,779
Commercial paper		2,395
Significant Other Observable Inputs (Level 2) \| Commercial Paper
Assets:
Total short-term investments	53,922	10,357
Significant Other Observable Inputs (Level 2) \| U.S. Treasury Bills
Assets:
Total short-term investments	45,312
Significant Other Observable Inputs (Level 2) \| Corporate Debt Securities
Assets:
Total short-term investments	$ 41,957	6,027
Significant Unobservable Inputs (Level 3)
Liabilities:
Preferred stock purchase right liability		$ 1,478

Net Loss Per Share - Additional Information (Details) - Common Stock - shares		3 Months Ended
	Jul. 14, 2020	Sep. 30, 2020
Earnings Per Share Basic [Line Items]
Conversion of convertible preferred stock to common stock, Shares		14,689,215
IPO
Earnings Per Share Basic [Line Items]
Conversion of convertible preferred stock to common stock, Shares	14,689,215

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Prepaid expenses	$ 389	$ 407
Prepaid licenses	376
Prepaid insurance	2,278
Other current assets	592	67
Total prepaid expenses and other current assets	$ 3,635	$ 474