Organization and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Financial Instruments Measured at Fair Value on Recurring Basis

The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis (in thousands):

			Fair Value Measurements at Reporting Date Using
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of September 30, 2023:
Assets:
Cash equivalents:
Money market funds	$	15,258	$	15,258	$	—	$	—
Total cash equivalents		15,258		15,258		—		—
Short-term investments:
U.S. Treasury securities		70,366		70,366		—		—
U.S. agency bonds		147,405		—		147,405		—
U.S. agency discount notes		4,480		—		4,480		—
Asset-backed securities		4,976		—		4,976		—
Corporate debt securities		1,989		—		1,989		—
Commercial paper		103,344		—		103,344		—
Total short-term investments		332,560		70,366		262,194		—
Restricted cash:
Money market account		816		816		—		—
Total restricted cash		816		816		—		—
Total assets measured at fair value on a recurring basis	$	348,634	$	86,440	$	262,194	$	—

			Fair Value Measurements at Reporting Date Using
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of December 31, 2022:
Assets:
Cash equivalents:
Money market funds	$	12,697	$	12,697	$	—	$	—
Total cash equivalents		12,697		12,697		—		—
Short-term investments:
U.S. Treasury securities		63,016		63,016		—		—
U.S. agency bonds		67,020		—		67,020		—
U.S. agency discount notes		4,334		—		4,334		—
Corporate debt securities		1,970		—		1,970		—
Commercial paper		139,250		—		139,250		—
Total short-term investments		275,590		63,016		212,574		—
Restricted cash:
Money market account		816		816		—		—
Total restricted cash		816		816		—		—
Total assets measured at fair value on a recurring basis	$	289,103	$	76,529	$	212,574	$	—

Reconciliation of Cash and Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the accompanying balance sheets that sum to the amounts shown in the statements of cash flows (in thousands):

	September 30, 2023		December 31, 2022
Cash and cash equivalents	$	17,152	$	51,426
Restricted cash		816		816
Total cash and cash equivalents and restricted cash	$	17,968	$	52,242

Summary of Short-Term Investments

The following tables summarize short-term investments (in thousands):

	As of September 30, 2023
	Amortized		Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
U.S. Treasury securities	$	70,561	$	—	$	(195	)	$	70,366
U.S. agency bonds		148,222		—		(817	)		147,405
U.S. agency discount notes		4,481		—		(1	)		4,480
Asset-backed securities		5,026		—		(50	)		4,976
Corporate debt securities		1,993		—		(4	)		1,989
Commercial paper		103,451		2		(109	)		103,344
Total	$	333,734	$	2	$	(1,176	)	$	332,560

	As of December 31, 2022
	Amortized		Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
U.S. Treasury securities	$	63,675	$	—	$	(659	)	$	63,016
U.S. agency bonds		67,421		—		(401	)		67,020
U.S. agency discount notes		4,321		13		—			4,334
Corporate debt securities		1,975		—		(5	)		1,970
Commercial paper		139,733		26		(509	)		139,250
Total	$	277,125	$	39	$	(1,574	)	$	275,590

The amortized cost and estimated fair value in the tables above exclude $1.7 million and $0.7 million of accrued interest receivable as of September 30, 2023 and December 31, 2022, respectively. Accrued interest receivable is included in prepaid expenses and other current assets in the accompanying balance sheets.

Schedule of Contractual Maturities of Available-for-sale Debt Securities

Contractual maturities of available-for-sale debt securities are as follows (in thousands):

	As of September 30, 2023
	Due in 1 Year or Less		Due Between 1 and 2 Years
U.S. Treasury securities	$	15,489	$	54,877
U.S. agency bonds		66,206		81,199
U.S. agency discount notes		4,480		—
Asset-backed securities		4,976		—
Corporate debt securities		1,989		—
Commercial paper		103,344		—
Total	$	196,484	$	136,076

	As of December 31, 2022
	Due in 1 Year or Less		Due Between 1 and 2 Years
U.S. Treasury securities	$	57,369	$	5,647
U.S. agency bonds		37,202		29,818
U.S. agency discount notes		4,334		—
Corporate debt securities		—		1,970
Commercial paper		139,250		—
Total	$	238,155	$	37,435

Schedule of Available-for-Sale Debt Securities in an Unrealized Loss Position

	As of December 31, 2022
	Less Than 12 Months					12 Months or Longer					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities	$	15,566	$	(82	)	$	47,450	$	(577	)	$	63,016	$	(659	)
U.S. agency bonds		67,020		(401	)		—		—			67,020		(401	)
Corporate debt securities		1,970		(5	)		—		—			1,970		(5	)
Commercial paper		118,840		(509	)		—		—			118,840		(509	)
Total	$	203,396	$	(997	)	$	47,450	$	(577	)	$	250,846	$	(1,574	)

There were no available-for-sale debt securities in a continuous unrealized loss position for 12 months or longer at September 30, 2023.

Summary of Potentially Dilutive Shares Not Included in the Calculation of Net Loss Per Share

Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares):

	September 30,
	2023		2022
Common stock options		8,495,581		7,591,570
Unvested common stock		17,003		112,325
Employee stock purchase plan shares		23,172		12,965
Total potentially dilutive shares		8,535,756		7,716,860