Fair Value Measurements

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

4. FAIR VALUE MEASUREMENTS

The Company’s financial instruments consist of cash and cash equivalents, short-term investments, restricted cash and accounts payable. The carrying amount of cash, restricted cash and accounts payable are each considered a reasonable estimate of fair value due to the short-term maturity.

Assets measured at fair value on a recurring basis were as follows:

Description	September 30, 2023		Quoted Prices (Unadjusted) in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market mutual funds	$	28,375	$	28,375	$	—	$	—
Total cash equivalents	$	28,375	$	28,375	$	—	$	—
Short-term investments:
Commercial paper	$	3,963	$	—	$	3,963	$	—
US Treasury securities		55,267		—		55,267		—
Corporate debt securities		14,957		—		14,957		—
Total short-term investments	$	74,187	$	—	$	74,187	$	—
Total financial assets	$	102,562	$	28,375	$	74,187	$	—

Description	December 31, 2022		Quoted Prices (Unadjusted) in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market mutual funds	$	33,967	$	33,967	$	—	$	—
Total cash equivalents	$	33,967	$	33,967	$	—	$	—
Short-term investments:
Commercial paper	$	57,138	$	—	$	57,138	$	—
US Treasury securities		64,825		—		64,825		—
Corporate debt securities		19,077		—		19,077		—
Total short-term investments	$	141,040	$	—	$	141,040	$	—
Total financial assets	$	175,007	$	33,967	$	141,040	$	—

Short-term securities are valued using models or other valuation methodologies that use Level 2 inputs. These models are primarily industry-standard models that consider various assumptions, including time value, yield curve, volatility factors, default rates, current market and contractual prices for the underlying financial instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace.

There were no transfers between fair value measurement levels during the three and nine months ended September 30, 2023 and 2022.

5. FAIR VALUE MEASUREMENTS

The Company’s financial instruments consist of cash and cash equivalents, short-term investments, restricted cash and accounts payable. The carrying amount of cash, restricted cash and accounts payable are each considered a reasonable estimate of fair value due to the short-term maturity.

Assets measured at fair value on a recurring basis were as follows:

Description	December 31, 2022		Quoted Prices (Unadjusted) in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market mutual funds	$	33,967	$	33,967	$	—	$	—
Total cash equivalents	$	33,967	$	33,967	$	—	$	—
Short-term investments:
Commercial paper	$	57,138	$	—	$	57,138	$	—
US Treasury securities		64,825		—		64,825		—
Corporate debt securities		19,077		—		19,077		—
Total short-term investments	$	141,040	$	—	$	141,040	$	—
Total financial assets	$	175,007	$	33,967	$	141,040	$	—

Description	December 31, 2021		Quoted Prices (Unadjusted) in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market mutual funds	$	108,323	$	108,323	$	—	$	—
Total cash equivalents	$	108,323	$	108,323	$	—	$	—
Short-term investments:
Commercial paper	$	27,992	$	—	$	27,992	$	—
Corporate debt securities		19,499		—		19,499		—
Total short-term investments	$	47,491	$	—	$	47,491	$	—
Total financial assets	$	155,814	$	108,323	$	47,491	$	—

Short-term securities are valued using models or other valuation methodologies that use Level 2 inputs. These models are primarily industry-standard models that consider various assumptions, including time value, yield curve, volatility factors, default rates, current market and contractual prices for the underlying financial instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace.

There were no transfers between fair value measurement levels during the years ended December 31, 2022 and 2021.