Significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2020

Significant accounting policies

Schedule of reconciliation of cash, cash equivalents and restricted cash

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

	December 31, 2020		December 31, 2019
Cash and cash equivalents	$	67,782	$	43,514
Restricted cash		241		35,748
Total cash, cash equivalents and restricted cash	$	68,023	$	79,262

Schedule of financial instruments measured at fair value on a recurring basis

The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands):

	December 31, 2020
Description	Total		Level 1		Level 2		Level 3
Financial assets
Cash equivalents	$	65,610	$	60,611	$	4,999	$	—
Short-term investments	$	73,444	$	—	$	73,444	$	—
Long-term investments	$	5,995	$	—	$	5,995	$	—
Total financial assets	$	145,049	$	60,611	$	84,438	$	—
	December 31, 2019
Description	Total		Level 1		Level 2		Level 3
Financial assets
Cash equivalents	$	77,176	$	75,678	$	1,498	$	—
Short-term investments		31,992		—		31,992		—
Total financial assets	$	109,168	$	75,678	$	33,490	$	—
Derivative liability	$	450		—		—	$	450

Schedule of derivative liability reconciliation

The following table represents a reconciliation of the derivative liability recorded in connection with the issuance of the 2019 Notes (in thousands):

January 1, 2019	$	—
Fair value recognized upon issuance of 2019 Notes		247
Fair value adjustment		641
Derivative liability extinguished upon conversion		(438)
December 31, 2019	$	450
Fair value adjustment		1,313
Derivative liability extinguished upon conversion		(1,763)
December 31, 2020	$	—

Schedule of cash, cash equivalents and investments

Cash, cash equivalents, restricted cash and investments consist of the following (in thousands):

	December 31, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash, cash equivalents & restricted cash:
Cash and money market accounts	$	63,024	$	—	$	—	$	63,024
Corporate bonds, agency bonds and commercial paper (due within 90 days)		4,998		1		—		4,999
Total cash, cash equivalents & restricted cash:	$	68,022	$	1	$	—	$	68,023
Investments:
Corporate bonds, agency bonds and commercial paper (due within 1 year)	$	73,389	$	55	$	—	$	73,444
Corporate bonds, agency bonds and commercial paper (due between 1 and 5 years)		5,998		—		(3)		5,995
Total investments	$	79,387	$	55	$	(3)	$	79,439
Total cash, cash equivalents, restricted cash and investments	$	147,409	$	56	$	(3)	$	147,462

	December 31, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash, cash equivalents & restricted cash:
Cash and money market accounts	$	77,764	$	—	$	—	$	77,764
Corporate bonds, agency bonds and commercial paper (due within 90 days)		1,498	$	—	$	—	$	1,498
Total cash, cash equivalents & restricted cash:	$	79,262	$	—	$	—	$	79,262
Investments:
Corporate bonds and commercial paper (due within 1 year)	$	31,979	$	14	$	—	$	31,993
Total investments	$	31,979	$	14	$	—	$	31,993
Total cash, cash equivalents, restricted cash and investments	$	111,241	$	14	$	—	$	111,255

Schedule of estimated useful lives of the assets

Laboratory equipment	5 years
Furniture	5 years
Computer equipment	3 years
Leasehold improvements	Lesser of useful life or life of lease