Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flow from operating activities
Net (loss) income	$ (46,408)	$ (71,197)	$ 36,741
Adjustments to reconcile net (loss) income to net cash used in operating activities:
Stock-based compensation expense	9,344	11,324	14,934
Depreciation	6,191	5,165	3,817
Amortization of premiums and discounts on marketable securities	(16)	349	27
Gain on Lease Termination	(2,468)
Change in fair value of common stock and warrants to purchase equity securities		(2,460)	(7,698)
Loss on disposal of fixed assets	377
Changes in operating assets and liabilities:
Related party collaboration receivable	475	7,280	10,484
Prepaid expenses and other assets	(1,967)	1,883	(551)
Operating lease, right-of-use assets	3,462	2,606	(7,592)
Other non-current assets	(152)	69	275
Accounts payable	1,992	(60)	(3,436)
Accrued expenses	(3,148)	(3,335)	(6,480)
Operating lease liabilities	(3,922)	(3,428)	13,439
Deferred revenue	23,731	(1,721)	(150,676)
Net cash used in operating activities	(12,509)	(53,525)	(96,716)
Cash flow from investing activities
Purchases of property and equipment	(2,491)	(1,609)	(12,097)
Purchases of marketable securities	(54,848)	(15,117)	(70,403)
Proceeds from sales and maturities of marketable securities	50,000	82,632	195,495
Net cash (used in) provided by investing activities	(7,339)	65,906	112,995
Cash flow from financing activities
Proceeds from the exercise of stock options	629	28	2,319
Proceeds from the purchase of common stock under ESPP	481	584	844
Net cash provided by financing activities	1,110	612	3,163
Net (decrease) increase in cash and cash equivalents	(18,738)	12,993	19,442
Cash, cash equivalents, and restricted cash beginning of period	119,212	106,219	86,777
Cash, cash equivalents, and restricted cash end of period	100,474	119,212	106,219
Supplemental disclosure of cash and non-cash activities
Operating lease right-of-use assets obtained in exchange for operating lease liabilities		664	10,818
Capital expenditures incurred but not yet paid	$ 14	$ 80	$ 831