Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net Loss	$ (51,660)	$ (89,945)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Non-cash rent expense	(29)	199
Stock based compensation	16,618	29,853
Depreciation and amortization	204	344
Impairment loss on operating lease	136	0
Loss on disposal of fixed assets	94	0
Non-cash goodwill impairment charge	825	0
Amortization of premium / (discount) on available for sale investments	(113)	878
Change in deferred tax liabilities due to acquisition of Novosteo, Inc.	(284)	0
Changes in operating assets and liabilities, net of acquisitions:
Prepaid expenses and other current assets	2,580	(829)
Other assets	194	(155)
Accounts payable	(5,943)	1,356
Accrued expenses and other current liabilities	(6,660)	(4,633)
Net cash used in operating activities	(44,038)	(62,932)
Cash flow from investing activities:
Purchase of investments	(75,021)	(38,789)
Proceeds from maturities of investments	82,493	97,921
Cash acquired from Novosteo, Inc.	10,593	0
Proceeds from disposal of assets	70	0
Purchase of property and equipment	(133)	(180)
Net cash provided by (used in) investing activities	18,002	58,952
Cash flows from financing activities:
Payments of finance leases	(49)	0
Proceeds from issuance of common stock upon exercise of stock options	148	6,808
Proceeds from issuance of common stock	608	0
Proceeds from private placement offering, net of issuance costs	0	0
Net cash provided by financing activities	707	6,808
Effect of exchange rate changes on cash	184	55
Net increase in cash and cash equivalents	(25,145)	2,883
Cash and cash equivalents at beginning of period	69,724	66,841
Cash and cash equivalents at end of period	44,579	69,724
Supplemental disclosures of non-cash information:
Net assets acquired of Novosteo, Inc. in exchange for common stock	16,503	0
Right-of-use assets obtained in exchange for new operating lease liabilities	411	1,254
Right-of-use asset and operating lease liability reduction as a result of lease modification	$ (640)	$ 0