Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 33,006	$ 82,233
Marketable securities	100,011	46,620
Restricted cash - current	10	10
Receivable from collaboration partner and contract asset - related party	6,755	4,587
Research and development tax incentive receivable, net		1,429
Prepaid expenses and other current assets	5,529	2,624
Total current assets	145,311	137,503
Property and equipment, net	1,681	861
Restricted cash - noncurrent	450	450
Operating lease right-of-use asset	6,042
Deferred tax asset	1,433	658
Total assets	154,917	139,472
Current liabilities:
Accounts payable	2,790	5,711
Payable to collaboration partner - related party	1,262	1,061
Accrued expenses and other payables	12,360	11,163
Deferred revenue - related party - current	17,738	8,223
Operating lease liability - current	1,256
Total current liabilities	35,406	26,158
Long-term debt, net	9,794
Deferred revenue - related party - noncurrent	23,792
Operating lease liability - noncurrent	5,961
Deferred rent		799
Total liabilities	74,953	26,957
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock, $0.00001 par value, 10,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.00001 par value, 90,000,000 shares authorized; 27,217,649 and 23,187,219 shares issued and outstanding as of December 31, 2019 and December 31, 2018, respectively
Additional paid-in capital	297,846	253,222
Accumulated other comprehensive loss	(221)	(233)
Accumulated deficit	(217,661)	(140,474)
Total stockholders’ equity	79,964	112,515
Total liabilities and stockholders’ equity	$ 154,917	$ 139,472