Consolidated Statements of Cash Flows - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
| Cash flows from operating activities |
|
|
|
| Net loss |
$ (25,687)
|
$ (68,876)
|
$ (55,350)
|
| Adjustments to reconcile net loss to net cash used in operating activities: |
|
|
|
| Depreciation and amortization |
1,252
|
734
|
726
|
| Amortization of premiums and discounts on marketable securities |
57
|
0
|
(154)
|
| Non-cash lease expense |
1,119
|
1,127
|
1,301
|
| Loss on disposal of property and equipment |
0
|
(52)
|
104
|
| Stock-based compensation expense |
7,720
|
5,422
|
5,161
|
| Non-cash interest expense |
1,012
|
620
|
402
|
| Warrant liabilities revaluation |
2,339
|
10,443
|
857
|
| Loss on extinguishment of debt |
0
|
461
|
0
|
| Net realized losses on marketable securities |
0
|
0
|
(1)
|
| Changes in operating assets and liabilities: |
|
|
|
| Accounts receivable |
(2,690)
|
(2,224)
|
(5,000)
|
| Prepaid expenses, deposits and other assets |
(1,451)
|
(4,418)
|
3,179
|
| Accounts payable |
(219)
|
(57)
|
(600)
|
| Income taxes payable |
601
|
0
|
0
|
| Deferred revenue |
(45,496)
|
94,462
|
337
|
| Accrued expenses and other liabilities |
1,061
|
(2,761)
|
(2,397)
|
| Net cash (used in) provided by operating activities |
(60,382)
|
34,881
|
(51,435)
|
| Cash flows from investing activities |
|
|
|
| Proceeds from maturities of marketable securities |
16,400
|
0
|
16,350
|
| Payment made for investments |
(2,000)
|
0
|
0
|
| Purchases of marketable securities |
(30,455)
|
0
|
(18,188)
|
| Sales of marketable securities |
0
|
0
|
1,992
|
| Purchases of property and equipment |
(1,085)
|
(815)
|
(47)
|
| Proceeds from the sale of property and equipment |
0
|
74
|
122
|
| Net cash used in investing activities |
(17,140)
|
(741)
|
229
|
| Cash flows from financing activities |
|
|
|
| Proceeds from issuance of long-term debt, net of expenses |
0
|
24,736
|
0
|
| Repayments of principal on outstanding debt |
0
|
(19,313)
|
(2,800)
|
| Net proceeds from issuance of common stock- private placement |
0
|
10,268
|
5,715
|
| Issuance costs paid for December 2019 financing |
0
|
(4,381)
|
0
|
| Other financing fees |
0
|
(343)
|
0
|
| Proceeds from exercise of pre-funded and common warrants |
0
|
979
|
70,000
|
| Proceeds from exercise of stock options |
778
|
193
|
150
|
| Proceeds from issuance of common stock under Employee Stock Purchase Plan |
161
|
184
|
28
|
| Net cash provided by financing activities |
52,897
|
14,431
|
105,041
|
| Effect of exchange rate changes on cash |
(3)
|
(58)
|
34
|
| Net change in cash, cash equivalents, and restricted cash |
(24,628)
|
48,513
|
53,869
|
| Cash, cash equivalents, and restricted cash at beginning of period |
140,064
|
91,551
|
37,682
|
| Cash, cash equivalents, and restricted cash at end of period |
115,436
|
140,064
|
91,551
|
| Supplement cash flow information |
|
|
|
| Cash paid for interest |
2,002
|
1,018
|
1,223
|
| Noncash investing and financing activities |
|
|
|
| Cashless warrant exercise |
5,624
|
21,790
|
0
|
| Reclassification of warrant liability to equity upon exercise of warrants |
0
|
1,494
|
0
|
| Fair value of warrants issued in connection with issuance of long-term debt |
0
|
444
|
0
|
| Purchase of property and equipment not yet paid |
224
|
4
|
0
|
| Equity offering costs in accrued liabilities |
24
|
27
|
4,381
|
| Unrealized loss on marketable securities |
(1)
|
0
|
0
|
| Debt issuance costs in accrued liabilities |
0
|
2
|
0
|
| Stock Offering, Excluding At The Market Offering And Private Placement |
|
|
|
| Cash flows from financing activities |
|
|
|
| Net proceeds from issuance of common stock |
0
|
0
|
30,942
|
| At-The-Market Offering |
|
|
|
| Cash flows from financing activities |
|
|
|
| Net proceeds from issuance of common stock |
$ 51,958
|
$ 2,108
|
$ 1,006
|