CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss	$ (7,365,060)	$ (6,569,434)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,264,233	1,034,346
Amortization of held-to-maturity securities, net	282,123	141,362
Foreign currency exchange loss (gain), net	26,317	24,693
Changes in operating assets and liabilities:
Interest receivable	223,306	58,800
Accounts receivable	(141,698)	(110,807)
Income tax receivable	500,616	497,460
Prepaid research and development	0	253,446
Prepaid expenses and other current assets	(141,550)	(164,590)
Accounts payable	(61,651)	429,955
Accrued expenses	50,745	70,541
Deferred research and development obligation	75,211	(47,726)
Net cash used in operating activities	(5,287,408)	(4,381,954)
Cash flows from investing activities
Purchases of held-to-maturity investment securities	(14,677,156)	(37,585,548)
Proceeds from maturities of investment securities	36,761,000	43,953,000
Net cash provided by investing activities	22,083,844	6,367,452
Cash flows from financing activities
Proceeds from exercise of options	230,810	328,590
Net cash provided by financing activities	230,810	328,590
Effect of exchange rate changes on cash	11,791	(38,075)
Net increase in cash and cash equivalents	17,039,037	2,276,013
Cash and cash equivalents at beginning of period	4,823,544	2,386,314
Cash and cash equivalents at end of period	21,862,581	4,662,327
Supplemental cash flow information
Cash received from income tax refund	$ 500,616	$ 506,866