CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net loss	$ (2,214,139)	$ (2,175,258)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	426,939	309,563
Amortization of held-to-maturity securities, net	107,256	32,201
Foreign currency exchange loss (gain), net	10,867	5,148
Changes in operating assets and liabilities:
Interest receivable	102,565	3,981
Accounts receivable	35,258	(106,781)
Income tax receivable	0	6,249
Prepaid research and development	0	83,112
Prepaid expenses and other current assets	(10,529)	5,049
Accounts payable	(292,361)	641,799
Accrued expenses	(326,000)	(96,606)
Deferred research and development obligation	163,799	(117,978)
Net cash used in operating activities	(1,996,345)	(1,409,521)
Cash flows from investing activities
Purchases of held-to-maturity investment securities	(11,652,385)	(13,190,855)
Proceeds from maturities of investment securities	13,350,000	16,197,000
Net cash provided by investing activities	1,697,615	3,006,145
Cash flows from financing activities
Proceeds from exercise of options	175,000	0
Net cash provided by financing activities	175,000	0
Effect of exchange rate changes on cash	(2,983)	(7,177)
Net (decrease) increase in cash and cash equivalents	(126,713)	1,589,447
Cash and cash equivalents at beginning of period	4,823,544	2,386,314
Cash and cash equivalents at end of period	4,696,831	3,975,761
Supplemental cash flow information
Cash received from income tax refund	$ 0	$ 6,249