Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (13,007,344)	$ (11,660,022)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation expense	15,443	18,595
Stock-based compensation expense	1,035,834	1,457,720
Loss on disposition of property and equipment	0	37,478
Non-cash interest expense	221,209	259,865
Non-cash gain on change in fair value of warrant liability	(236,400)	0
Amortization of premium/discount on marketable investment securities	(164,306)	(198,344)
Changes in operating assets and liabilities:
Accrued interest income	21,992	(15,447)
Litigation insurance recovery	0	3,319,927
Prepaid and other current assets	(25,774)	(111,886)
Accounts payable	510,961	73,210
Litigation settlement payable	0	(4,250,000)
Accrued expenses	(37,832)	(1,009,921)
Cash used in operating activities	(11,666,217)	(12,078,825)
Cash flows from investing activities:
Refund of rental deposit	0	7,000
Purchases of marketable investment securities	(16,851,568)	(25,552,679)
Maturities of marketable investment securities	19,849,795	36,838,960
Cash provided by investing activities	2,998,227	11,293,281
Cash flows from financing activities:
Proceeds from debt	0	10,000,000
Debt repayments	(3,333,334)	0
Proceeds from stock option exercises	56,200	0
Proceeds from sale of Class A and Class B units	5,595,542	0
Proceeds from exercise of pre-funded warrants	155	0
Net proceeds from sale of common stock through ATM	8,000,411	652,334
Cash provided by financing activities	10,318,974	10,652,334
Net increase in cash and cash equivalents	1,650,984	9,866,790
Cash, cash equivalents and restricted cash at beginning of period	13,077,539	3,210,749
Cash, cash equivalents and restricted cash at end of period	14,728,523	13,077,539
Supplemental disclosure of cash flow information:
Interest paid	545,536	533,542
Income taxes paid	700	700
Supplemental disclosure of non-cash investing and financing activities:
Unrealized net gain on marketable investment securities	925	3,653
Accrued final payment charge on debt	221,209	259,865
Allocation of equity offering proceeds to warrant liability	$ 4,827,600	$ 0