Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 10,967,713	$ 19,217,382
Restricted cash		5,000,000
Marketable investment securities	35,672,059	449,992
Accrued interest income	232,568	391
Prepaid and other current assets	283,180	661,258
Total current assets	47,155,520	25,329,023
Other assets	23,753	23,753
Total assets	47,179,273	25,352,776
Current liabilities:
Accounts payable	906,476	1,597,220
Accrued expenses	1,444,188	1,653,178
Debt - current portion	3,957,627	3,333,333
Litigation settlement liability - current portion	2,500,000
Total current liabilities	8,808,291	6,583,731
Debt - non-current portion		2,257,075
Warrant liability	1,125,429	1,170,051
Litigation settlement liability - non-current portion	1,500,000
Total liabilities	11,433,720	10,010,857
Commitments and contingencies (notes 5, 7, 8 and 10)
Stockholders’ equity:
Preferred stock, par value $0.0001 per share, 10,000,000 shares authorized; zero issued and outstanding
Common stock, par value $0.0001 per share, 100,000,000 shares authorized; 88,296,360 and 70,041,967 issued and 88,290,650 and 70,036,257 outstanding	8,830	7,005
Additional paid-in capital	217,986,752	187,407,634
Treasury stock at cost, 5,710 shares	(40,712)	(40,712)
Accumulated other comprehensive loss	(186)
Accumulated deficit	(182,209,131)	(172,032,008)
Total stockholders’ equity	35,745,553	15,341,919
Total liabilities and stockholders’ equity	$ 47,179,273	$ 25,352,776

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).