CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 43,903,949	$ 61,746,748
Prepaid expenses and deposits	1,526,442	141,717
Interest receivable	56,189	108,177
Total current assets	45,486,580	61,996,642
Non-current assets:
Property, plant and equipment, net	417,528	147,668
Right-of-use assets, net	455,174
Total non-current assets	872,702	147,668
Total assets	46,359,282	62,144,310
Current liabilities:
Accounts payable and accrued liabilities	1,757,680	2,754,572
Lease liability	204,132
Warrant liability	31,000	49,000
Total current liabilities	1,992,812	2,803,572
Non-current liabilities:
Lease liability, net of current portion	280,247
Total non-current liabilities	280,247
Total liabilities	2,273,059	2,803,572
Commitments and contingencies (see Note 15)
Stockholders' equity:
Preferred stock - $0.001 par value, 5 million shares authorized and 0 shares issued and outstanding at December 31, 2019 and 2018, respectively
Common stock, $0.001 par value, 150 million shares authorized, 45.7 million and 45.4 million shares issued and outstanding as of December 31, 2019 and 2018, respectively	45,728	45,440
Additional paid-in capital	371,573,909	365,400,748
Accumulated deficit	(327,533,414)	(306,105,450)
Total stockholders' equity	44,086,223	59,340,738
Total liabilities and stockholders' equity	$ 46,359,282	$ 62,144,310

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.