v3.20.1
Statements of Cash Flows - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Cash flows from operating activities:    
Net loss $ (38,399,089) $ (50,840,122)
Adjustments to reconcile net loss to Net cash used in operating activities:    
Depreciation and amortization 781,228 1,054,720
Stock based compensation 10,646,580 16,753,754
Change in operating lease right-of-use assets 786,342  
Bad debt expense 35,000  
Loss on disposal of property and equipment 7,463  
Amortization of prepaid rent from stock issuance to landlord   80,784
Changes in operating assets and liabilities:    
Accounts receivable (53,594) (44,550)
Prepaid expenses and other current assets 130,809 445,270
Other assets   30,102
Accounts payable (189,866) (163,305)
Accrued expenses 284,748 156,324
Operating lease liabilities (662,766)  
Deferred revenue 12,000  
Net cash used in operating activities (26,621,145) (32,527,023)
Cash flows from investing activities:    
Purchases of property and equipment (196,199) (859,819)
Net cash used in investing activities (196,199) (859,819)
Cash flows from financing activities:    
Net proceeds from the sales of common stock 23,319,156 38,846,815
Net proceeds from an at-the-market ("ATM") offering 4,557,693  
Proceeds from the exercise of stock options 400,103 1,319,461
Proceeds from contributions to employee stock purchase plan 457,362 531,797
Net cash provided by financing activities 28,394,948 40,698,073
Net increase in cash and cash equivalents 1,577,604 7,311,231
Cash and cash equivalents - beginning 20,106,485 12,795,254
Cash and cash equivalents – ending 21,684,089 20,106,485
Restricted Stock Units (RSUs) [Member]    
Cash flows from financing activities:    
Shares repurchased for tax withholdings on vesting (10,207)  
Supplemental disclosure of non-cash financing activities:    
Common stock issued 11 10
Performance Shares [Member]    
Cash flows from financing activities:    
Shares repurchased for tax withholdings on vesting $ (329,159)  
Supplemental disclosure of non-cash financing activities:    
Common stock issued   $ 3

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