Stockholders’ Equity and Stock-Based Compensation (Tables)
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6 Months Ended |
Jun. 30, 2021 |
| Share-based Payment Arrangement [Abstract] |
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| Schedule of Warrant Activity |
A summary of the Company’s warrant activity during the six months ended June 30, 2021 was as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Shares of Stock under Warrants | | Weighted- Average Exercise Price | | Weighted- Average Remaining Contractual Term | | Aggregate Intrinsic Value | | Outstanding at January 1, 2021 | 15,174,000 | | | $ | 2.34 | | | 3.76 | | $ | 26,841,000 | | | Granted | — | | | | | | | | | Exercised | (10,789,000) | | | 0.88 | | | | | 58,175,000 | | | Canceled | (24,000) | | | | | | | | Outstanding at June 30, 2021 | 4,361,000 | | | $ | 5.95 | | | 2.27 | | $ | 6,904,000 | |
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| Summary of Stock Option Activity |
A summary of the Company’s stock option activity during the six months ended June 30, 2021 was as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Shares of Stock under Stock Options | | Weighted- Average Exercise Price | | Weighted- Average Remaining Contractual Term | | Aggregate Intrinsic Value | | Outstanding at January 1, 2021 | 5,290,000 | | | $ | 1.91 | | | 8.7 | | $ | 10,178,000 | | | Granted | 5,067,000 | | | 7.48 | | | | | | | Exercised | (162,000) | | | 2.55 | | | | | $ | 1,102,000 | | | Canceled | (645,000) | | | 2.64 | | | | | | Outstanding at June 30, 2021 | 9,550,000 | | | $ | 4.81 | | | 9.16 | | $ | 27,042,000 | | Vested and exercisable at June 30, 2021 | 1,896,000 | | | $ | 3.86 | | | 8.02 | | $ | 7,555,000 | |
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| Summary of Recognized Stock-Based Compensation Expense |
The Company recognized stock-based compensation expense for the periods presented as follows: | | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended June 30, | | Six Months Ended June 30, | | 2021 | | 2020 | | 2021 | | 2020 | | Research and development | $ | 384,000 | | | $ | 66,000 | | | $ | 465,000 | | | $ | 133,000 | | | General and administrative | 1,374,000 | | | 262,000 | | | 1,664,000 | | | 523,000 | | | Total stock-based compensation expense | $ | 1,758,000 | | | $ | 328,000 | | | $ | 2,129,000 | | | $ | 656,000 | |
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| Schedule of Weighted-Average Assumptions in Black -Scholes Option Pricing Model |
The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants during the periods presented were as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended June 30, | | Six Months Ended June 30, | | 2021 | | 2020 | | 2021 | | 2020 | | Risk-free interest rate | 1.1 | % | | 0.4 | % | | 1.1 | % | | 1.1 | % | | Expected volatility | 80.4 | % | | 77.9 | % | | 80.4 | % | | 72.2 | % | | Expected term (in years) | 6.0 | | 5.5 | | 6.0 | | 5.9 | | Expected dividend yield | 0.0 | % | | 0.0 | % | | 0.0 | % | | 0.0 | % |
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