Sales of Equity Securities	6 Months Ended
Jun. 30, 2021
Equity [Abstract]
Sales of Equity Securities	3. Sales of Equity Securities In January 2020, the Company issued an aggregate of 692,725 shares of its common stock pursuant to the exercise of certain warrants issued by the Company in February 2019 and March 2019, as part of a warrant repricing and exchange transaction. As part of the warrant repricing and exchange transaction, the Company issued an aggregate of 692,725 new warrants in exchange for the exercise of the February 2019 and March 2019 warrants and received net proceeds of approximately $2.3 million. As a result of the warrant repricing, the exercise price of warrants to purchase an aggregate of 89,657 shares of common stock issued by the Company in January 2018 was adjusted from $4.05 to $3.495 per share. In January 2020, the Company issued 192,750 shares of common stock pursuant to the partial exercise of the underwriters’ overallotment option from the Company’s December 2019 public offering. The net proceeds to the Company from the overallotment closing, was approximately $700,000. The warrants issued in connection with the warrant repricing and exchange transaction were considered inducement warrants and are classified in equity. In addition, the modification expense associated with the change in fair value due to the repricing of February and March 2019 warrants is recorded as inducement expense, which was approximately $191,000. The fair value of the warrants issued was approximately $1.9 million. The fair value of the inducement warrants and warrant modification of $2.1 million was expensed as warrant inducement expense in the accompanying condensed statements of operations for the six months ended June 30, 2020. On March 2, 2020, the Company sold and issued 2,300,000 shares of its common stock at a negotiated purchase price of $4.00 per share in a registered direct offering and received net cash proceeds of approximately $8.6 million after deducting placement agent fees and other expenses. On March 4, 2020, the Company sold and issued 1,600,000 shares of its common stock at a negotiated purchase price of $4.10 per share in a registered direct offering and received net cash proceeds of approximately $6.1 million after deducting placement agent fees and other expenses. On April 16, 2020, the Company sold and issued 2,230,000 shares of its common stock at a negotiated purchase price of $4.60 per share in a registered direct offering and received net cash proceeds of approximately $9.6 million after deducting placement agent fees and other expenses. On May 12, 2021, the Company entered into a Controlled Equity Offering^SM Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (the “Sales Agent”), under which the Company may issue and sell from time to time up to $25,000,000 of its common stock through or to the Sales Agent, as sales agent or principal. The issuance and sale of these shares under the Sales Agreement, if any, is subject to the continued effectiveness of the Company’s shelf registration statement on Form S-3, filed with the Securities and Exchange Commission on April 24, 2020. Sales of the Company’s common stock, under the Sales Agreement are made at market prices by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. Each time the Company wishes to issue and sell common stock under the Sales Agreement, it notifies the Sales Agent of the number of shares to be issued, the dates on which such sales are anticipated to be made and any minimum price below which sales may not be made. Once the Company has so instructed the Sales Agent, unless the Sales Agent declines to accept the terms of the notice, the Sales Agent has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of the Sales Agent under the Sales Agreement to sell the Company’s common stock are subject to a number of conditions that the Company must meet. The offering of common stock pursuant to the Sales Agreement will terminate upon the earlier of (1) the sale of all common stock subject to the Sales Agreement and (2) termination of the Sales Agreement as permitted therein. The Sales Agreement may be terminated by the Company at any time upon ten days’ notice. The Sales Agent may terminate the Sales Agreement at any time upon ten days’ prior notice. The Sales Agent is entitled to compensation from the Company at a fixed commission rate equal to 3.0% of the gross sales price per share of any common stock sold under the Sales Agreement. During the three months ended June 30, 2021, the Company sold and issued 908,044 shares of its common stock at a weighted average purchase price of $4.67 under the Sales Agreement and received net cash proceeds of approximately $3.9 million after deducting sales agent commissions and other offering costs.

Sales of Equity Securities

6 Months Ended

Jun. 30, 2021

3. Sales of Equity Securities

In January 2020, the Company issued an aggregate of 692,725 shares of its common stock pursuant to the exercise of certain warrants issued by the Company in February 2019 and March 2019, as part of a warrant repricing and exchange transaction. As part of the warrant repricing and exchange transaction, the Company issued an aggregate of 692,725 new warrants in exchange for the exercise of the February 2019 and March 2019 warrants and received net proceeds of approximately $2.3 million. As a result of the warrant repricing, the exercise price of warrants to purchase an aggregate of 89,657 shares of common stock issued by the Company in January 2018 was adjusted from $4.05 to $3.495 per share. In January 2020, the Company issued 192,750 shares of common stock pursuant to the partial exercise of the underwriters’ overallotment option from the Company’s December 2019 public offering. The net proceeds to the Company from the overallotment closing, was approximately $700,000. The warrants issued in connection with the warrant repricing and exchange transaction were considered inducement warrants and are classified in equity. In addition, the modification expense associated with the change in fair value due to the repricing of February and March 2019 warrants is recorded as inducement expense, which was approximately $191,000. The fair value of the warrants issued was approximately $1.9 million. The fair value of the inducement warrants and warrant modification of $2.1 million was expensed as warrant inducement expense in the accompanying condensed statements of operations for the six months ended June 30, 2020.

On March 2, 2020, the Company sold and issued 2,300,000 shares of its common stock at a negotiated purchase price of $4.00 per share in a registered direct offering and received net cash proceeds of approximately $8.6 million after deducting placement agent fees and other expenses.

On March 4, 2020, the Company sold and issued 1,600,000 shares of its common stock at a negotiated purchase price of $4.10 per share in a registered direct offering and received net cash proceeds of approximately $6.1 million after deducting placement agent fees and other expenses.

On April 16, 2020, the Company sold and issued 2,230,000 shares of its common stock at a negotiated purchase price of $4.60 per share in a registered direct offering and received net cash proceeds of approximately $9.6 million after deducting placement agent fees and other expenses.

On May 12, 2021, the Company entered into a Controlled Equity Offering^SM Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (the “Sales Agent”), under which the Company may issue and sell from time to time up to $25,000,000 of its common stock through or to the Sales Agent, as sales agent or principal. The issuance and sale of these shares under the Sales Agreement, if any, is subject to the continued effectiveness of the Company’s shelf registration statement on Form S-3, filed with the Securities and Exchange Commission on April 24, 2020. Sales of the Company’s common stock, under the Sales Agreement are made at market prices by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. Each time the Company wishes to issue and sell common stock under the Sales Agreement, it notifies the Sales Agent of the number of shares to be issued, the dates on which such sales are anticipated to be made and any minimum price below which sales may not be made. Once the Company has so instructed the Sales Agent, unless the Sales Agent declines to accept the terms of the notice, the Sales Agent has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of the Sales Agent under the Sales Agreement to sell the Company’s common stock are subject to a number of conditions that the Company must meet. The offering of common stock pursuant to the Sales Agreement will terminate upon the earlier of (1) the sale of all common stock subject to the Sales Agreement and (2) termination of the Sales Agreement as permitted therein. The Sales Agreement may be terminated by the Company at any time upon ten days’ notice. The Sales Agent may terminate the Sales Agreement at any time upon ten days’ prior notice. The Sales Agent is entitled to compensation from the Company at a fixed commission rate equal to 3.0% of the gross sales price per share of any common stock sold under the Sales Agreement. During the three months ended June 30, 2021, the Company sold and issued 908,044 shares of its common stock at a weighted average purchase price of $4.67 under the Sales Agreement and received net cash proceeds of approximately $3.9 million after deducting sales agent commissions and other offering costs.