18.	Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock

On December 16, 2016, the Company entered into a purchase agreement (the “Purchase Agreement”) with Lincoln Park Capital Fund, LLC, (“Lincoln Park”), pursuant to which the Company has the right to sell to Lincoln Park up to an aggregate of $25.0 million in shares of the Company’s common stock, (the “Common Stock”), subject to certain limitations and conditions set forth in the Purchase Agreement. From time to time on any trading day the Company selects, the Company has the right, in its sole discretion, subject to the conditions and limitations in the Purchase Agreement, to direct Lincoln Park to purchase up to 150,000 shares of Common Stock (each such purchase, a “Regular Purchase”) over the 36-month term of the Purchase Agreement. The purchase price of shares of Common Stock pursuant to the Purchase Agreement will be based on the prevailing market price at the time of sale as set forth in the Purchase Agreement. There are no trading volume requirements or restrictions under the Purchase Agreement. Lincoln Park’s obligation under each Regular Purchase shall not exceed $2.0 million. There is no upper limit on the price per share that Lincoln Park must pay for Common Stock under the Purchase Agreement, but in no event will shares be sold to Lincoln Park on a day the Company’s closing price is less than the floor price as set forth in the Purchase Agreement. Both the amount and frequency of the Regular Purchases can be increased upon the mutual agreement of the Company and Lincoln Park. The Company will control the timing and amount of any sales of shares of Common Stock to Lincoln Park. The Company may, in its sole discretion, direct Lincoln Park to purchase additional amounts as accelerated purchases if on the date of a Regular Purchase the closing sale price of the Common Stock is not below the threshold price as set forth in the Purchase Agreement. The Company and Lincoln Park may mutually agree to increase the amount of Common Stock sold to Lincoln Park on any accelerated purchase date. The Company issued to Lincoln Park 312,538 shares of Common Stock as commitment shares in consideration for the Purchase Agreement through December 31, 2016. The Company shall issue pro rata up to an additional 152,434 shares of Common Stock to Lincoln Park as determined by the number of shares Common Stock purchased by Lincoln Park pursuant to the Purchase Agreement. All sales of shares have been and will continue to be made pursuant to an effective shelf registration statement on Form S-3 filed with the SEC. Sales under the Purchase Agreement for the year ended December 31, 2016 were 300,000 shares, with gross proceeds of $412,500 and net proceeds of $392,500.

On February 20, 2015, the Company entered into a Controlled Equity Offering SM Sales Agreement (the “2015 Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”), as sales agent, pursuant to which the Company sold through Cantor, from time to time, up to $25.0 million in shares of common stock in an at-the-market offering. All sales of shares were made pursuant to an effective shelf registration statement on Form S-3 filed with the SEC. The Company pays Cantor a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the Sales Agreement. Sales under the 2015 Sales Agreement have been fully sold as of February 9, 2016, with cumulative shares of 7,724,488, gross proceeds of $25.0 million and net proceeds of $24.0 million.

On June 11, 2015, the Company sold 16,666,667 shares of common stock at a public offering price of $3.00 per share for aggregate gross proceeds of $50.0 million in an underwritten firm commitment public offering. Net proceeds after issuance costs were $46.4 million. The closing of the public offering occurred on June 17, 2015. The Company granted the underwriters an option, exercisable for 30 days, to purchase up to an additional 2,500,000 shares of Common Stock.

On July 10, 2015, the underwriters exercised a portion of their option to acquire an additional 2,075,000 shares at the public offering price of $3.00 per share for aggregate additional gross proceeds of $6.2 million. Net proceeds after issuance costs were $5.8 million. The purchase of the option shares closed on July 15, 2015. Total proceeds (including the option) were $52.2 million, net of issuance costs of $4.0 million. The common stock was offered and sold pursuant to the Shelf Registration Statement filed in November 2014 (the “November 2014 Shelf Registration Statement”), which was declared effective on December 19, 2014. The November 2014 Shelf Registration Statement allowed the Company to raise up to $100.0 million through the sale of debt securities, common stock, preferred stock, warrants, or any combination thereof. On March 3, 2016, the Company filed an amendment to the November 2014 Shelf Registration Statement increasing the amount available from $100.0 million to $150.0 million.

On February 9, 2016, the Company entered into a Controlled Equity Offering SM Sales Agreement (the “2016 Sales Agreement”) with Cantor, as sales agent, pursuant to which the Company can sell through Cantor, from time to time, up to $43.6 million in shares of common stock in an at-the-market offering. All sales of shares have been and will continue to be made pursuant to an effective shelf registration statement on Form S-3 filed with the SEC. The Company pays Cantor a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2016 Sales Agreement. Unless otherwise terminated earlier, the 2016 Sales Agreement continues until all shares available under the Sales Agreement have been sold.

The following table summarizes the total sales under the 2015 Sales Agreement and 2016 Sales Agreement for the periods indicated (in thousands, except per share amounts):

	2016 Sales Agreement		2015 Sales Agreement
	Year Ended December 31, 2016		Year Ended December 31, 2016		Year Ended December 31, 2015
Total shares of common stock sold		8,763.4		5,710.2		2,014.3
Average price per share	$	4.70	$	3.23	$	3.25
Gross proceeds	$	41,156	$	18,454	$	6,546
Commissions earned by Cantor	$	1,235	$	553	$	197
Other issuance costs	$	185	$	—	$	259

On April 14, 2014, the Company sold 12,500,000 shares of common stock at a public offering price of $4.00 per share for aggregate gross proceeds of $50.0 million in an underwritten firm commitment public offering. Certain of the Company’s existing stockholders that are affiliated with certain of the Company’s directors purchased $10.0 million of common stock in the public offering. The closing of the public offering occurred on April 21, 2014. The Company granted the underwriters an option, exercisable for 30 days, to purchase up to an additional 1,875,000 shares of Common Stock to cover over-allotments. On April 30, 2014, the underwriters exercised a portion of their over-allotment option to acquire an additional 1,610,000 shares at the public offering price of $4.00 per share for aggregate additional gross proceeds of $6.4 million. The purchase of the over-allotment shares closed on May 5, 2014. Total proceeds were $52.4 million, net of issuance costs of $4.0 million. The common stock was offered and sold pursuant to the Shelf Registration Statement filed in January 2014 (the “January 2014 Shelf Registration Statement”), which was declared effective on April 2, 2014. The January 2014 Shelf Registration Statement allowed the Company to raise up to $100.0 million through the sale of debt securities, common stock, preferred stock, warrants, or any combination thereof. As of December 31, 2016, the Company had $37.8 million available for future financings under such shelf registration statements. In addition, approximately $2.4 million is reserved for future issuances under the 2016 ATM Offering and $24.6 million is reserved for future issuances under the Lincoln Park Agreement.