UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 14, 2017

ANTHERA PHARMACEUTICALS, INC.

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (510) 856-5600

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Purchase Agreement

On June 19, 2017, Anthera Pharmaceuticals, Inc. (the “Company”) entered into a purchase agreement (the “Purchase Agreement”) with Lincoln Park Capital Fund, LLC (“LPC”), pursuant to which the Company has the right to sell to LPC up to $10,000,000 in shares of the Company’s common stock, par value $0.001 per share (“Common Stock”), subject to certain limitations and conditions set forth in the Purchase Agreement.

Pursuant to the Purchase Agreement, upon the satisfaction of all of the conditions to the Company’s right to commence sales under the Purchase Agreement (the “Commencement”), LPC is initially purchasing $500,000 in shares of Common Stock at $1.718 per share. Thereafter, on any business day and as often as every other business day over the 30-month term of the Purchase Agreement, and up to an aggregate amount of an additional $9,500,000 (subject to certain limitations) in shares of Common Stock, the Company has the right, from time to time, at its sole discretion and subject to certain conditions to direct LPC to purchase up to 75,000 shares of Common Stock, which amount can be increased under certain circumstances. The purchase price of shares of Common Stock pursuant to the Purchase Agreement will be based on prevailing market prices of Common Stock at the time of sales without any fixed discount, and the Company will control the timing and amount of any sales of Common Stock to LPC, but in no event will LPC be required to purchase more than $750,000 worth of shares on any single regular purchase date (excluding an accelerated purchase request on such date). In addition, the Company may direct LPC to purchase additional amounts as accelerated purchases under certain circumstances.

All shares of Common Stock to be issued and sold to LPC under the Purchase Agreement will be issued pursuant to the Company’s effective shelf registration statement on Form S-3 (Registration No. 333-210166), filed with the Securities and Exchange Commission in accordance with the provisions of the Securities Act of 1933, as amended, and declared effective on April 18, 2016, and the prospectus supplement thereto dated June 19, 2017.

The Purchase Agreement contains customary representations, warranties and agreements of the Company and LPC, limitations and conditions to completing future sale transactions, indemnification rights and other obligations of the parties. There is no upper limit on the price per share that LPC could be obligated to pay for Common Stock under the Purchase Agreement. The Company has the right to terminate the Purchase Agreement at any time, at no cost or penalty. Actual sales of shares of Common Stock to LPC under the Purchase Agreement will depend on a variety of factors to be determined by the Company from time to time, including (among others) market conditions, the trading price of the Common Stock and determinations by the Company as to available and appropriate sources of funding for the Company and its operations. As consideration for entering into the Purchase Agreement, the Company has agreed to issue to LPC 121,018 shares of Common Stock on the date of the initial purchase, and up to 60,690 additional shares of Common Stock on a pro rata basis as LPC purchases up to $10,000,000 worth of the Company’s shares (including the initial purchase of $500,000) in the Company’s discretion under the Purchase Agreement over the term of the agreement. The Company will not receive any cash proceeds from the issuance of these 121,018 shares or the 60,690 shares that may be issued if subsequent funding is received by the Company.

This Current Report on Form 8-K shall not constitute an offer to sell or a solicitation of an offer to buy any shares of Common Stock, nor shall there be any sale of shares of Common Stock in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or other jurisdiction.

The Purchase Agreement is filed as Exhibit 1.1, to this Current Report on Form 8-K and incorporated herein by reference. The foregoing descriptions of such agreement and the transactions contemplated thereby are qualified in their entirety by reference to such exhibits. In addition, the Purchase Agreement has been included to provide investors with information regarding its terms. The Purchase Agreement is not intended to provide any other factual information about the Company. The Purchase Agreement contains representations and warranties that the Company has made to LPC. The assertions embodied in those representations and warranties are qualified by information in confidential disclosure schedules that the Company has provided to LPC in connection with signing the Purchase Agreement. The disclosure schedules contain information that modifies, qualifies and creates exceptions to the representations and warranties set forth in the Purchase Agreement. Accordingly, investors should not rely on the representations and warranties as characterizations of the actual state of facts at the time they were made or otherwise.

Suspension of Sales under Sales Agreement

On June 19, 2017, prior to the filing of the above referenced prospectus supplement, the Company filed a prospectus supplement suspending and reducing all offerings pursuant to its existing sales agreement with H.C. Wainwright & Co., LLC to $0.

On June 14, 2017, Klara Dickinson-Eason tendered her letter of resignation from the role of Senior Vice President, Chief Regulatory Officer, effective June 20, 2017. Ms. Dickinson-Eason will continue to support the Company in a key advisory role with respect to the Company’s regulatory strategy. The Board of Directors of the Company and its management are thankful for Ms. Dickinson-Eason’s continued support and to provide oversight of the Company’s regulatory efforts.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.