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): October 1, 2018

AKEBIA THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (617) 871-2098

n/a

(Former name or former address, if changed since last report)

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 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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.  ☒

Item 1.01 Entry into a Material Definitive Agreement.

On October 1, 2018, Akebia Therapeutics, Inc., a Delaware corporation (“Akebia”) entered into the First Amendment to Agreement and Plan of Merger (the “First Amendment”) with Alpha Therapeutics Merger Sub, Inc., a Delaware corporation and a direct, wholly owned subsidiary of Akebia (“Merger Sub”), and Keryx Biopharmaceuticals, Inc., a Delaware corporation (“Keryx”), amending the Agreement and Plan of Merger dated June 28, 2018, by and among Akebia, Merger Sub, and Keryx (the “Merger Agreement”). As was previously disclosed, pursuant to the Merger Agreement, and subject to the satisfaction or waiver of the conditions specified therein, Merger Sub shall be merged with and into Keryx, with Keryx surviving as a wholly owned subsidiary of Akebia (the “Merger”).

The First Amendment provides that, as of the effective time of the Merger (the “Effective Time”), Akebia must take all necessary corporate action to cause an increase in the size of the Akebia Board of Directors (the “Akebia Board”) to ten (10) directors, comprising (i) four (4) directors designated by the Akebia Board, each of whom shall be a director of Akebia prior to the Effective Time and be reasonably acceptable to Keryx (the “Continuing Directors”), (ii) five (5) directors designated by the Keryx Board of Directors (the “Keryx Board”), each of whom shall be a director of Keryx prior to the Effective Time and be reasonably acceptable to Akebia (the “Keryx Board Designees”), and (iii) one (1) additional independent director to be designated by the Akebia Board and the Keryx Board (the “Additional Director”), who is neither a member of the Akebia Board nor a member of the Keryx Board prior to the Effective Time. The Additional Director shall serve as chairperson of the Akebia Board as of the Effective Time. Pursuant to the First Amendment, Akebia and Keryx shall designate the Continuing Directors, the Keryx Board Designees and the Additional Director, as applicable, as soon as practicable, but no later than immediately prior to the Effective Time. The First Amendment also provides that, as of the Effective Time, the Continuing Directors, the Keryx Board Designees, and the Additional Director shall be allocated among the three classes of directors as follows:

Other than as expressly modified pursuant to the First Amendment, the Merger Agreement remains in full force and effect as originally executed on June 28, 2018. The foregoing summary does not purport to be a complete description and is qualified in its entirety by reference to the full text of the First Amendment, which is attached hereto as Exhibit 2.1 and incorporated herein by reference.

Additional Information and Where to Find It

In connection with the proposed merger, Akebia Therapeutics and Keryx Biopharmaceuticals plan to file with the SEC and mail or otherwise provide to their respective shareholders a joint proxy statement/prospectus regarding the proposed transaction. BEFORE MAKING ANY VOTING DECISION, AKEBIA’S AND KERYX’S RESPECTIVE SHAREHOLDERS ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS IN ITS ENTIRETY WHEN IT BECOMES AVAILABLE AND ANY OTHER DOCUMENTS FILED BY EACH OF AKEBIA AND KERYX WITH THE SEC IN CONNECTION WITH THE PROPOSED MERGER OR INCORPORATED BY REFERENCE THEREIN BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION AND THE PARTIES TO THE PROPOSED TRANSACTION. Investors and shareholders will be able to obtain a free copy of the joint proxy statement/prospectus and other documents containing important information about Akebia and Keryx, once such documents are filed with the SEC, through the website maintained by the SEC at www.sec.gov. Akebia and Keryx make available free of charge at www.akebia.com and www.keryx.com, respectively (in the “Investors” section), copies of materials they file with, or furnish to, the SEC.

Participants in the Solicitation

This document does not constitute a solicitation of proxy, an offer to purchase or a solicitation of an offer to sell any securities. Akebia Therapeutics, Keryx Biopharmaceuticals and their respective directors, executive officers and

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certain employees and other persons may be deemed to be participants in the solicitation of proxies from the shareholders of Akebia and Keryx in connection with the proposed merger. Security holders may obtain information regarding the names, affiliations and interests of Akebia’s directors and officers in Akebia’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017, which was filed with the SEC on March 12, 2018 and its definitive proxy statement for the 2018 annual meeting of shareholders, which was filed with the SEC on April 30, 2018. Security holders may obtain information regarding the names, affiliations and interests of Keryx’s directors and officers in Keryx’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017, which was filed with the SEC on February 21, 2018, and the Amendment No. 1 on Form 10-K/A, which was filed with the SEC on April 30, 2018, and its definitive proxy statement for the 2018 annual meeting of shareholders, which was filed with the SEC on May 31, 2018. To the extent the holdings of Akebia’s securities by Akebia’s directors and executive officers or the holdings of Keryx securities by Keryx’s directors and executive officers have changed since the amounts set forth in Akebia’s or Keryx’s respective proxy statement for its 2018 annual meeting of shareholders, such changes have been or will be reflected on Statements of Change in Ownership on Form 4 filed with the SEC. Additional information regarding the interests of such individuals in the proposed merger will be included in the joint proxy statement/prospectus relating to the proposed merger when it is filed with the SEC. These documents (when available) may be obtained free of charge from the SEC’s website at www.sec.gov, Akebia’s website at www.akebia.com and Keryx’s website at www.keryx.com.

Forward-Looking Statements

These materials contain forward-looking statements within the meaning of the federal securities law. Such statements are based upon current plans, estimates and expectations that are subject to various risks and uncertainties. The inclusion of forward-looking statements should not be regarded as a representation that such plans, estimates and expectations will be achieved. Words such as “anticipate,” “create,” “expect,” “project,” “intend,” “believe,” “may,” “will,” “should,” “plan,” “could,” “target,” “contemplate,” “estimate,” “position,” “predict,” “potential,” “opportunity” and words and terms of similar substance used in connection with any discussion of future plans, actions or events identify forward-looking statements. All statements, other than historical facts, including statements regarding the ability of the parties to complete the merger considering the various closing conditions; the consummation of the Merger; the composition of the board of directors of the combined entity following consummation of the Merger; and the assigned classes of the members of the board of directors of the combined entity following consummation of the Merger are forward-looking statements. Important factors that could cause actual results to differ materially from Akebia’s and Keryx’s plans, estimates or expectations could include, but are not limited to: (i) Akebia or Keryx may be unable to obtain stockholder approval as required for the merger; (ii) conditions to the closing of the merger may not be satisfied; (iii) the merger may involve unexpected costs, liabilities or delays; (iv) the effect of the announcement of the merger on the ability of Akebia or Keryx to retain and hire key personnel and maintain relationships with customers, suppliers and others with whom Akebia or Keryx does business, or on Akebia’s or Keryx’s operating results and business generally; (v) Akebia’s or Keryx’s respective businesses may suffer as a result of uncertainty surrounding the merger and disruption of management’s attention due to the merger; (vi) the outcome of any legal proceedings related to the merger; (vii) Akebia or Keryx may be adversely affected by other economic, business, and/or competitive factors; (viii) the occurrence of any event, change or other circumstances that could give rise to the termination of the merger agreement; (ix) risks that the merger disrupts current plans and operations and the potential difficulties in employee retention as a result of the merger; (x) the risk that Akebia or Keryx may be unable to obtain governmental and regulatory approvals required for the transaction, or that required governmental and regulatory approvals may delay the transaction or result in the imposition of conditions that could reduce the anticipated benefits from the proposed transaction or cause the parties to abandon the proposed transaction; (xi) risks that the anticipated benefits of the merger or other commercial opportunities may otherwise not be fully realized or may take longer to realize than expected; (xii) the impact of legislative, regulatory, competitive and technological

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changes; (xiii) expectations for future clinical trials, the timing and potential outcomes of clinical studies and interactions with regulatory authorities; and (xiv) other risks to the consummation of the merger, including the risk that the merger will not be consummated within the expected time period or at all. Additional factors that may affect the future results of Akebia and Keryx are set forth in their respective filings with the SEC, including each of Akebia’s and Keryx’s most recently filed Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other filings with the SEC, which are available on the SEC’s website at www.sec.gov. See in particular Item 1A of Akebia’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2018 under the heading “Risk Factors” and Item 1A of Keryx’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2018 under the heading “Risk Factors.” The risks and uncertainties described above and in Akebia’s most recent Quarterly Report on Form 10-Q and Keryx’s most recent Quarterly Report on Form 10-Q are not exclusive and further information concerning Akebia and Keryx and their respective businesses, including factors that potentially could materially affect their respective businesses, financial condition or operating results, may emerge from time to time. Readers are urged to consider these factors carefully in evaluating these forward-looking statements, and not to place undue reliance on any forward-looking statements. Readers should also carefully review the risk factors described in other documents that Akebia and Keryx file from time to time with the SEC. The forward-looking statements in these materials speak only as of the date of these materials. Except as required by law, Akebia and Keryx assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future.

Item 9.01 Financial Statements and Exhibits.

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SIGNATURE

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.

Date: October 1, 2018

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Exhibit 2.1

FIRST AMENDMENT TO AGREEMENT AND PLAN OF MERGER

This FIRST AMENDMENT TO AGREEMENT AND PLAN OF MERGER (this “Amendment”), dated as of October 1, 2018 is entered into by and among Akebia Therapeutics, Inc., a Delaware corporation (“Akebia”); Alpha Therapeutics Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Akebia (“Merger Sub”); and Keryx Biopharmaceuticals, Inc., a Delaware corporation (“Keryx” and collectively with Akebia and Merger Sub, the “Parties,” and each a “Party”). Capitalized terms used herein and not otherwise defined shall have the same meanings as set forth in the Agreement and Plan of Merger, dated as of June 28, 2018, by and among the Parties (the “Merger Agreement”).

WHEREAS, the Parties have agreed to amend a provision of the Merger Agreement as described herein; and

WHEREAS, the Boards of Directors of Keryx and Akebia each have approved this Amendment.

NOW, THEREFORE, in consideration of the mutual covenants and agreements contained in the Merger Agreement and for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Parties agree as follows:

1.    New Section 1.13(a). Section 1.13(a) of the Merger Agreement titled “Post-Merger Operations” shall be amended and restated in its entirety and shall read as follows:

“(a)     Unless otherwise agreed to in writing by the Parties, Akebia shall take all necessary corporate action to cause, as of the Effective Time, an increase in the size of the Akebia Board to ten (10) directors, comprising (i) four (4) directors designated by the Akebia Board, each of whom shall be a director of Akebia prior to the Effective Time and be reasonably acceptable to Keryx (the “Continuing Directors”), (ii) five (5) directors designated by the Keryx Board, each of whom shall be a director of Keryx prior to the Effective Time and be reasonably acceptable to Akebia (the “Keryx Board Designees”), and (iii) one (1) additional independent director to be designated by the Akebia Board and the Keryx Board (the “Additional Director”), who is neither a member of the Akebia Board nor a member of the Keryx Board prior to the Effective Time. The Additional Director shall serve as chairperson of the Akebia Board as of the Effective Time. Each Continuing Director, Keryx Board Designee and Additional Director shall serve until such individual’s successor is duly elected or appointed and qualified in accordance with applicable Law. Akebia and Keryx shall designate the Continuing Directors, the Keryx Board Designees and the Additional Director, as applicable, as soon as practicable, but no later than immediately prior to the Effective Time. As of the Effective Time, the Continuing Directors, the Keryx Board Designees and the Additional Director shall be allocated among the three classes of directors as follows:

If, prior to the Effective Time, any designated Continuing Director, Keryx Board Designee or Additional Director becomes unable or unwilling to serve on the Akebia Board as of the Effective Time, a replacement for such designee shall be determined prior to the Effective Time in accordance with the principles set forth in this Section 1.13(a).

2.    Full Force and Effect. Except as expressly amended hereby, each term, provision, Exhibit and Schedule of the Merger Agreement will and does remain in full force and effect.

3.    References. Each reference in the Merger Agreement to “this Agreement,” “hereof,” “herein” and “hereunder” and words of similar import referring to the Merger Agreement shall mean and be a reference to the Merger Agreement as amended by this Amendment. Notwithstanding anything to the contrary herein, all references in the Merger Agreement, the Keryx Disclosure Letter, the Akebia Disclosure Letter and the Annexes to “the date hereof” or “the date of this Agreement” shall refer to June 28, 2018.

4.    Headings. The headings contained in this Amendment are for reference purposes only and shall not affect in any way the meaning or interpretation of this Amendment.

5.    Miscellaneous. The provisions of Sections 8.02 (Amendment), Sections 8.05 (Entire Agreement; Counterparts), 8.06 (Applicable Law; Jurisdiction), 8.07 (Waiver of Jury Trial), 8.08 (Assignability) and 8.13 (Severability) of the Merger Agreement shall apply to this Amendment mutatis mutandis.

[Signature Page Follows]

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IN WITNESS WHEREOF, the Parties have caused this Amendment to be duly executed and delivered as of the date first written above by their respective officers thereunto duly authorized.

[Signature Page to First Amendment to Agreement and Plan of Merger]