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): January 14, 2015

REGADO BIOSCIENCES, INC.

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code (908) 580-2100

(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 (see General Instruction A.2. below):

Item 8.01 Other Events.

On January 14, 2015, Regado Biosciences, Inc., a Delaware corporation (the “Company”) entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”) with Tobira Therapeutics, Inc., a Delaware corporation (“Tobira”), a clinical-stage biopharmaceutical company focused on the development and commercialization of innovative therapeutics to treat liver disease, human immunodeficiency virus, fibrosis and inflammation, Landmark Merger Sub Inc., a Delaware corporation and wholly-owned subsidiary of the Company (the “Merger Sub”) and, solely with respect to Section 5.14 of the Merger Agreement, Brent Ahrens, as the agent of Tobira’s stockholders, pursuant to which the Merger Sub will be merged with and into Tobira (the “Merger”), with Tobira surviving the Merger as a wholly-owned subsidiary of the Company. A copy of the press release issued by the Company titled “Regado Biosciences and Tobira Therapeutics Announce Merger Agreement to Create Leading NASH Company” is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference. The terms of the Merger Agreement, including the conditions thereto, will be described in a subsequent filing on Form 8-K.

Additional Information and Where to Find It

In connection with the Merger, the Company plans to file with the SEC a proxy statement of the Company, as well as other relevant documents concerning the proposed transaction. STOCKHOLDERS ARE URGED TO READ THE PROXY STATEMENT REGARDING THE MERGER WHEN IT BECOMES AVAILABLE AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THOSE DOCUMENTS, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. A free copy of the proxy statement and other filings containing information about the Company and Tobira may be obtained at the SEC’s Internet site (http://www.sec.gov). You will also be able to obtain these documents, free of charge, from the Company at www.regadobiosciences.com under the heading “Investors / SEC Filings.”

The Company and Tobira and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the Company’s and Tobira’s stockholders in connection with the Merger. Additional information regarding the interests of those participants and other persons who may be deemed participants in the Merger may be obtained by reading the proxy statement regarding the Merger when it becomes available. Free copies of this document may be obtained as described in the preceding paragraph. This Form 8-K shall not constitute an offer to sell or the solicitation of an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

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: January 14, 2015

REGADO BIOSCIENCES, INC.

EXHIBIT INDEX