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): March 3, 2016

AVALANCHE BIOTECHNOLOGIES, INC.

(Exact Name of Registrant as Specified in its Charter)

1035 O’Brien Drive, Suite A

Menlo Park, CA 94025

(Address of principal executive offices, including Zip Code)

Registrant’s telephone number, including area code: (650) 272-6269

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:

Item 2.02 Results of Operations and Financial Conditions

On March 3, 2016, Avalanche Biotechnologies, Inc. issued a press release regarding, among other matters, its financial results for its fourth quarter and year ended December 31, 2015. A copy of the press release is furnished as Exhibit 99.1 to this Form 8-K.

This information in Item 2.02 of this Form 8-K and the Exhibit 99.1 attached hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that Section, or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Additional Information and Where to Find It

This Current Report on Form 8-K does not constitute a solicitation of any vote or approval. In connection with its previously announced proposed acquisition of Annapurna Therapeutics SAS, Avalanche Biotechnologies, Inc. (the “Company”) intends to file with the Securities and Exchange Commission (the “SEC”) a proxy statement of the Company, as well as other relevant documents concerning the proposed transaction. INVESTORS AND SECURITYHOLDERS OF THE COMPANY ARE URGED TO READ THE PROXY STATEMENT REGARDING THE PROPOSED TRANSACTION 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 may be obtained at the SEC website at www.sec.gov. You will also be able to obtain these documents, free of charge, from the Company by directing a written request to: Avalanche Biotechnologies, Inc., 1035 O’Brien Drive, Suite A, Menlo Park, CA 94025, Attention: Investor Relations. Investors and securityholders are urged to read the proxy statement and the other relevant materials when they become available before making any voting decision with respect to the issuance of the Company’s common stock or any other matters relating to the proposed transaction.

Certain Information Regarding Participants

The Company and its directors and executive officers may be deemed to be participants in the solicitation of proxies from the stockholders of the Company in connection with the proposed transaction and the issuance of the Company’s common stock. Information regarding the special interests of these directors and executive officers in the proposed transaction will be included in the proxy statement referred to above. Additional information regarding the directors and executive officers of the Company is also included in Avalanche’s Annual Report on Form 10-K for the year ended December 31, 2014 and the proxy statement for the Company’s 2015 Annual Meeting of Stockholders. These documents are available free of charge at the SEC web site at www.sec.gov and from Investor Relations at the Company at the address set forth above.

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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.

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EXHIBIT INDEX

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