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

March 19, 2015

(Date of Report - date of earliest event reported)

Tekmira Pharmaceuticals Corporation

(Exact Name of Registrant as Specified in Its Charter)

(604) 419-3200

(Registrant’s Telephone Number, Including Area Code)

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:

On March 19, 2015, Tekmira Pharmaceuticals Corporation (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Leerink Partners LLC and RBC Capital Markets, LLC, as representatives of the several underwriters named therein (collectively, the “Underwriters”), relating to an underwritten public offering of 7,500,000 common shares of the Company (the “Underwritten Shares”). All of the Underwritten Shares are being sold by the Company. The offering price of the Underwritten Shares to the public is $20.25 per common share, and the Underwriters have agreed to purchase the Underwritten Shares from the Company pursuant to the Underwriting Agreement at a price of $19.035 per common share. After underwriting discounts and commissions and estimated offering expenses, the Company expects to receive net proceeds from the offering of approximately $142.4 million. Under the terms of the Underwriting Agreement, the Company has granted the Underwriters an option, exercisable for 30 days, to purchase up to an additional 1,125,000 common shares (the “Option Shares” and together with the Underwritten Shares, the “Shares”) at the public offering price less the underwriting discounts and commissions.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions.

The Underwritten Shares and any Option Shares will be issued pursuant to a registration statement on Form S-3 (File No. 333-200625). A prospectus supplement relating to the offering has been filed with the Securities and Exchange Commission. The closing of the offering is expected to take place on March 25, 2015, subject to customary closing conditions.

A copy of the Underwriting Agreement is attached as Exhibit 1.1 hereto and is incorporated herein by reference. The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to such exhibit.

A copy of the legal opinion and consent of Farris, Vaughan, Wills & Murphy LLP, Canadian counsel to the Company, relating to the Company’s common shares is attached as Exhibit 5.1 hereto.

The Company issued a press release on March 19, 2015 announcing the pricing of the underwritten public offering. The press release is attached as Exhibit 99.1, and the information contained therein is incorporated herein by reference.

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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.

Date: March 19, 2015

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