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 13, 2017

ONCOGENEX PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (425) 686-1500

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 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.  ☐

Attached hereto as Exhibit 99.1 is a press release issued by OncoGenex Pharmaceuticals, Inc. (“OncoGenex”) on June 13, 2017 announcing that the special meeting of OncoGenex stockholders to vote on the proposed merger with Achieve Life Science, Inc. (“Achieve”) and related matters will be held on August 1, 2017, at 9:00 a.m. Pacific Time, at 1191 Second Avenue, Floor 10, Seattle, Washington, 98101. OncoGenex stockholders of record as of the close of business on June 13, 2017 are entitled to vote at the special meeting and will receive the final proxy statement/prospectus/information statement, which will be mailed to stockholders beginning June 19, 2017.

Reference is made to the Exhibit Index included with this Current Report on Form 8-K.

Additional Information about the Proposed Merger

This communication is being made in respect of the proposed merger involving OncoGenex Pharmaceuticals, Inc. and Achieve Life Science, Inc. OncoGenex filed a registration statement on Form S-4 (File No. 333-216961) with the SEC, which contains a proxy statement/prospectus/information statement, and plans to file with the SEC other documents regarding the proposed transaction. The registration statement was declared effective on June 13, 2017. The final proxy statement/prospectus/information statement will be sent to the stockholders of OncoGenex and Achieve. The final proxy statement/prospectus/information statement contains information about OncoGenex, Achieve, the proposed merger and related matters. STOCKHOLDERS ARE URGED TO READ THE FINAL PROXY STATEMENT/PROSPECTUS/INFORMATION STATEMENT (INCLUDING ANY AMENDMENTS OR SUPPLEMENTS) AND OTHER DOCUMENTS FILED WITH THE SEC CAREFULLY IN THEIR ENTIRETY, AS THEY CONTAIN IMPORTANT INFORMATION THAT STOCKHOLDERS SHOULD CONSIDER BEFORE MAKING A DECISION ABOUT THE MERGER AND RELATED MATTERS. In addition to receiving the final proxy statement/prospectus/information statement and proxy card by mail, stockholders will also be able to obtain the final proxy statement/prospectus/information statement, as well as other filings containing information about OncoGenex, without charge, from the SEC’s website (http://www.sec.gov) or, without charge, by directing a written request to: OncoGenex Pharmaceuticals, Inc., 19820 North Creek Parkway, Suite 201, Bothell, WA 98011, Attention: Investor Relations or to Achieve Life Science, Inc., 30 Sunnyside Avenue, Mill Valley, CA 94941, Attention: Rick Stewart.

This communication 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 offering of securities in connection with the proposed merger shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

Participants in Solicitation

OncoGenex and its executive officers and directors may be deemed to be participants in the solicitation of proxies from OncoGenex’s stockholders with respect to the matters relating to the proposed merger. Achieve and its officers and directors may also be deemed a participant in such solicitation. Information regarding interests that OncoGenex, Achieve and the executive officers or directors of OncoGenex or Achieve have in the proposed merger is set forth in the final proxy statement/prospectus/information

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statement that OncoGenex filed with the SEC on June 13, 2017 in connection with its stockholder vote on matters relating to the proposed merger. Additional information regarding OncoGenex’s executive officers and directors is available in OncoGenex’s proxy statement on Schedule 14A, filed with the SEC on April 21, 2016. Stockholders are able to obtain this information by reading the final proxy statement/prospectus/information statement.

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SIGNATURES

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

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EXHIBIT INDEX

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