Exhibit 5.1

November 20, 2009

Poniard Pharmaceuticals, Inc.

7000 Shoreline Court, Suite 270

South San Francisco, CA 94080

Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection with the offering by Poniard Pharmaceuticals, Inc., a Washington corporation (the “Company”), of 3,465,878 shares of the Company’s common stock, par value $0.02 (the “Shares”), pursuant to a Registration Statement on Form S-3, as amended (No. 333-159253) (the “Registration Statement”), filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), the prospectus dated August 19, 2009 (the “Base Prospectus”), and the prospectus supplement dated November 20, 2009 relating to the Shares, filed with the Commission pursuant to Rule 424(b) of the Rules and Regulations of the Securities Act (the “Prospectus Supplement”).  (The Base Prospectus and the Prospectus Supplement are collectively referred to as the “Prospectus.”)  All of the Shares are to be sold by the Company as described in the Registration Statement and the Prospectus.

In connection with this opinion, we have examined and relied upon the Registration Statement and the Prospectus, the Company’s Amended and Restated Articles of Incorporation, the Company’s Amended and Restated Bylaws, as amended, and the originals or copies certified to our satisfaction of such records, documents, certificates, memoranda and other instruments as in our judgment are necessary or appropriate to enable us to render the opinion expressed below.  We have assumed the genuineness and authenticity of all documents submitted to us as originals, and the conformity to originals of all documents submitted to us as copies thereof and the due execution and delivery of all documents where due execution and delivery are a prerequisite to the effectiveness thereof.

On the basis of the foregoing, and in reliance thereon, we are of the opinion that the Shares have been duly authorized and, when issued and sold by the Company in the manner described in the Registration Statement and the Prospectus, will be validly issued, fully paid and nonassessable.

This opinion is limited to matters governed by the Washington Business Corporation Act.

We hereby consent to reference to our firm under the caption “Legal Matters” in the Prospectus and to the filing of this opinion as Exhibit 5.1 to the Registration Statement.  In giving this consent, we do not hereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder nor do we admit that we are experts with respect to any part of the Registration Statement within the meaning of the term “expert” as used in the Securities Act or the related rules and regulations of the Commission promulgated thereunder.

Very truly yours,

/s/ PERKINS COIE LLP

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