Exhibit 5.1

DLA Piper LLP (US)

One Liberty Place

1650 Market Street, Suite 5000

Philadelphia, PA  19103-7300

www.dlapiper.com

May 27, 2025

PDS Biotechnology Corporation

303A College Road East

Princeton, NJ 08540

Re: PDS Biotechnology Corporation Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to PDS Biotechnology Corporation, a Delaware corporation (the “Company”), in connection with the filing by the Company of the referenced Registration Statement (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Act”) with the Securities and Exchange Commission pursuant to Rule 415 under the Act.  The Registration Statement relates to the proposed offering and sale of an aggregate of 9,818,340 shares (the “Shares”) of common stock, par value $0.00033 per share (“Common Stock”), issuable upon (i) the exercise of warrants exercisable for an aggregate of 1,000,00 shares of Common Stock (the “Warrants”), and (ii) the conversion of debentures which are convertible for up to an aggregate of 8,818,340 shares of Common Stock (the “Debentures”). The Shares, the Warrants and the Debentures are referred to herein collectively as the “Securities”. The Securities were issued pursuant to a securities purchase agreement between the Company and the buyers named therein dated as of April 30, 2025 (the “Purchase Agreement”). This opinion is being rendered in connection with the filing of the Registration Statement with the Commission.

In connection with this opinion, we have examined and relied upon the Registration Statement and the prospectus contained therein, the Company’s Eighth Amended Restated Certificate of Incorporation, as amended (the “Charter”), the Company’s Third Amended and Restated Bylaws, the Purchase Agreement, and such instruments, documents, certificates and records that we have deemed relevant and necessary for the basis of our opinion hereinafter expressed. In such examination, we have assumed: (i) the authenticity of original documents and the genuineness of all signatures; (ii) the conformity to the originals of all documents submitted to us as copies; (iii) the truth, accuracy and completeness of the information, representations and warranties contained in the records, documents, instruments and certificates we have reviewed; and (iv) the due execution and delivery of all documents where due execution and delivery are a prerequisite to the effectiveness thereof. For purposes of the opinion set forth below, we have assumed that before the Shares are issued the Company does not issue shares of Common Stock or reduce the total number of shares of Common Stock the Company is authorized to issue under the Charter such that the number of unissued shares of Common Stock authorized under the Charter is less than the number of the Shares.

This opinion is limited to the General Corporate Law of the State of Delaware, and we express no opinion with respect to the laws of any other jurisdiction. No opinion is expressed herein with respect to the qualification of the Shares under the securities or blue sky laws of any state or foreign jurisdiction.

Based upon the foregoing, and subject to the qualifications, assumptions, limitations and exceptions stated herein, we are of the opinion that (i) the Shares issuable upon exercise of the Warrants, have been duly authorized and when paid for and issued pursuant to the terms of the Charter and the Warrants, will be validly issued, fully paid and nonassessable, and, (ii) the Shares issuable upon conversion of the Debentures, have been duly authorized and when issued pursuant to the terms of the Charter and the Debentures, will be validly issued and non-assessable.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement and to the reference to this firm under the caption “Legal Matters” in the Registration Statement.

In giving this consent, we do not admit that we are within the category of persons whose consent is required by Section 7 of the Securities Act or the rules and regulations promulgated thereunder by the Commission. This opinion letter is given to you solely for use in connection with the resale of the Shares while the Registration Statement is in effect and is not to be relied upon for any other purpose. Our opinion is expressly limited to the matters set forth above, and we render no opinion, whether by implication or otherwise, as to any other matters relating to the Company, the Securities or the Registration Statement.

Very truly yours,

/s/ DLA Piper LLP (US)