July 16, 2020
+1 617 526 6000 (t)
+1 617 526 5000 (f)
Pandion Therapeutics Holdco LLC
134 Coolidge Avenue
Watertown, MA 02472
Pandion Therapeutics, Inc. Registration Statement on Form S-1
Ladies and Gentlemen:
This opinion is furnished to you in
connection with a Registration Statement on Form S-1 (File No. 333-239500) (the Registration Statement) filed with the Securities and Exchange
Commission (the Commission) under the Securities Act of 1933, as amended (the Securities Act), for the registration of 8,050,000 shares of Common Stock, par value $0.001 per share (the Shares), of Pandion
Therapeutics, Inc., a Delaware corporation (the Company), to be formed upon the statutory conversion of Pandion Therapeutics Holdco LLC from a Delaware limited liability company into a Delaware corporation (the
Conversion), including 1,050,000 Shares issuable upon exercise of an option granted by the Company.
The Shares are to be sold by the Company
pursuant to an underwriting agreement (the Underwriting Agreement) to be entered into by and among the Company and Goldman Sachs & Co. LLC, Morgan Stanley & Co. LLC and SVB Leerink LLC, as representatives of the several
underwriters named in the Underwriting Agreement, the form of which has been filed as Exhibit 1.1 to the Registration Statement.
We are acting as
counsel for the Company in connection with the issue and sale by the Company of the Shares. We have examined signed copies of the Registration Statement as filed with the Commission. We have also examined and relied upon the Underwriting Agreement,
minutes of meetings and actions of the stockholders and the Board of Directors of the Company as provided to us by the Company, stock record books of the Company as provided to us by the Company, the Certificate of Incorporation and Bylaws of the
Company, each as restated and/or amended to date, and such other documents as we have deemed necessary for purposes of rendering the opinions hereinafter set forth.
In our examination of the foregoing documents, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as
originals, the conformity to original documents of all documents submitted to us as copies, the authenticity of the originals of such latter documents and the legal competence of all signatories to such documents.
We express no opinion herein as to the laws of any state or jurisdiction other than the General Corporation Law of the State of Delaware and the federal laws
of the United States of America.
Based upon and subject to the foregoing, we are of the opinion that the Shares have been duly authorized for issuance
and, following effectiveness of the Conversion, when the Shares are issued and paid for in accordance with the terms and conditions of the Underwriting Agreement, the Shares will be validly issued, fully paid and nonassessable.
Please note that we are opining only as to the matters expressly set forth herein, and no opinion should be inferred as to any other matters. This opinion is
based upon currently existing statutes, rules, regulations and judicial decisions, and we disclaim any obligation to advise you of any change in any of these sources of law or subsequent legal or factual developments which might affect any matters
or opinions set forth herein.