X0206 3 2020-07-16 0 0001807901 Pandion Therapeutics, Inc. PAND 0001055951 ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 0 0 1 0 0001760648 OrbiMed Capital GP VII LLC C/O ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 0 0 1 0 0001808744 OrbiMed Genesis GP LLC C/O ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 0 0 1 0 Series B Preferred Stock Common Stock 187855 I See footnote Series B Preferred Stock Common Stock 469637 I See footnote The Series B Preferred Stock is convertible into Common Stock on a 5.0994 for-one basis into the number of shares of Common Stock shown in Column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date. Consists of 187,855 shares of Common Stock issuable upon conversion of Series B Preferred Stock held by OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund"). These securities are held of record by Genesis Master Fund. OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by Genesis Master Fund and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund. This report on Form 3 is jointly filed by OrbiMed Advisors, Genesis GP, and OrbiMed Capital GP VII LLC ("GP VII"). Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. Consists 469,637 shares of Common Stock issuable upon conversion of Series B Preferred Stock held by OrbiMed Private Investments VII, LP ("OPI VII"). These securities are held of record by OPI VII. GP VII is the general partner of OPI VII. OrbiMed Advisors is the managing member of GP VII. By virtue of such relationships, GP VII and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VII. OrbiMed Advisors LLC, By: /s/ Douglas Coon, authorized signatory 2020-07-16 OrbiMed Capital GP VII LLC, By: /s/ Douglas Coon, authorized signatory 2020-07-16 OrbiMed Genesis GP LLC, By: /s/ Douglas Coon, authorized signatory 2020-07-16