X0306 4 2015-07-21 0 0001290149 ProNAi Therapeutics Inc DNAI 0001357522 Thompson Peter A. C/O PRONAI THERAPEUTICS, INC. 2150 ? 885 WEST GEORGIA ST. VANCOUVER A1 V6C 3E8 BRITISH COLUMBIA, CANADA 1 0 0 0 Common Stock 2015-07-21 4 C 0 1725790 A 1725790 I See Footnotes Common Stock 2015-07-21 4 J 0 89159 5.215 A 1814949 I See Footnotes Common Stock 2015-07-21 4 P 0 175000 17.00 A 1989949 I See Footnotes Series D Preferred Stock 2015-07-21 4 C 0 1725790 0.00 D Common Stock 1725790 0 I See Footnotes Each share of the issuer's Series D Preferred Stock automatically converted into 1 share of the issuer's Common Stock on July 21, 2015 in connection with the closing of the issuer's sale of its Common Stock in its firm commitment initial public offering pursuant to a registration statement on Form S-1 (File No. 333-204921) under the Securities Act of 1933, as amended, and had no expiration date. These securities are held of record by OrbiMed Private Investments V, LP ("OPI V"). OrbiMed Capital GP V LLC ("GP V") is the sole general partner of OPI V, and OrbiMed Advisors LLC ("Advisors") is the managing member of GP V. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of and owner of a controlling interest in Advisors. By virtue of such relationships, GP V, Advisors and Isaly may be deemed to have voting and investment power over the securities held by OPI V and as a result may be deemed to have beneficial ownership over such securities. The Reporting Person is an employee of Advisors. Each of GP V, Advisors, Isaly and the Reporting Person 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 or his pecuniary interest therein, if any. This report on Form 4 shall not be deemed an admission that any such entity or person, including the Reporting Person, is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose. Represents shares of Common Stock issued by the issuer in payment of cumulative accrued dividends. /s/ Sukhi Jagpal as attorney-in-fact for Peter Thompson, M.D. 2015-07-21