X0306 4 2018-01-04 0 0001290149 Sierra Oncology, Inc. SRRA 0001305641 Parfet Donald R C/O SIERRA ONCOLOGY, INC. 2150 885 WEST GEORGIA ST. VANCOUVER A1 V6C 3E8 BRITISH COLUMBIA, CANADA 1 0 0 0 Common Stock 2018-01-04 4 J 0 3383 0.00 A 390913 I By Donald R. Parfet 2006 Trust, Dated May 1, 2006 Common Stock 2018-01-04 4 J 0 1692 0.00 A 1692 I Apjohn Ventures, LLC Common Stock 2018-01-04 4 J 0 1068 0.00 A 2760 I Apjohn Ventures, LLC Common Stock 2018-01-04 5 J 0 E 2760 0.00 D 0 I Apjohn Ventures, LLC Common Stock 2018-01-04 5 J 0 E 1380 0.00 A 77235 D Common Stock 238419 I By Ann VanDeWater Parfet 2006 Revocable Trust, Dated May 5, 2006 Common Stock 4970 I By wife Common Stock 589 I By Apjohn Group, LLC Represents shares of the issuer's common stock received in connection with a pro rata distribution of shares held by Apjohn Ventures Fund, LP to its limited partners. The reporting person is the trustee of the Donald R. Parfet 2006 Trust, Dated May 1, 2006. The reporting person is a managing member of Apjohn Ventures, LLC ("AVLLC"), and has shared voting and shared dispositive power over the shares held by AVLLC. The reporting person disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. Represents shares of the issuer's common stock received in connection with a pro rata distribution of shares held by Apjohn Ventures Annex Fund LP to its limited partners. Represents a pro rata distribution of shares of the issuer's common stock held by AVLLC to its members. Represents shares of the issuer's common stock received in connection with a pro rata distribution of shares held by AVLLC to its members. The reporting person's wife is the trustee of the Ann VanDeWater Parfet 2006 Revocable Trust, Dated May 5, 2006. The reporting person disclaims beneficial ownership of such securities, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. The reporting person is the managing member of Apjohn Group, LLC ("AGLLC"), and has sole voting and dispositive power over the shares held by AGLLC. The reporting person disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. /s/ Sukhi Jagpal as attorney-in-fact for Donald Parfet 2018-01-05