X0306 4 2022-12-09 0 0001718852 Prometheus Biosciences, Inc. RXDX 0001734751 Stenhouse Mark C/O PROMETHEUS BIOSCIENCES, INC. 3050 SCIENCE PARK ROAD SAN DIEGO CA 92121 0 1 0 0 Chief Operating Officer Common Stock 2022-12-09 4 A 0 9811 0.00 A 26442 D Stock Option (Right to Buy) 110.20 2022-12-09 4 A 0 34085 0.00 A 2032-12-08 Common Stock 34085 34085 D Award of restricted stock units ("RSUs") granted under the Issuer's 2021 Incentive Award Plan. Each RSU entitles the Reporting Person to receive one share of Issuer common stock upon vesting. The award will vest and settle with respect to twenty-five percent (25%) of the total number of RSUs on December 9, 2023, 2024, 2025 and 2026, subject to the Reporting Person's continued service with the Issuer through each vest date. Includes a total of 2,631 shares of the Issuer's common stock acquired pursuant to the Issuer's Employee Stock Purchase Plan. 25% of the shares subject to the option will vest on December 9, 2023, and 1/48th of the shares subject to the option will vest monthly thereafter, subject to the Report Person's continued service with the Issuer through each vest date. /s/ Timothy K. Andrews, attorney-in-fact for Mark Stenhouse 2022-12-13