Phase 1/1b, Multicenter, Open-LabeL, Study of RMC-9805 in Participants with Advanced KRASG12D-Mutant Solid Tumors

• RMC-9805 is a KRAS G12D inhibitor

In this study, the sponsor and investigators want to learn:

• How much of the study drug can be given with an acceptable level of side effects
• The effects of the study drug (good and bad)
• How much of the study drug / agent is absorbed into the blood and how fast it is removed
• If research tests can be used in the future to predict who will benefit from RMC-9805

This study has 3 periods:

1. Screening/Baseline period (before you begin the study to see if you qualify for the study)
2. Study Treatment period (when you will receive the study drug; this occurs in 21-day cycles)
3. Follow-up period (to check on you after your study treatment is finished)

In addition, this study is divided into 2 parts:

• Part 1 (dose exploration): Small groups of participants will be enrolled one at a time. Each group will receive a higher dose of RMC-9805 than the last group. These groups will be enrolled until the highest tolerated dose of RMC-9805 is identified. Alternative dose levels and schedules for the study drug may also be explored.
• Part 2 (dose expansion): Larger groups of participants will be enrolled one at a time. Each group will receive a dose level and dosing schedule that is deemed safe and tolerable as determined in Part 1. These groups are for collecting more information about the selected dose and/or schedule.
• The effect of food will be evaluated in Part 1 and may be evaluated in Part 2 (Food Effect Cohort). A Food Effect Cohort is for determining if taking RMC-9805 with or without a meal affects how the study drug works.

You will be enrolled in either Part 1 or Part 2. You will be assigned a dose and schedule of RMC-9805 when you start the study. Part 2 will be filled after Part 1 is completed, so the part you are placed into depends on when you enroll. Your study doctor will tell you which Part of the study (Part 1 or Part 2) you would be in.

Your dose of RMC-9805 may be increased later during your participation in the study if higher doses are determined to be safe. For any dose increase, it should be determined by your study doctor that it is in your best interest to do so. If you have side effects at any time, your dose of RMC-9805 may also be decreased, temporarily held, or discontinued.

This is an open-label study, which means that both you and the study doctor will know that you are receiving RMC-9805.