The purpose of this platform study is to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of novel RAS(ON) inhibitors combined with Standard(s) of Care (SOC) or with novel agents.

The current subprotocols include the following:

Subprotocol A: RMC-6236 + 5-fluorouracil-based regimens

Subprotocol B: RMC-6236 + cetuximab with or without mFOLFOX6

Subprotocol C: RMC-6236 + gemcitabine + nab-paclitaxel

Subprotocol D: RMC-9805 with or without RMC-6236 + 5-fluorouracil-based regimens

Subprotocol E: RMC-9805 with or without RMC-6236 + cetuximab with or without mFOLFOX6

Subprotocol F: RMC-9805 with or without RMC-6236 + gemcitabine + nab-paclitaxel

The platform study design allows combinations of RAS(ON) inhibitors with other anticancer agents to be evaluated in patients with RAS-mutated solid tumors with a focus on GI cancers.

This is an open-label platform study to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of novel RAS(ON) inhibitors combined with Standard of Care (SOC) or with novel agents, and to define the Recommended Phase 2 Dose and Schedule (RP2DS). Enrollment of patients with RAS mutations will be specified in each subprotocol.

Subprotocol A is an open-label, multicenter study of RMC-6236 in combination with 5-fluorouracil-based regimens in patients with treatment-naïve unresectable or metastatic colorectal cancer or treatment-naïve metastatic pancreatic ductal adenocarcinoma. Subprotocol B is an open-label, multicenter study of RMC-6236 in combination with cetuximab with or without mFOLFOX6 in patients with unresectable or metastatic colorectal cancer or patients with previously treated or treatment-naïve metastatic pancreatic ductal adenocarcinoma. Subprotocol C is an open-label, multicenter study of RMC-6236 in combination with gemcitabine and nab-paclitaxel in patients with treatment-naïve metastatic pancreatic ductal adenocarcinoma. Subprotocol D is an open-label, multicenter study of RMC-9805 with or without RMC-6236 in combination with 5-fluorouracil-based regimens in patients with RAS G12D-mutant unresectable or metastatic colorectal cancer or metastatic pancreatic ductal adenocarcinoma. Subprotocol E is an open-label, multicenter study of RMC-9805 with or without RMC-6236 in combination with cetuximab-based therapies with or without mFOLFOX6 in patients with RAS G12D-mutant unresectable or metastatic colorectal cancer or metastatic pancreatic ductal adenocarcinoma. Subprotocol F is an open-label, multicenter study of RMC-9805 with or without RMC-6236 in combination with gemcitabine and nab-paclitaxel in patients with RAS G12D-mutant metastatic pancreatic ductal adenocarcinoma.

Each subprotocol consists of two parts: Part 1 - Dose Exploration and Part 2 - Dose Expansion.

Inclusion Criteria:

All Patients (unless otherwise noted):

• ≥ 18 years of age
• ECOG PS is 0 to 1
• Adequate organ function as outlined by the study
• Pathologically or cytologically documented pancreatic carcinoma or poorly differentiated pancreatic carcinoma with metastatic disease or RAS-mutated, histologically or cytologically confirmed colorectal adenocarcinoma with documented unresectable or metastatic disease (Subprotocol A, B, and C)
• Presence of RAS G12D mutation (Subprotocol D, E, F)

Exclusion Criteria:

All Patients:

• Primary central nervous system (CNS) tumors
• Impaired gastrointestinal (GI) function that may significantly alter the absorption of RMC drugs
• Major surgery within 28 days of first dose

Other inclusion/exclusion criteria may apply.