A Study of MK-1084 in KRAS Mutant Advanced Solid Tumors (MK-1084-001)

Inclusion Criteria

• Inclusion Criteria: For all participants: - Has measurable disease by RECIST 1.1 criteria - Has adequate organ function - Male participants agree to protocol-specified contraception requirements including refraining from donating sperm and using protocol-specified contraceptives unless confirmed to be azoospermic - Female participants must not be pregnant or breastfeeding, and must agree to protocol-specified contraceptive requirements and must have a negative highly sensitive pregnancy test within 24 hours (for a urine test) or 72 hours (for a serum test) before the first dose of study intervention For Arm 1 - Has locally advanced unresectable or metastatic solid-tumor malignancy with histologically OR blood-based confirmation of KRAS G12C mutation who has received at least 1 line of therapy for systemic disease For Arm 2 - Has an untreated metastatic non-small cell lung cancer (NSCLC) with histologically OR blood-based confirmation of KRAS G12C mutation and histologic confirmation of programmed cell death ligand 1 (PD-L1) tumor proportion score (TPS) ≥1% For Arm 3 - Has locally advanced unresectable or metastatic solid-tumor malignancy with histologically or blood-based confirmation of KRAS G12C mutation who has received at least 1 line of therapy for systemic disease Expansion Group A: 2L+NSCLC - Has histologically or cytologically confirmed diagnosis of unresectable or metastatic NSCLC with histological or blood-based confirmation of KRAS G12C mutation and submits archival tumor sample - Previous treatment failure of at least 1 line of systemic therapy Expansion Group B - Has locally advanced unresectable or metastatic solid-tumor malignancy, excluding NSCLC or CRC, with histologically or blood- based confirmation of KRAS G12C mutation who has received at least 1 line of therapy for systemic disease Arm 4 only - Has an untreated advanced or metastatic nonsquamous NSCLC with histologically or blood-based confirmation of KRAS G12C mutation Arm 5 only - Histologically or cytologically confirmed diagnosis of locally advanced unresectable or metastatic colorectal adenocarcinoma and with histologically or blood-based confirmation of KRAS G12C mutation - Previous treatment failure of one or 2 previous line(s) of systemic therapy Arm 6 only - Locally advanced unresectable or metastatic colorectal adenocarcinoma with histologically or blood-based confirmation of KRAS G12C mutation Exclusion Criteria: - Has received chemotherapy, definitive radiation, or biological cancer therapy within 4 weeks (2 weeks for palliative radiation) before first dose of study intervention - Has a history of second malignancy, unless potentially curative treatment has been completed with no evidence of malignancy for 5 years - Has clinically active central nervous system (CNS) metastases and/or carcinomatous meningitis - Has an active infection requiring systemic therapy - Known history of HIV infection or. has a known history of Hepatitis B virus or known active Hepatitis C virus infection - Has a history of interstitial lung disease, noninfectious pneumonitis requiring active steroid therapy, or ongoing pneumonitis - Has an active autoimmune disease requiring systemic therapy - Has not fully recovered from any effects of major surgical procedure without significant detectable infection - Has one or more of the following ophthalmological findings/conditions: intraocular pressure >21 mm Hg and/or any diagnosis of glaucoma; diagnosis of central serous retinopathy, retinal vein occlusion, or retinal artery occlusion and/or a diagnosis of retinal degenerative disease - Has received live or live-attenuated vaccine within 4 weeks of study start Arm 4 Only - Is unable to interrupt aspirin or other nonsteroidal anti-inflammatories (NSAIDs), other than an aspirin dose ≤1.3 grams per day, for at least 2 days (5 days for long-acting agents [for example, piroxicam]) before, during, and for at least 2 days after administration of pemetrexed. - Is unable/unwilling to take folic acid, vitamin B12, and dexamethasone