Study of mRNA-4359 Administered Alone and in Combination With Immune Checkpoint Blockade in Participants With Advanced Solid Tumors

Males or females ≥18 years of age who have provided written informed consent prior to completing any study-specific procedure. For Arm 2d, participants ≥12 years are eligible with informed consent/assent.

Dose Escalation (Arm 1a): Participant has histologically confirmed locally advanced or metastatic cancer (cutaneous melanoma, NSCLC, non-muscle invasive bladder cancer, head and neck squamous cell carcinoma, microsatellite stable colorectal cancer [MSS CRC], basal cell carcinoma, or triple negative breast cancer) with measurable disease as determined by RECIST v1.1. Arm 1a participants must have received, and then progressed, relapsed, or been intolerant to, or ineligible for, at least 1 standard treatment regimen in the advanced or metastatic setting. Participants with a known driver mutation must have also received or been offered a mutation-directed therapy, where indicated. Participants must have a tumor lesion amenable to biopsy and must have another lesion that can be followed for response.

Dose Confirmation (Arm 1b): Participant has histologically confirmed locally advanced or metastatic, and CPI refractory melanoma or locally advanced or metastatic, and CPI refractory NSCLC with measurable disease as determined by RECIST v1.1 who has disease progression after, at least 1 line of standard therapy (no limit to prior lines of therapy), and has been treated with or refused standard of care treatment. Participants in PD arm Group 2 must also have PD-L1 TPS ≥1%. Participants must have primary refractory or acquired secondary resistance to prior immune checkpoint treatments. Primary refractory is defined as prior exposure to anti-programmed death-1 (PD-1)/PD-L1 antibody for at least 6 weeks but no more than 6 months with demonstration of progression on 2 separate scans at least 4 weeks apart but no more than 12 weeks apart and progression occurring within 6 months after first dose of anti-PD-1 antibody. Acquired secondary resistance must have confirmed objective response or prolonged stable disease (SD) (>6 months), followed by disease progression in the setting of ongoing treatment and confirmed progression on scans at least 4 weeks apart. Participants must have a tumor lesion amenable to biopsy and must have another lesion that can be followed for response.

For NSCLC participants with known EGFR, ALK, proto-oncogene tyrosine-protein kinase reactive oxygen species (ROS1), or other actionable mutations for which there are approved targeted therapies, participants must have received prior approved targeted therapy or have been offered and declined approved targeted therapy.