The purpose of this study is to assess the safety and tolerability of mRNA-4106 monotherapy and of mRNA-4200 in combination with checkpoint inhibitor therapy in participants with solid tumors.
Arm 1: Histologically confirmed advanced or metastatic cancer (melanoma, non-small cell lung cancer (NSCLC), hepatocellular carcinoma (HCC), esophageal carcinoma, head and neck squamous cell carcinoma (HNSCC), urinary bladder cancer (UBC), colon/rectal adenocarcinomas, gastric, ovarian, cervical, and endometrial carcinomas) with measurable disease as determined by Response Evaluation Criteria In Solid Tumors volume 1.1 (RECIST v1.1) and have completed or refused all standard therapies (no limit to prior lines of therapy). Participants must have a tumor lesion amenable to biopsy, or alternatively archival tumor tissue is acceptable as long as the collection date is within one year of the enrollment date.
Arm 2: Histologically confirmed advanced or metastatic cancer (melanoma, NSCLC, esophageal carcinoma, HNSCC, urothelial/bladder carcinoma, gastric, colon/rectal adenocarcinomas, ovarian, cervical, and endometrial carcinomas [Note: HCC not included]) with measurable disease as determined by RECIST v1.1 and have completed or refused all standard therapies (no more than 5 prior lines of therapy). Participants must have a tumor lesion amenable to biopsy, or alternatively archival tumor tissue is acceptable if no intervening systemic therapy was received.
Arm 2: Participant life expectancy of ≥90 days.
Arm 1 and Arm 2: Participant has an Eastern Cooperative Oncology Group performance status of ≤1.
Arm 1 and Arm 2: Participant has active central nervous system tumors or metastases
Arm 1 and Arm 2: Participant has received treatment with prohibited medications/treatments (that is, concurrent anticancer therapy including other chemotherapy, hormonal anticancer therapy, biologic therapy, or immunotherapy) or investigational agents within 5 half-lives or 14 days prior to the first day of study treatment (Cycle 1 Day 1), whichever is shorter.
Arm 1 and Arm 2: Participant has required the use of immunosuppressive doses of systemic steroids or absorbed topical steroids (doses >10 milligrams [mg] prednisone daily equivalent) within 2 weeks before study treatment administration or currently requiring maintenance doses of >10 mg prednisone or equivalent per day.
Arm 1 and Arm 2: Participant has any plan to receive a live attenuated vaccine during study treatment or has received a live vaccine within 30 days before the first dose of study treatment.