SumMET: Study of [225Ac]Ac-FL-261 in Participants With Solid Tumors Overexpressing c-MET

Phase 1: Dose Escalation \[225Ac\]Ac-FL-261 will be administered at increasing doses in participants with non-squamous non-small cell lung cancer (ns-NSCLC) to identify the maximum tolerated dose (MTD) based on a BOIN design. Phase 1 - Dose Optimization After Dose Escalation is complete, 2 treatment regimens will be compared to select the optimal treatment regimen (OTR) between them. Phase2 Participants with ns-NSCLC, colorectal cancer, head and neck cancer and cholangiocarcinoma will be enrolled into separate cohorts to estimate the efficacy of \[225Ac\]Ac-FL-261 at the OTR in each indication.