This is a phase I/IIa, open-label, multi-center study to evaluate the safety, tolerability, dosimetry, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy of \[212Pb\]Pb-MP0712 in patients with SCLC and other advanced DLL3-expressing solid tumors. The study consists of a dose escalation part, followed by a dose expansion part. Once the recommended radioactive dose(s) \[212Pb\]Pb-MP0712 for further clinical evaluation are determined, the dose expansion part will further characterize the safety, tolerability, and preliminary anti-tumor activity of \[212Pb\]Pb-MP0712. The study will enable evaluation of the safety, dosimetry, PK, and imaging properties of \[203Pb\]Pb-MP0712.
