PD-32766T (an Actinium-225 [225Ac] labeled peptide)

This is an open-label, multicenter, Phase 1a/1b study evaluating the theranostic pair 64Cu-PD-32766 Injection (PD-32766D) and 225Ac-PD-32766 Injection (PD-32766T) in adult patients with relapsed or refractory Carbonic Anhydrase IX (CA9)-expressing clear cell renal cell carcinoma (ccRCC). The primary objective is to evaluate the safety and tolerability of PD-32766T, and to characterize its pharmacokinetics and preliminary antitumor activity. Participants will first undergo imaging with PD-32766D to assess CA9 expression. Subjects with positive tumor uptake will be eligible to receive PD-32766T. In Phase 1a, PD-32766T will be administered in an escalating dose levels and schedule determined according to protocol and Safety Review Committee recommendations. In Phase 1b, participants will receive PD-32766T at the recommended dose and schedule identified from Phase 1a to further evaluate safety, tolerability, and preliminary efficacy. A total of up to 60 participants will be enrolled in the study.