177Lu-BetaBart in Patients With Relapsed/Refractory, Locally Advanced Inoperable, or Metastatic Solid Tumors

The purpose of this study is to establish the safety profile, biodistribution, pharmacokinetics (pk), and radiation dosimetry of 177Lu-BetaBart, to determine the maximum tolerated dose (MTD) and/or recommended Phase 2 dose (RP2D), and to evaluate preliminary anti-tumor activity in select patient populations. The study is divided into 2 phases. Phase 1 is the dose escalation phase to establish the safety profile of 177Lu-BetaBart and to determine the MTD and/or RP2D of 177Lu-BetaBart using a Bayesian Optimal Interval (BOIN) design. Phase 2a is the dose expansion phase at the RP2D to confirm the safety of the MTD and/or RP2D and to evaluate preliminary anti-tumor activity of 177Lu-BetaBart in select patient populations using a probability of success design for the objective response rate (ORR) based on a Bayesian beta-binomial design. Participants ≥ 18 years of age with castration-resistant prostate cancer (CRPC), colorectal cancer (CRC), non-small-cell lung cancer (NSCLC), small-cell lung cancer (SCLC), head and neck squamous cell carcinoma (HNSCC), ovarian cancer, cervical cancer, endometrial cancer, triple negative breast cancer (TNBC), or esophageal squamous cell carcinoma (ESCC) who have documented disease progression during or after their most recent line of anticancer therapy will be eligible to enroll. CRC will be capped at 33% of enrollment per cohort. Each phase consists of a Screening Period, a Treatment and Imaging Period, and a Safety and Long-term Follow-up Period.