A Phase 1, Open-Label Study to Evaluate the Safety, Pharmacokinetics, and Pharmacodynamics of GB-4362 Administered With Enfortumab Vedotin and Pembrolizumab in Participants With Advanced Urothelial Cancer

Summary

The purpose of this study is to evaluate the safety and tolerability of an investigational drug called GB-4362 when it is given together with enfortumab vedotin and pembrolizumab in adults with advanced or metastatic urothelial cancer. GB-4362 is a monoclonal antibody designed to bind and neutralize free monomethyl auristatin E (MMAE), a chemotherapy payload released from enfortumab vedotin that is associated with side effects such as peripheral neuropathy.

Detailed description

This is a Phase 1, open-label, multicenter, dose-finding study designed to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of GB-4362 administered in combination with standard-of-care enfortumab vedotin and pembrolizumab in participants with locally advanced or metastatic urothelial cancer. Enfortumab vedotin is an antibody-drug conjugate containing the cytotoxic payload monomethyl auristatin E (MMAE). Systemic exposure to unconjugated (free) MMAE has been associated with dose-limiting toxicities, including peripheral neuropathy. GB-4362 is a monoclonal antibody designed to selectively bind and neutralize free MMAE in circulation, with the goal of reducing off-target toxicity while preserving the anti-tumor activity of enfortumab vedotin. The study consists of two parts: dose escalation and dose expansion. Multiple dose levels of GB-4362 will be evaluated using a cohort-based escalation design to assess safety, identify dose-limiting toxicities, and characterize PK and PD, including the extent of free MMAE reduction. Dose escalation decisions will be reviewed by a Safety Monitoring Committee. Following dose escalation, a dose expansion phase will enroll additional participants at the selected GB-4362 dose level to further evaluate safety, PK and PD. Exploratory assessments will include evaluation of peripheral neuropathy, dose modifications of enfortumab vedotin, and descriptive analyses of anti-tumor activity.

Arms & interventions

• DrugGB-4362

  GB-4362 is an investigational monoclonal antibody

• Drugenfortumab vedotin (EV)

  Enfortumab vedotin is an antibody-drug conjugate targeting Nectin-4 that delivers the cytotoxic payload monomethyl auristatin E (MMAE).

• DrugPembrolizumab

  Pembrolizumab is a programmed death-1 (PD-1) immune checkpoint inhibitor administered as standard-of-care therapy for advanced urothelial cancer.

Outcome measures

Eligibility criteria