FibroGen announced positive results from a Phase 1 study of FG-3246, an antibody-drug conjugate targeting CD46, in patients with metastatic castration-resistant prostate cancer (mCRPC). The study, published in the Journal of Clinical Oncology, demonstrated encouraging anti-cancer activity and an acceptable safety profile. A Phase 2 monotherapy dose optimization study is expected to begin by mid-2025.
This development is potentially important for patients with mCRPC who have limited treatment options after progressing on current therapies. FG-3246 targets CD46, offering a novel, non-PSMA-based approach to treating this aggressive form of prostate cancer. The positive Phase 1 data suggest that FG-3246 could become a valuable addition to the treatment landscape, particularly given the high unmet need in this patient population.
The Phase 1 study demonstrated a maximally tolerated dose of 2.7 mg/kg. Common adverse events were typical of MMAE-based ADCs, including infusion reactions, neutropenia, and peripheral neuropathy. Importantly, ocular adverse events were infrequent. The study observed a 20% confirmed objective response rate and an 80% disease control rate in the RECIST-evaluable patient set. A PSA50 response rate of 36% was observed in evaluable patients. The median radiographic progression-free survival was 8.7 months. Furthermore, most baseline tumors tested positive for CD46 expression. Responders showed a higher frequency of effector T cells and a lower frequency of immunosuppressive myeloid cells. A combination study of FG-3246 with enzalutamide is ongoing, with topline Phase 2 results expected in the second half of 2025.
The promising Phase 1 results support further investigation of FG-3246 as a potential treatment for mCRPC. The upcoming Phase 2 study will be crucial in optimizing the dose and further characterizing the efficacy and safety profile. The outcome of this trial and the parallel combination study with enzalutamide will significantly influence the future development trajectory of FG-3246 and its potential to address the unmet needs in mCRPC treatment.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
