FibroGen Initiates Phase 2 Monotherapy Trial of FG-3246, a First-in-Class CD46 Targeting ADC, in Metastatic Castration-Resistant Prostate Cancer

Core Insights - FibroGen has initiated a Phase 2 monotherapy, dose-optimization trial for FG-3246, targeting metastatic castration-resistant prostate cancer (mCRPC) [1][2] - The trial will also evaluate FG-3180, a companion PET imaging agent, for its ability to identify mCRPC lesions and predict responses to FG-3246 [1][2] Company Developments - FibroGen has completed its transformation into a U.S.-focused organization and has a cash runway extending into 2028 [2] - The Phase 2 trial will enroll 75 patients who have progressed after androgen receptor signaling inhibitor (ARSI) treatment and have not received chemotherapy [2][6] - Interim analysis results from the Phase 2 study are expected in the second half of 2026 [2][6] Clinical Trial Details - The Phase 2 trial is a randomized, open-label study designed to determine the optimal dose of FG-3246 based on efficacy, safety, and pharmacokinetics [2][5] - Patients will be randomized to receive one of three doses: 1.8, 2.4, or 2.7 mg/kg AJBW of FG-3246 [2] - Secondary endpoints include radiographic progression-free survival (rPFS) and prostate-specific antigen (PSA) response rates [2][6] Product Information - FG-3246 is a first-in-class fully human antibody-drug conjugate (ADC) targeting CD46, which is highly expressed in prostate cancer [4][8] - The drug is linked to the anti-mitotic agent MMAE, which has shown anti-tumor activity in both preclinical and clinical studies [4][8] Market Context - Prostate cancer is the second most common malignancy in men, with approximately 13% of men diagnosed during their lifetime [7] - There are about 65,000 drug-treatable mCRPC cases annually in the U.S., with a 5-year survival rate of approximately 30% [7]