By Fineline Cube 
FibroGen, Inc. (NASDAQ: FGEN) announced today the start of a randomized, open‑label Phase 2 monotherapy trial (NCT06842498) evaluating FG‑3246, a first‑in‑class antibody‑drug conjugate (ADC) that targets CD46‑expressing tumor lesions in patients with metastatic castration‑resistant prostate cancer (mCRPC). The study also incorporates FG‑3180, a companion PET imaging agent that shares the same CD46‑specific antibody, to assess its diagnostic and predictive performance.
Trial Design & Objectives
| Element | Detail |
|---|---|
| Phase | 2 (dose‑optimization) |
| Population | 75 mCRPC patients who progressed after androgen‑receptor‑signaling‑inhibitor (ARSI) therapy and have not received chemotherapy |
| Randomization | 3 dose arms (dose‑level 1, 2, 3) |
| Primary Endpoint | Determination of the optimal dose for Phase 3 based on efficacy, safety, and PK |
| Secondary Endpoints | • Radiographic progression‑free survival (rPFS) • PSA 50 response • PSA 90 response |
| Interim Analysis | Planned after 12 patients per arm complete 12 weeks or discontinue; expected in H2 2026 |
FG‑3246: First‑In‑Class CD46‑Targeted ADC
- Mechanism – FG‑3246 couples a humanized anti‑CD46 antibody to a potent cytotoxic payload, delivering the drug directly to CD46‑positive tumor cells while sparing normal tissue.
- Preclinical Data – Demonstrated robust tumor‑cell killing in CD46‑expressing prostate and other solid‑tumor models, with a favorable safety profile.
- Clinical Promise – If successful, FG‑3246 could become the first ADC approved for mCRPC, a disease with limited post‑ARSI therapeutic options.
FG‑3180: Companion PET Imaging Agent
- Design – FG‑3180 utilizes the same CD46‑specific antibody as FG‑3246, labeled with a positron‑emitting radionuclide for high‑resolution imaging.
- Purpose – To identify CD46‑positive lesions, quantify tumor burden, and predict which patients are most likely to respond to FG‑3246 therapy.
- Potential Impact – Provides a precision‑medicine framework, aligning diagnostics with targeted therapy—a key trend in oncology drug development.
Market & Strategic Context
- The global prostate‑cancer therapeutics market is projected to exceed $20 billion by 2030, driven by unmet needs in the mCRPC space.
- ADCs have emerged as a transformative modality, with recent approvals for HER2‑positive breast cancer and HER2‑negative breast cancer.
- FibroGen’s dual‑agent strategy positions the company to capture both therapeutic and diagnostic revenue streams, potentially accelerating regulatory approval and market adoption.
Forward‑Looking Statements
FibroGen cautions that the Phase 2 trial results will inform dose selection for a planned Phase 3 study and that clinical and regulatory milestones are subject to change based on emerging data.-Fineline Info & Tech