FibroGen Announces Presentation of Positive Interim Data from the Phase 1b Study of FG-3246 (FOR46) in Combination with Enzalutamide in Patients with Metastatic Castration Resistant Prostate Cancer (mCRPC) at the 2024 American Society of Clinical Oncology

• FG-3246 and enzalutamide combination therapy led to a median radiographic progression free survival (rPFS) of 10.2 months in biomarker unselected patients
  
• FG-3246 demonstrated an acceptable safety profile; adverse events consistent with those observed in other antibody drug conjugate therapies with a MMAE payload
  
• Recommended Phase 2 dose of FG-3246 was established at 2.1 mg/kg every 3 weeks in combination with enzalutamide given at the standard dose of 160 mg daily
  

SAN FRANCISCO, May 23, 2024 (GLOBE NEWSWIRE) -- FibroGen, Inc. (NASDAQ: FGEN) today announced positive interim results from the dose escalation portion of the investigator-sponsored Phase 1b/2 study conducted by the University of California San Francisco of FG-3246 (FOR46), a potential first-in-class anti-CD46 antibody drug conjugate (ADC) with a MMAE-containing payload, in combination with enzalutamide in patients with metastatic castration resistant prostate cancer (mCRPC) at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting.

“We are excited to announce that FG-3246 in combination with enzalutamide in patients with mCRPC demonstrated clinically meaningful early signals of efficacy,” commented Deyaa Adib, M.D., Chief Medical Officer of FibroGen. “These data further validate and build upon the encouraging activity we observed in the recently reported Phase 1 monotherapy data of FG-3246, as well as in preclinical models where the combination of FG-3246 with enzalutamide enhanced its tumor cytotoxic activity. We look forward to continuing our collaboration with the University of California San Francisco and plan to provide additional clinical data from this trial when available.”

The presentation includes data from 17 biomarker unselected patients in the dose escalation portion of the trial. Eligibility criteria for the trial included patients who received at least one prior androgen receptor signaling inhibitor (ARSI) while patients who were treated with prior chemotherapy in the castration resistant setting were excluded. Over 70% of the patients in the study received at least two prior ARSIs, which included prior enzalutamide treatment. Dose escalation was explored with and without prophylactic granulocyte colony-stimulating factor (G-CSF) support. The primary endpoint was determination of the maximally tolerated dose (MTD) of FG-3246 in combination with enzalutamide. The combination treatment demonstrated an encouraging preliminary estimate of median radiographic progression free survival (rPFS) of 10.2 months. The MTD was established at 2.1 mg/kg ABW, with primary G-CSF prophylaxis, in combination with enzalutamide 160 mg/day.