FibroGen and Regeneron Partner for Immuno-Oncology Clinical Trials

FibroGen, Inc. has announced a new clinical trial supply agreement with Regeneron Pharmaceuticals to study the effects of its immuno-oncology assets, FG-3165 and FG-3175, in combination with Regeneron’s anti-PD-1 therapy, LIBTAYO® (cemiplimab), in patients with various solid tumors. This collaboration aims to explore innovative treatments for selected solid tumors by leveraging the unique mechanisms of FG-3165 and FG-3175, which have shown promise in preclinical studies.

FG-3165 is an anti-galectin 9 (Gal9) monoclonal antibody. Gal9 is known to bind to multiple immune checkpoints on lymphocytes, which play a critical role in suppressing the activation of T and natural killer (NK) cells. By targeting Gal9, FG-3165 helps to boost the immune system's ability to fight cancer cells. FG-3175, on the other hand, targets the c-c motif chemokine receptor 8 (CCR8), a receptor commonly overexpressed on T regulatory cells in solid tumors. FG-3175 works by depleting these immunosuppressive cells within the tumor microenvironment, thereby enhancing the anti-tumor response.

“We are thrilled to partner with Regeneron Pharmaceuticals to test these innovative combination therapies for solid tumors,” said Deyaa Adib, M.D., Chief Medical Officer at FibroGen. “The complementary mechanisms of action for FG-3165 and FG-3175 in combination with cemiplimab could potentially lead to better clinical outcomes for patients.”

Under this agreement, Regeneron will supply the necessary drugs for the trials, while FibroGen will sponsor each Phase 1 monotherapy and combination trial. Both companies will retain rights to their respective compounds whether used as monotherapies or in combination therapies. This collaboration aims to build on the promising preclinical data that suggests FG-3165 and FG-3175 can effectively complement PD-1 inhibitors like LIBTAYO®.

Additionally, FibroGen announced that the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for FG-3165 for use in patients with solid tumors, with plans to begin a Phase 1 trial in the second half of 2024. An IND application for FG-3175 is expected to be submitted in 2025.

FG-3165 targets Gal9, known for its role in suppressing immune responses by signaling through multiple immune checkpoints such as TIM3, VISTA, and PD-1. The antibody specifically binds to Gal9 with high affinity, inhibiting its ability to cause lymphocyte cell death and thus enhancing the activation of tumor-killing cells.

FG-3175 targets CCR8, a receptor primarily found on immunosuppressive T regulatory cells in various tumor types. By binding to CCR8, FG-3175 aims to deplete these cells through antibody-dependent cellular cytotoxicity (ADCC), boosting the anti-tumor immune response. This dual mechanism of action enhances anti-tumor activity and could improve clinical outcomes in tumors like breast, colorectal, ovarian, and melanoma.

FibroGen is committed to advancing innovative cancer treatments, as evidenced by its diverse portfolio. Its other key products include Pamrevlumab for pancreatic cancer and Roxadustat for anemia in chronic kidney disease, among others. The company continues to push the boundaries of cancer biology to deliver new therapeutic options for patients.

This partnership with Regeneron marks a significant step in FibroGen’s mission to develop novel therapies that harness the power of the immune system to fight cancer. The upcoming clinical trials will be crucial in determining the efficacy and safety of these promising new treatments.