CTNI-82. BELZUTIFAN TREATMENT OF VHL-ASSOCIATED CENTRAL NERVOUS SYSTEM HEMANGIOBLASTOMA

Abstract Von Hippel-Lindau (VHL) disease is caused by pathogenic variants in the VHL gene. Abnormal function of VHL protein leads to accumulation of HIF-α and the engagement of hypoxia-sensitive genes with oncogenic effects. VHL is associated with tumors in multiple organs. Belzutifan is an oral selective inhibitor of hypoxia-inducible factor 2 alpha. Belzutifan was approved in 2021 as a targeted therapy for VHL-associated CNS hemangioblastomas, renal cell carcinomas, and pancreatic neuroendocrine tumors. Here, we report on our institutional clinical experience with belzutifan for VHL-associated CNS hemangioblastomas. From October 2021 to May 2024, thirteen adults (9 female, 4 male, median age 40) were treated. Median duration of therapy was 24 months. Seven had a partial radiographic response after median of 3 months; one patient had a partial response; 1 patient had progressive disease on belzutifan. Four patients have been taking belzutifan for less than 3 months, and do not have follow-up imaging to assess response. The most common adverse effect was fatigue (7 patients). Four patients experienced anemia and 2 experienced hypoxia. Three patients discontinued belzutifan due to adverse effects. One patient had to take multiple medication pauses, due to seizure and kidney injury, but resumed treatment with dose reduction. Nine patients remain on therapy. Based on this data, belzutifan is often well-tolerated and associated with durable radiographic responses. Toxicity profile among our patients was similar to that encountered in the clinical trial leading to approval of the agent. These findings provide real-world data supporting continued use of belzutifan in this patient population, with an awareness of potential adverse reactions. Future studies should assess continued radiographic response, sex differences, and effects after long-term use.