Dual Inhibition of HIF-1α and HIF-2α as a Promising Treatment for VHL-Associated Hemangioblastomas: A Pilot Study Using Patient-Derived Primary Cell Cultures

Background: Von Hippel-Lindau (VHL) disease, a hereditary cancer syndrome, is characterized by mutations in the VHL gene, which result in the stabilization of hypoxia-inducible factors (HIF)-1α and -2α, ultimately leading to the development of highly vascularized tumors, such as hemangioblastomas of central nervous system (CNS-HBs). The standard treatment for these brain tumors is neurosurgical resection. However, multiple surgeries are often required due to tumor recurrence, increasing the risk of neurological sequelae. Therefore, developing pharmacological therapies is essential for reducing the need for repeated surgeries and offering alternatives for unresectable CNS-HBs. Belzutifan (Welireg™), a selective HIF-2α inhibitor and the only FDA-approved non-surgical option, has shown limited efficacy in CNS-HBs, highlighting the need for alternative therapeutic strategies. Results: In this study, 9 primary cell cultures were successfully established and characterized from CNS-HB tissue samples of 11 VHL patients, revealing a composition predominantly of stromal cells and pericytes, and a lower proportion of endothelial cells. Most primary HB cells showed significantly higher positivity (45–90%) for both HIF-1α and HIF-2α isoforms compared to primary glioblastoma cells. This overexpression was subsequently confirmed at both mRNA and protein levels, where HIF-1α showed a slight predominance. Furthermore, the therapeutic potential of acriflavine (ACF), a simultaneous HIF-1α/HIF-2α inhibitor with proven antitumor effects against glioblastoma, was evaluated in these patient-derived primary HB cells. ACF treatment markedly decreased HB cell proliferation and viability, induced G2/M cell cycle arrest, and mainly triggered necrotic cell death. Conclusions: These results suggest that inhibiting both HIF-1α and HIF-2α simultaneously may be more effective in controlling CNS hemangioblastoma progression than targeting HIF-2α alone. Our study provides new insights into the molecular mechanisms driving VHL-associated hemangioblastoma growth and supports the potential clinical application of targeting both HIF-α isoforms as a promising non-invasive therapeutic strategy.