TWO CASES OF VON HIPPEL-LINDAU SYNDROME-ASSOCIATED RETINAL HEMANGIOBLASTOMA TREATED WITH BELZUTIFAN.

Purpose: To describe two cases of retinal hemangioblastoma regression following treatment with belzutifan in patients with von Hippel-Lindau syndrome.

Methods: Clinical information was extracted from the charts and tumor imaging of two patients with von Hippel-Lindau-associated retinal hemangioblastoma.

Results: In Case 1, a 40-year-old man was treated with belzutifan for spine hemangioblastomas after diagnosis of a 2.0 × 2.0 × 1.3 mm left-eye retinal hemangioblastoma temporal to the macula associated with intraretinal edema, subretinal fluid, and mild retinal traction. In Case 2, a 66-year-old woman presented with a right eye 2.0 × 1.5 × 1.3 mm juxtapapillary lesion with subretinal fluid, intraretinal fluid, and nasal traction, and a 4.0 × 3.5 × 1.1 mm inferior midperiphery lesion with subretinal fluid, intraretinal fluid, and active exudation. She was treated for 2.5 years with belzutifan for renal cell carcinoma on the National Institutes of Health trial. The patient in case 1 demonstrated a 10% reduction in largest tumor diameter and 8% reduction in thickness, along with improving subretinal fluid, intraretinal edema, and retinal traction, after 4 weeks of treatment. After 2.5 years of treatment, the patient in Case 2 demonstrated similar margins of her now fibrotic-appearing juxtapapillary lesion with a 45% reduction in thickness, along with resolved subretinal fluid and greatly improved intraretinal fluid and traction. The inferior lesion demonstrated 12.5% reduction in largest diameter, 36% reduction in thickness, and was without active subretinal fluid or exudation. Neither patient demonstrated new lesions while on treatment.

Conclusion: Belzutifan is a promising treatment for retinal hemangioblastoma with the potential for both rapid and sustained tumor regression.