Abstract 5970: Rescuing VHLD missense mutations to prevent or treat renal cell carcinoma

Abstract Von Hippel-Lindau disease (VHLD) is an autosomal dominant cancer syndrome caused by germline mutations that occur throughout the VHL gene, affecting approximately 1 in 36,000 individuals. VHLD most commonly results in clear cell renal cell carcinoma (ccRCC) but can cause pancreatic neuroendocrine tumors and central nervous system hemangioblastomas, depending on the site of mutation. Somatic mutations in VHL are also common features of spontaneous ccRCC. The VHL protein (pVHL) serves as the substrate recognition component of the VCB E3 ubiquitin ligase complex (Elongin B/C, Cullin-2, and Rbx1), which targets hydroxylated HIF-α for proteasomal degradation under normoxic conditions. When VHL is mutated or oxygen is limited, HIF-α accumulates, activating genes such as VEGFA and TGFα that promote angiogenesis and proliferation. pVHL also has HIF-independent functions that are less understood but may contribute to VHLD pathogenesis. Belzutifan, which inhibits HIF-2α activity, has emerged as a valuable treatment for VHLD and spontaneous ccRCC, but not all patients respond, possibly due to cancer-promoting, HIF-independent consequences of VHL loss. This suggests the potential value of targeting pVHL directly.To evaluate how distinct missense mutations affect the canonical HIF-degradation role versus non-canonical functions, we analyzed public databases to identify common VHLD mutations associated with ccRCC versus other VHLD syndromes. We selected mutations distributed across the protein surface, including those disrupting interactions with VCB or HIF. We then generated lentiviruses encoding wild-type, null, and 10 VHLD-associated mutations, and used these to establish a series of isogenic models in VHL-null 786-O cell line. Cell models were characterized for pVHL and HIF-2a expression, as well as a series of non-canonical VHL-regulated phenotypes including control of mitotic integrity and spindle checkpoint activity. We then compared the ability of belzutifan and three pVHL-targeting drugs (VH298, CP4, CP4.29) to reverse phenotypes associated with VHLD mutations or loss. Whereas VH298 disrupts the VHL:HIF interaction interface, the recently described CP4 and its derivative CP4.2 bind a cryptic pocket near Asp197 in pVHL, stabilizing the structure and potentially restoring multiple protein functions. We will discuss activity of these compounds in rescuing essential VHL activities across diverse VHLD mutations, for canonical and non-canonical pathways. The goal of this work is to develop a new therapeutic approach for VHLD patients. Citation Format: Shabnam Pirestani. Rescuing VHLD missense mutations to prevent or treat renal cell carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5970.