Abstract A003: Baseline levels of HIF2 target proteins and response to the HIF2α inhibitor NKT2152 in patients with metastatic clear cell renal cell carcinoma

Abstract Background Clear cell renal cell carcinoma (ccRCC) is characterized by inactivation of the von Hippel-Lindau (VHL) gene, leading to hypoxia-inducible factor-2α (HIF2α) upregulation, which drives tumorigenesis. The HIF2α inhibitor (HIF2i) bezutifan is an approved treatment for metastatic ccRCC (mccRCC) and other HIF2i, including NKT2152, have shown clinical activity in early clinical trials. However, not all patients (pts) benefit from HIF2i and biomarkers of response/resistance are needed. Preclinical data suggest that VHL-mutant ccRCCs with lower baseline levels of HIF2 activity may be less likely to respond to HIF2i. Hence, we investigated whether baseline levels of two HIF2 target proteins, glucose transporter-1 (GLUT1) and Cyclin D1, were associated with clinical outcomes in pts with mccRCC treated with NKT2152 as part of a Phase I/II trial (NCT05119335). Methods Dual immunohistochemistry (IHC) for GLUT1 and Cyclin D1 was performed on pretreatment ccRCC tissues from 42 pts. For each marker, AI-based image analysis algorithms were used to assess the percentage of tumor cells (TC) with weak or strong positivity. IHC results were compared across best overall response categories (progressive disease (PD), stable disease (SD), complete/partial response (CR/PR)) and VHL mutation status using the Wilcoxon rank-sum test. To assess the association between the expression of each marker and progression-free survival (PFS), patients were divided into low- and high-expression groups. The Cox-proportional hazards models were then applied to identify optimal expression cutoffs and evaluate statistical significance. Results The percentage of TC with any GLUT1 positivity ranged between 23.1% to 99.5% (median=79.2%). Pts with PD (n=10) had higher percentage of TC with weak GLUT1 positivity compared to pts with SD/CR/PR (n=32) (median 52.2% vs. 31.8%, p = 0.045). At an optimized cutoff, pts with high percentage of TC with weak GLUT1 positivity (n=7, 16.7%) experienced shorter median PFS (56 days, 95% CI: 29-NA vs. 505 days, 95% CI: 167-NA, p=0.054) compared to pts with low percentage (n=35, 83.3%). Among 41 tumors with sequencing data, 33 (80.5%) harbored VHL mutations, including 17 with truncating mutations. The percentage of TC with weak GLUT1 positivity was higher in tumors without VHL truncating mutations compared to tumors with truncating mutations (median 37.8% vs. 24.5%, p=0.015). No significant associations were observed between the percentage of Cyclin D1-positive TC and clinical outcomes. Conclusions Our data suggest that low expression of GLUT1 (HIF2-target) in TC may identify pts resistant to NKT2152 and are consistent with the hypothesis that tumors with low baseline levels of HIF2 activity are unlikely to respond to HIF2i. In preclinical models, VHL truncating mutations (causing complete loss of function) are known to lead to the highest HIF levels. As such, the observation that low expression of GLUT1 is inversely associated with VHL truncating mutations further supports GLUT1 expression as a surrogate marker of VHL/HIF2 pathway activation. Citation Format: Gabriel Roberti. de Oliveira, Berkay Simsek, Yasmin Laimon, Marc Machaalani, David McDermott, Jing Lu, Toni Choueiri, Sabina Signoretti. Baseline levels of HIF2 target proteins and response to the HIF2α inhibitor NKT2152 in patients with metastatic clear cell renal cell carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr A003.