465 Background: Chromophobe RCC represents a rare subtype of kidney cancer, which very infrequently metastasizes. Once metastatic, prognosis is poor. Preferred Rx include clinical trial enrollment, VEGF-targeted therapies (TKI) alone or in combination with programmed cell death protein-1 (PD-1) inhibitor (NCCN Guidelines V1.2026). Given the lack of standardized treatment approach, we sought to characterize Rx patterns and survival outcomes of patients (pts) with mchRCC in a real-world setting. Methods: Using the US-based electronic health record-derived deidentified Flatiron Health Research Database, pts diagnosed with metastatic RCC with chromophobe histology and evidence of receiving approved first line (1L) Rx were eligible. Rx patterns up to 5L, real-world time to next treatment (rwTTNT), and real world overall survival (rwOS) by line (L) of therapy were analyzed. Results: Overall 155 pts with mchRCC diagnosed from 1/18/2011 to 10/31/2024 were eligible and included in the analysis. Median age was 65 years (IQR 57, 73), 101 pts (65.2%) were non-Hispanic White and 107 pts (69%) were male. TKIs were the most common 1L regimen (71; 45.8%), followed by PD-1 inhibitor + TKI (18; 11.6%), and PD-1 inhibitor + CTLA-4 inhibitor (17; 11.0%). In 2L, TKI (37; 34.3%) and single-agent PD-1 inhibitors (19; 17.6%) were the most common Rx. By 3L, Rx was more heterogeneous, with TKIs (17; 27.9%), single PD-1 inhibitor (15; 24.6%), and everolimus (7; 11.5%) representing the main Rx. Among 1L-treated pts, median OS was 30 months for TKIs, not reached for PD-1 inhibitor + TKI, and 21 months for PD-1 inhibitor + CTLA-4 inhibitor. Further characterization of Rx patterns by line of Rx and survival outcomes will be provided at the meeting. Conclusions: In this largest series of mchRCC to our knowledge, survival outcomes varied across regimens. The substantial heterogeneity in Rx patterns and outcomes underscores the lack of a clear optimal sequencing of therapies and highlights the urgent need for randomized trials to define optimal Rx sequencing in this setting.
Hardy et al. (2026) studied this question.