Papillary Renal Cell Carcinoma: Outcomes for Patients Receiving First-line Immune-based Combinations or Tyrosine Kinase Inhibitors from the ARON-1 Study

Background and objective: Papillary renal cell carcinoma (pRCC) is the most frequent histological subtype of non-clear cell RCC (nccRCC). Owing to the heterogeneity of nccRCC, patients are often excluded from large phase 3 trials focused on clear cell RCC, so treatment options for nccRCC remain limited. Our aim was to investigate the efficacy of first-line treatment with tyrosine kinase inhibitors (TKIs) or immuno-oncology (IO)-based combinations in patients with pRCC. Methods: We performed a multicenter retrospective analysis of real-world data collected for patients with advanced pRCC treated in 40 centers in 12 countries as part of the ARON-1 project (NCT05287464). The primary endpoints were overall survival (OS), progression-free survival (PFS), the overall response rate (ORR), and time to second progression (PFS2). OS, PFS, and PFS2 were estimated using the Kaplan-Meier method and results were compared between the treatment groups using a log-rank test. Univariate and multivariable analyses were carried out using Cox proportional-hazard models. Key findings and limitations: We included 200 patients with metastatic pRCC, of whom 73 were treated with IO-based combinations and 127 with TKIs. Median OS was 22.5 mo in the TKI group 28.8 mo in the IO group (p = 0.081). Median PFS was 6.4 mo in the TKI group and 17.4 mo in the IO group (p < 0.001). The ORR was higher in the IO group than in the TKI group (41% vs 27%; p = 0.037). Conclusions and clinical implications: Our results show that IO-based combinations have superior efficacy outcomes to TKIs for first-line treatment of metastatic pRCC. Patient summary: The ARON-1 project collects clinical data for patients with kidney cancer treated in multiple centers worldwide to assess outcomes in the real-world setting. We analyzed data for patients with metastatic kidney cancer of a specific subtype to evaluate the efficacy of different first-line treatments. Patients treated with immune-based combinations had better outcomes than patients treated with tyrosine kinase inhibitors.