CLINICAL OUTCOME OF PATIENTS WITH NON-CLEAR METASTATIC RENAL CELL CARCINOMA TREATED WITH PEMBROLIZUMAB-AXITINIB COMBINATION. NEMESIA (NON CLEAR METASTATIC RENAL CELL CARCINOMA PEMBROLIZUMAB AXITINIB) STUDY, A SUBGROUP ANALYSIS OF I-RARE OBSERVATIONAL STUDY (MEET-URO 23A)

Background: Non-clear cell renal cell carcinoma (nccRCC) represents a heterogeneous histological group which amount 20-25% of RCC. nccRCC have limited therapeutic options due to their exclusion from phase III randomized trials. Therefore, the aim of this study was to investigate the efficacy of pembrolizumab- axitinib in chromophobe and papillary metastatic RCC patients enrolled in the I-RARE observational ongoing study (Meet-URO 23). Methods: Baseline characteristics, outcome data including progression-free survival (PFS) and toxicities were retrospectively collected from nccRCC pts treated in 12 Italian referral centers adhering to the Meet-Uro group, from December 2020 to April 2022. Only patients with cromophobe and papillary histology were considered eligible. Results: 25 eligible patients received pembrolizumab-axitinib as first-line treatment. 11/25 (44%) patients had cromophobe histology whereas 14/25 (56%) were classified as papillary RCC. Characteristic of patients are reported in table 1. The disease control rate was 86.3% (10/25 patients achieved stable disease and 9/25 patients obtained partial response: 5/9 papillary, 4/9 chromophobe). 2/25 (8%) patients were primary refractory. Median PFS was 10.8 months (95%CI 1.7-11.5). 7/25 (28%) patients interrupted the full treatment due to immune-related adverse events (irAEs) (G3 hepatitis (n=4), G3 hypophisitis (n=1), G2 pneumonia (n=1), G3 pancreatitis (n=1), whereas 2/25 (8%) patients interrupted axitinib only due to persistent G2 hand-foot syndrome or G2 hypertension. Conclusions: Pembrolizumab- axitinib could be an active option in papillary and cromophobe RCC.