Outcomes of metastatic chromophobe renal cell carcinoma (ChRCC) with sarcomatoid features (SF).

Abstract

678 Background: ChRCC makes up 5-10% of RCC subtypes and is generally thought to confer favorable prognosis. Presence of SF on histologic review can occur in any RCC subtype and is considered a hallmark of aggressive disease. We assessed outcomes in a cohort of patients (pts) with metastatic ChRCC and SF (sChRCC). Methods: Baseline clinical features and details on treatment were collected for pts with newly diagnosed metastatic sChRCC evaluated at Memorial Sloan Kettering Cancer Center (MSKCC) between 2002-17. Overall survival (OS) was calculated for all patients and time to treatment failure (TTF) for those who received first-line therapy at MSKCC. Next generation sequencing (NGS) with MSK-IMPACT was performed in a subset of pts. Results: 27 pts with newly diagnosed metastatic sChRCC were identified; other clinical features are summarized below ( table). 2 pts never received first line therapy based on poor performance status. 16 were treated at MSKCC and received a median of 2 lines of systemic therapy. First line agents included sunitinib (n = 6), pazopanib (n = 2), temsirolimus (n = 2), everolimus + bevacizumab (n = 2), sunitinib + gemcitabine (n = 2) and interferon alpha (n = 2) with median TTF of 2.1 months (0.9-14.5). Across the entire cohort (n = 27), median OS was 7.9 months (95% CI 4.2-11.2) with estimated 1 year OS rate of 25%. By comparison, a cohort of 67 pts with metastatic ChRCC lacking SF also treated at MSKCC 2002-17 achieved median OS of 38.1 months, (HR 4.6; 95% CI: 2.6-8.3; p < 0.001). In the 6 sChRCC pts with NGS analysis, TP53 (n = 4), PTEN (n = 2) and CHEK2 (n = 2) were the most frequently altered genes. Conclusions: Outcome for pts with metastatic sChRCC was poor in contrast to pts with ChRCC lacking SF. The lack of benefit observed across various classes of systemic agents warrants study of underlying biology and novel agents. [Table: see text]