Clinical features and response to immune combinations in patients with renal cell carcinoma and sarcomatoid de‐differentiation (ARON‐1 study)

Abstract Metastatic renal cell carcinoma (mRCC) carrying sarcomatoid features (sRCC) has aggressive biology and poor prognosis. First‐line immunotherapy (IO)‐based combinations have improved the outcome of clear cell RCC patients, including that of sRCC. Real‐world data confirming the adequate first‐line management of sRCC is largely lacking. We investigated the clinical features and the outcome of sRCC patients treated with IO‐based combinations within the ARON‐1 study population (NCT05287464). The primary objective was to define the incidence and baseline clinical characteristics of sRCC compared with non‐sRCC patients. The secondary objective was to describe the outcome of sRCC patients based on type of first‐line treatment (IO + IO vs. IO + tyrosin kinase inhibitor [TKI]). We identified 1362 mRCC patients with IMDC intermediate or poor risk, 226 sRCC and 1136 non‐sRCC. These two subgroups did not differ in terms of baseline characteristics. The median overall survival (OS) was 26.8 months (95%CI 21.6–44.2) in sRCC and 35.3 months (95%CI 30.2–40.4) in non‐sRCC patients ( p = .013). The median progression‐free survival (PFS) was longer in non‐sRCC patients compared to sRCC (14.5 vs. 12.3 months, p = .064). In patients treated with first‐line IO + TKI the median OS was 34.4 months compared to 26.4 months of those who received IO + IO ( p = .729). The median PFS was 12.4 months with IO + TKI and 12.3 months with IO + IO ( p = .606). In conclusion, we confirm that sRCC are aggressive tumors with poor prognosis. IO‐based combinations improve survival outcomes of sRCC patients, regardless from the type of strategy (IO + IO versus IO + TKI) adopted.