The survival outcomes of the metastatic renal cell carcinoma with rhabdoid differentiation in immunotherapy era: Princess Margaret Cancer Center experience.

Abstract

333 Background: Patients (pts) diagnosed with metastatic renal cell carcinoma (mRCC) with rhabdoid differentiation (RD) have a poor prognosis due to aggressive tumor behavior and inherent treatment resistance to targeted therapies. However, recent data has demonstrated the survival benefit of immunotherapy (IO) in mRCC. Here, we report survival outcomes of pts with mRCC with RD treated with targeted therapy and or IO. Methods: This retrospective survival analysis was performed in pts with mRCC and RD treated with targeted treatment and IO at Princess Margaret Cancer Centre (PM), Toronto. Demographics, disease characteristics and survival outcomes were collected. Overall survival (OS) was calculated using the Kaplan-Meier method (log-rank). OS hazard ratio (HR) were calculated using cox proportional hazards model. IBM SPSS Statistics v26 was used to conduct statistical analyses. Results: We identified 474 pts diagnosed with mRCC at PM between 2002 and 2019. A total of 57 (12%) pts diagnosed with mRCC had RD and were treated with targeted and or IO agents. Of these, 42 (73.7%) pts had pure RD and 15 (26.3%) pts had mixed RD and sarcomatoid features. Median age was 62 yrs (35-86yrs) and 42 (73.7%) were male. Overall, as per the IMDC score, 5(8.8%), 27(47.4%) and 25(43.8%) pts were categorized as good, intermediate, and poor risk, respectively. In total, 34 (59.6%) pts were treated with targeted therapy only during their first and second line treatment course and 23 (40.4%) pts received IO alone or in combination with targeted treatment in the first or second line. With a median follow up of 53.4 months (range, 38.3-68.4 months), the median OS for the whole mRCC with RD cohort was 23.1 months (95% CI: 14.6-31.5). The median OS in all pts treated with targeted therapy only vs IO receipt was 13.1 months (95%CI: 5.4-20.8 months) vs not reached; p = 0.026, respectively. HR for OS was 0.44 (95%CI: 0.22-0.93; p = 0.03) favoring IO receipt. Conclusions: While the number of pts included in our retrospective review was small, our analysis has suggested that pts with mRCC and RD have poor survival outcomes that may be improved with IO treatment. RD is a histopathological feature that could identify pts who may benefit from IO therapy. Further analysis is needed to explore the impact of RD on IO treatment response.