Adjuvant Atezolizumab in Patients with Sarcomatoid Renal Cell Carcinoma: A Prespecified Subgroup Analysis of IMmotion010.

Patients with sarcomatoid renal cell carcinoma (sRCC) have a poor prognosis. In the randomised, double-blind phase 3 IMmotion010 trial (NCT03024996), adjuvant atezolizumab did not demonstrate a disease-free survival (DFS) benefit versus placebo in the overall population of patients with locoregional renal cell carcinoma with an increased risk of recurrence following surgery. This prespecified subgroup analysis of efficacy and safety was completed in 104 patients with sRCC. Baseline characteristics were similar between treatment arms. At a median follow-up of 45 mo, the median DFS was not evaluable (NE; 95% confidence interval [CI], 12 mo-NE) in the atezolizumab arm (n = 37) and 23 mo (95% CI, 11-NE) in the placebo arm (n = 66; hazard ratio 0.77 [95% CI, 0.44-1.4]). In the sRCC subgroup, grade 3/4 treatment-related adverse events (TRAEs) occurred in one patient (2.7%) in the atezolizumab arm and two patients (3.0%) in the placebo arm. By comparison, 54 of 353 patients (15%) and 16 of 317 patients (5.0%) with non-sarcomatoid histology reported grade 3/4 TRAEs in the respective arms. In conclusion, the difference in DFS was not statistically significant between adjuvant atezolizumab and placebo in patients with sRCC. The safety profile was similar between patients with sRCC and non-sRCC. PATIENT SUMMARY: Patients with a specific type of locoregional kidney cancer (tumours with sarcomatoid features) were treated with atezolizumab or placebo after surgery. Slightly more patients treated with atezolizumab lived longer without the disease getting worse than those treated with placebo, although this finding was not statistically significant. The side effects were similar to those seen in patients with other types of kidney cancer treated with atezolizumab in the same study (IMmotion010). In patients with sarcomatoid kidney cancer, atezolizumab was tolerable and may be more effective than placebo, but this requires further study.