Extension of overall survival beyond objective responses in patients with metastatic renal cell carcinoma treated with high-dose interleukin-2

Purpose In metastatic renal cell carcinoma (mRCC), survival benefit associated with objective response rates of 16–20 % with high-dose interleukin-2 (HDIL-2) is well established and discussed. Based on recently emerged data on efficacy of cancer immunotherapy, we hypothesized that the survival benefit with HDIL-2 extends beyond those achieving objective responses, i.e., to those who achieve stable disease as the best response to treatment. Materials and methods All sequential treatment naïve mRCC patients treated with HDIL-2 at the University of Utah (1988–2013) and University of Michigan (1997–2013) were included. Best responses on treatment were associated with survival outcomes using log-rank and COX regression with a landmark analysis at 2 months. Results 391 patients (75 % male; median age 55 years) were included and belonged to the following prognostic risk categories: 20 % good, 64 % intermediate, and 15 % poor. Best responses on treatment were complete response (9 %), partial response (10 %), stable disease (32 %), progressive disease (42 %), and not evaluable for response (7 %). No significant differences in progression-free survival (HR 0.74, 95 % CI 0.48–1.1, p = 0.14) or overall survival (HR 0.66, 95 % CI 0.39–1.09, p = 0.11) were observed between patients achieving partial response versus stable disease. Significant differences in progression-free survival (HR 0.13, 95 % CI 0.09–0.22, p < 0.0001) and overall survival (HR 0.33, 95 % CI 0.23–0.48, p < 0.0001) were observed between patients achieving stable disease compared to those with progressive disease and who were not evaluable. Conclusions Survival benefit with HDIL-2 is achieved in ~50 % patients and extends beyond those achieving objective responses.