Background: HD IL-2, an immunotherapy, is a standard of care for a select group of patients (pts) with mRCC. Generally objective response (OR) rates, i.e. complete response (CR) + partial response (PR), of 16-20% are discussed with pts, but not disease stabilization (SD). Recent data suggest that cancer immunotherapy may improve survival without inducing OR. Thus, treatment with HD IL-2 may provide survival benefit to an additional group of pts not experiencing OR, but only SD as the best response. Here we report CB ( OR+SD), and specifically report outcomes of cc mRCC pts experiencing SD as the best response, on treatment with HD IL-2. Methods: All sequential cc mRCC pts treated with HD IL-2 at the University of Utah Huntsman Cancer Institute from 2000-2012 were included. Pts were evaluated for best response, progression-free survival (PFS), time to next treatment (TNT) and overall survival (OS). Two practitioners independently reviewed HD IL-2 response with discrepancies adjudicated by a third reviewer. Results: 85 pts, 79% male, were identified with a median age of 56 (range 32-76) years. Pts belonged to the following MSKCC risk categories: 11 (13%) good, 70 (82%) intermediate, and 4 (5%) poor risk. A CR was identified in 9 (11%), PR in 5 (6%), SD in 26 (31%), progressive disease (PD) in 38 (45%), and unknown/not evaluable (NE) in 7 (8%) pts; yielding a clinical benefit in 40 (47%) pts. The median PFS, TNT, and OS in these individual groups of pts are compared in the table. Conclusions: A clinical benefit of HD IL-2 was achieved in nearly half of all clear cell mRCC pts. OS was not significantly different in OR and SD groups. Even though OR favorably determine outcomes, SD is also an important response criterion, and may be discussed during counseling pts for treatment with HD IL-2.

Abbreviation: NA, not achieved.