808P - Selecting Patients for High-Dose Interleukin-2 on the Basis of Tumour Histology

Abstract

ABSTRACT Background High-Dose Interleukin-2 (HD IL2) remains an option for treatment of metastatic renal cancer. In carefully selected patients, it can produce high rates of response with many durable remissions (Shablak A et al., J Immunotherapy 2011, 34(1):107–122). There remain uncertainties about the optimal way to select patients for treatment and here we update our approach to selecting patients for HD IL2 and include the analysis of carbonic anhydrase IX(CAIX) expression which has been previously suggested to correlate with response. Methods We present the outcomes of 103 patients with “favourable histology” (less than 10% papillary features and at least one of: >50% alveolar/solid (A/S) or >50% clear cell features) treated with first-line immunotherapy (including 19 who have failed prior targeted therapy) with HD-IL2. We examine the response rate in relation to histology and CAIX expression. Results Overall the response rate was 59/103 (57%) and the CR rate is 23/103 (22% - with 4 patients in PR and continuing treatment at the time of writing). Examination of the different features in relation to response suggested that the most important features were ≥ 50% A/S pattern as only 1/5 patients who had 50% A/S pattern and >80% CAIX staining the response rate was 22/37 (59%) and the CR rate was 9/37(24% with 4 patients in PR and continuing treatment at the time of writing). Conclusions These results extend and confirm our previously reported series (of 57 patients) and the overall response rate remains around 50% and that, combined with many durable complete remissions, results in an overall median survival 55 months (for all 103 patients) with an apparent plateau of 40% long term survivors. HD-IL2 remains an attractive option for carefully selected patients with metastatic clear cell renal cancer. The most tangible benefit of HD-IL2 is the ability to achieve durable complete remissions and our series suggests the optimal histological type in which to achieve this is patients whose tumour has Disclosure All authors have declared no conflicts of interest.