Abstract 5379: Combination treatment with Bevacizumab, Lenalidomide, Docetaxel and Prednisone (ART-P) does not impact the immune response in patients with metastatic castration-resistant prostate cancer

Abstract

Abstract Purpose: Investigation of the effect of combination therapy for 5 cycles with bevacizumab, lenalidomide, docetaxel and prednisone (ART-P) on the immune response in patients with metastatic castration-resistant prostate cancer (mCRPC). The aim was to ascertain if treatment containing prednisone and docetaxel would impact immune responses, which could compromise the efficacy of subsequent immunotherapy. Experimental Design: We report here a study of immune responses in 12 patients enrolled in a phase II trial of ART-P at the National Cancer Institute (NCI). We compared peripheral blood mononuclear cells (PBMC) and serum samples collected at baseline and post 5 3-week cycles of ART-P treatment. PBMCs were analyzed using flow cytometry to characterize phenotypes of T-cells, regulatory T-cells, myeloid derived suppressor cells (MDSC) and natural killer (NK) cells, and T-cell proliferation as well as NK-cell functional activity were evaluated. Serum samples were analyzed for levels of cytokines, chemokines and vascular endothelial growth factor (VEGF) with ELISA assays. Results: The baseline characteristics for the 12 patients were: median age 65.7 years, Gleason score 8, and PSA 74 ng/ml. Greater than 50% decreases in PSA were seen in 9/12 patients, with a median decrease of 74%. Of the 12 patients 7 had a partial response, and 5 had stable disease by RECIST criteria. After 5 cycles of ART-P treatment we found no significant differences from baseline in T-cell proliferation and NK-cell function, or the frequencies of T-cells, regulatory T-cells, MDSC and NK-cells. There was also no change in the serum levels of cytokines and chemokines except for IL-6, which decreased. As expected, the serum levels of VEGF substantially decreased with therapy. Conclusions: Treatment of mCRPC patients with ART-P for 5 cycles did not alter the immune response in a way that would decrease the likelihood of successful immunotherapy, pre or post treatment with ART-P. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5379. doi:1538-7445.AM2012-5379