Abstract 5390: Anti-IL10-R1 monoclonal antibody with concomitant bacillus calmette-Guérin (BCG) prevents metastatic bladder cancer in an in vivo mouse model

Abstract

Introduction: Induction of Th1 immunity is required for effective intravesical BCG immunotherapy of bladder cancer. IL-10 down-regulates the Th1 response and is associated with BCG failure. We previously demonstrated that blocking IL-10 receptor (IL-10R) by systemic administration of anti-IL-10R1 mAb enhanced intravesical BCG (living Pasteur strain) treatment of bladder cancer in an orthotopic mouse model. Here we investigated the effect of anti-IL-10R1 mAb on clinically used BCG (lyophilized TICE strain) for induction of anti-bladder cancer immunity. Methods: Splenocytes were incubated with BCG alone or plus control IgG or ant-IL-10R1 mAb for 24 hours, followed by ELISA analysis of IFN-γ production. Bladder RNA was extracted after 6 treatments (twice weekly) with intravesical (i.b.) BCG plus intraperitoneal (i.p.) control IgG or anti-IL-10R1 mAb, followed by qPCR analysis of IFN-γ mRNA expression. Three groups of 20 mice were inoculated with luciferase-expressing MB49 bladder cancer cells and treated with i.b. PBS plus i.p. PBS (Group 1), i.b. BCG plus i.p. control IgG (Group 2), or i.b. BCG plus i.p. anti-IL-10R1 mAb (Group 3) 2x/wk for 6 total treatments. Mice were monitored weekly using IVIS luminescence and followed for 76 days. A bioluminesence cutoff of 5X104 p/s was used to establish the presence of bladder cancer. At animal death bladders were collected, weighed and processed for histological analysis. In suspected cases of metastatic disease the affected organs were also collected for histological analysis. Results: BCG plus anti-IL-10R1 mAb induced increased IFN-γ production by splenocytes in a dose-dependent manner. BCG plus anti-IL-10R1 mAb substantially increased IFN-γ mRNA. Eleven, 17 and 9 mice from Groups 1, 2 and 3, respectively, developed bladder cancer. One mouse in Group 2 and 2 mice in Group 3 showed cancer regression. 36%, 53% and 0% of Groups 1, 2 and 3 developed metastatic bladder cancer, respectively (p=0.020). While bladder weights for the groups were different, the differences did not reach statistical significance. Conclusions: Anti-IL-10R1 mAb enhances BCG-induced Th1 immune responses both in vitro and in vivo. Intravesical BCG plus anti-IL-10R1 mAb shows statistical significance in preventing metastasis of bladder cancer in an orthotopic bladder tumor mouse model. Anti-IL-10R1 mAb may prove useful in clinical practice for the prevention of metastatic bladder cancer in high-risk patients. 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 5390. doi:1538-7445.AM2012-5390