Bispecific Chimeric Antigen Receptor Research Articles

1308 PROSTATE CANCER IMMUNOTHERAPY USING BI-SPECIFIC TUMOR-REACTIVE T CELLS

You have accessJournal of UrologyProstate Cancer: Basic Research II1 Apr 20121308 PROSTATE CANCER IMMUNOTHERAPY USING BI-SPECIFIC TUMOR-REACTIVE T CELLS Robert Chan, Ann Leen, Malcolm Brenner, Ganesh Palapattu, and Juan Vera Robert ChanRobert Chan Houston, TX More articles by this author , Ann LeenAnn Leen Houston, TX More articles by this author , Malcolm BrennerMalcolm Brenner Houston, TX More articles by this author , Ganesh PalapattuGanesh Palapattu Houston, TX More articles by this author , and Juan VeraJuan Vera Houston, TX More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.1655AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Novel therapeutic options for castrate-resistant prostate cancer (CRPC) are desperately needed. CRPC expresses tumor-associated antigens (TAAs), which are potential targets for immune destruction. Notably, tumors use multiple mechanisms of immune evasion including downregulation of TAAs. To overcome this hurdle, we generated bi-specific T cells to recognize two different TAAs simultaneously. METHODS We constructed a humanized and codon optimized first generation chimeric antigen receptor (CAR) targeting the tumor antigen Muc1, expressed in 90% of lymph node metastasis, which co-expressed truncated CD19 (selection marker to allow transgene detection) and prostate stem cell antigen (PSCA). We transduced primary human T cells and measured transgene expression. The cytolytic function of the transduced T cells was tested in an in vitro an 8 hr Cr51 release assay and a 96 hr co-culture experiment using the Muc1(+) and PSCA(+) prostate cancer cell line DU-145, as well as 293T cells modified to express either PSCA or Muc1, and 293T (negative control). In vivo studies using SCID mice subcutaneously injected with a mixture of 293T expressing PSCA and Muc1 were also performed. RESULTS CAR/Muc1 and CAR/PSCA transgene expression was 73.1 +/− 16.8% and 78.8 +/− 14.4%, respectively. In the Cr51 release assay, CAR/Muc1 T cells killed Du-145 (41.7 +/− 5.5% specific lysis at 20:1 effector:target ratio) unlike control T cells (8.2 +/− 2.2%). In addition, the killing was specific (i.e., 293T cells were not killed by transgenic T cells). These results were replicated in co-culture experiments and clearly showed that T cells with single target antigen specificity were unable to completely eliminate cancer burden- residual tumor cells did not express Muc1. Thus, additional CAR/PSCA T cells were generated which killed DU-145 (65.6 +/− 19.6% with no killing by control cells (8.2 +/− 2.2%). Finally to assess whether bi-specific T cells enhanced tumor recognition in vitro, we used a mixture of T cells expressing CAR/PSCA and CAR/Muc1 that showed enhanced killing in our in vitro models. In vivo, CAR/Muc-1 T cells reduced tumor size by 50% with further testing of CAR/PSCA and mixture in progress. CONCLUSIONS Our findings represent the first reported attempt to employ bi-specific CAR T cells to target prostate cancer. These promising data underscore the importance of multi-antigen targeting and provide strong rationale for similar approaches in men with CRPC. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e530 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Robert Chan Houston, TX More articles by this author Ann Leen Houston, TX More articles by this author Malcolm Brenner Houston, TX More articles by this author Ganesh Palapattu Houston, TX More articles by this author Juan Vera Houston, TX More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...