| Abstract: |
The genetic transfer of antigen receptors is a powerful approach to rapidly generate tumor-specific T lymphocytes. Unlike the physiologic T-cell receptor, chimeric antigen receptors (CARs) encompass immunoglobulin variable regions or receptor ligands as their antigen recognition moiety, thus permitting T cells to recognize tumor antigens in the absence of human leukocyte antigen expression. CARs encompassing the CD3Cζ chain as their activating domain induce T-cell proliferation in vitro, but limited survival. The requirements for genetically targeted T cells to function in vivo are less well understood. We have, therefore, established animal models to assess the therapeutic efficacy of human peripheral blood T lymphocytes targeted to prostate-specific membrane antigen (PSMA), an antigen expressed in prostate cancer cells and the neovasculature of various solid tumors. In vivo specificity and antitumor activity were assessed in mice bearing established prostate adenocarcinomas, using serum prostate-secreted antigen, magnetic resonance, computed tomography, and bioluminescence imaging to investigate the response to therapy. In three tumor models, orthotopic, s.c., and pulmonary, we show that PSMA-targeted T cells effectively eliminate prostate cancer. Tumor eradication was directly proportional to the in vivo effector-to-tumor cell ratio. Serial imaging further reveals that the T cells must survive for at least 1 week to induce durable remissions. The eradication of xenogeneic tumors in a murine environment shows that the adoptively transferred T cells do not absolutely require in vivo costimulation to function. These results thus provide a strong rationale for undertaking phase I clinical studies to assess PSMA-targeted T cells in patients with metastatic prostate cancer. ©2005 American Association for Cancer Research. |
| Keywords: |
unclassified drug; human cell; solid tumor; antigen expression; cell proliferation; t-lymphocytes; animals; mice; cell survival; lung neoplasms; membrane proteins; mice, scid; cell line, tumor; gene transfer; transduction, genetic; prostate cancer; prostatic neoplasms; t lymphocyte receptor; lymphocyte activation; prostate specific membrane antigen; immunoglobulin variable region; antigen specificity; receptors, antigen, t-cell; antigen recognition; chimeric antigen receptor; effector cell; target cell; tumor model; epitopes, t-lymphocyte; neovascularization (pathology); immunotherapy, adoptive; nih 3t3 cells; t lymphocyte activation; lymphocyte antigen receptor; immunologic memory; glutamate carboxypeptidase ii; antigens, surface; peripheral lymphocyte
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