Basic StudiesRadiotherapy Combined With Intratumoral Dendritic Cell Vaccination Enhances the Therapeutic Efficacy of Adoptive T-cell TransferTeitz-Tennenbaum, Seagal*; Li, Qiao*; Davis, Mary A.†; Wilder-Romans, Kari†; Hoff, Janet‡; Li, Mu*; Chang, Alfred E.* Author Information Departments of *Surgery †Radiation Oncology ‡Physiology, University of Michigan Medical Center, Ann Arbor, Michigan Financial Disclosure: All authors have declared there are no financial conflicts of interest in regards to this work. Reprints: Alfred E. Chang, Department of Surgery, University of Michigan, 1500 East Medical Center Drive, 3302 Cancer Center, Ann Arbor, MI 48109-0932 (e-mail: [email protected]). Received for publication January 14, 2009 accepted April 1, 2009 This work was supported by NIH grant CA59327, the Gillson Longenbaugh Foundation, and a gift from the Danto Family. Journal of Immunotherapy: July 2009 - Volume 32 - Issue 6 - p 602-612 doi: 10.1097/CJI.0b013e3181a95165 Buy Metrics Abstract Treatment of C57BL/6 mice with cyclophosphamide (100 mg/kg) and fludarabine (200 mg/kg) induced nonmyeloablative lymphodepletion without inhibiting D5 melanoma tumor growth. Using this model, we found that induction of lymphopenia before adoptive transfer of ex vivo anti-CD3/CD28 activated and interleukin-2 expanded D5-G6 tumor draining lymph node cells enhanced the antitumor efficacy of the infused cells in both pulmonary metastases and subcutaneous D5 bearing mice. However, induction of lymphopenia did not promote intratumoral or extratumoral proliferation or accumulation of the infused cells. We have previously shown that radiotherapy enhances the therapeutic efficacy of intratumoral unpulsed dendritic cell vaccination in subcutaneous murine tumor models by augmenting the induction of antitumor cellular immune responses. Here, we confirmed this finding in a murine metastatic melanoma liver tumor model. Furthermore, local tumor irradiation combined with intratumoral dendritic cell administration significantly enhanced the therapeutic efficacy of tumor-reactive T cell adoptive transfer in this lymphodepleted liver tumor model. This was evident by reduced liver tumor size, decreased incidence of spontaneous intra-abdominal metastasis, and prolonged survival, resulting in 46% of mice cured. This enhanced antitumor activity was associated with a selective increase in proliferation, accumulation, and function of CD4+ rather than CD8+ infused cells. This multimodality regimen may have translational applications for the treatment of human cancers. © 2009 Lippincott Williams & Wilkins, Inc.