A POTENTIAL APPROACH TO IMMUNOTHERAPY OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL): ENHANCED IMMUNOGENICITY OF CLL CELLS VIA INFECTION WITH VECTORS ENCODING FOR MULTIPLE COSTIMULATORY MOLECULES. Chronic lymphocytic leukemia (CLL) is a disease of CD5+ B lymphocytes (designated as CLL cells) that are inefficient antigen-presenting cells. Their poor ability to present antigens to the T cells, largely due to an inadequate costimulatory capacity, is manifested as a failure to stimulate proliferation of both allogeneic and autologous T cells. We have investigated the ability of in vitro manipulated CLL cells, via hyperexpression of a triad of costimulatory molecules (B7-1, ICAM-1 and LFA-3, designated TRICOM), to stimulate effective anti-tumor T-cell responses. A recombinant Modified Vaccinia Virus strain Ankara (MVA), which is a highly attenuated, replication-impaired virus variant, was successfully used to infect and deliver the simultaneous expression of the 3 human costimulatory molecules in TRICOM on the surface of the CLL cells. Proliferation of allogeneic and autologous T cells was observed when MVA-TRICOM infected CLL cells were used as stimulators in proliferation assays. Cytotoxic T lymphocytes, generated in vitro by stimulation of autologous T cells with MVA-TRICOM-infected CLL cells, showed cytotoxicity against unmodified/uninfected CLL cells. Therefore, our findings suggest that the use of CLL cells infected ex vivo with MVA-TRICOM or direct injection of MVA-TRICOM in CLL patients has potential for the immunotherapy of CLL.PHASE I STUDY OF SEQUENTIAL VACCINATIONS WITH FOWLPOX-CEA(6D)-TRICOM ALONE AND SEQUENTIALLY WITH VACCINIA-CEA(6D)-TRICOM, WITH AND WITHOUT GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR, IN PATIENTS WITH CARCINOEMBRYONIC ANTIGEN-EXPRESSING CARCINOMAS. Previous clinical experience with vaccinia and replication-defective avipox recombinant carcinoembryonic antigen (CEA) vaccines has demonstrated safety and clinical activity with a correlation between CEA-specific immune response and survival. Preclinical evidence demonstrated that the addition of the transgenes for three T-cell costimulatory molecules (B7-1, ICAM-1, LFA-3, designated TRICOM) results in a significant improvement in antigen-specific T-cell responses and antitumor activity. We have completed the first trial in humans of the CEA-TRICOM vaccines (also including an enhancer agonist epitope within the CEA gene). Fifty-eight patients with advanced CEA-expressing cancers were accrued to eight cohorts that involved vaccinations with the following: replication-defective fowlpox recombinant (rF)-CEA(6D)-TRICOM; primary vaccination with recombinant vaccinia (rV)-CEA(6D)-TRICOM plus rF-CEA(6D)-TRICOM booster vaccinations; and rV-CEA(6D)-TRICOM and then rF-CEA(6D)-TRICOM, plus granulocyte-macrophage colony-stimulating factor (GM-CSF) with vaccines, or with divided doses of vaccine with GM-CSF. Vaccines were administered every 28 days for six doses and then once every 3 months. Reverting to treatments every 28 days was allowed if patients progressed on the 3-month schedule. In this phase I study, no significant toxicity was observed. Twenty-three patients (40%) had stable disease for at least 4 months, with 14 of these patients having prolonged stable disease (> 6 months). Eleven patients had decreasing or stable serum CEA, and one patient had a pathologic complete response. Enhanced CEA-specific T-cell responses were observed in the majority of patients tested. We demonstrated that the CEA-TRICOM vaccines are safe and can generate significant CEA-specific immune responses, and they seem to have clinical benefit in some patients with advanced cancer.COMBINING A RECOMBINANT CANCER VACCINE WITH STANDARD DEFINITIVE RADIOTHERAPY IN PATIENTS WITH LOCALIZED PROSTATE CANCER. Many patients with clinically localized prostate cancer develop biochemical failure despite excellent local therapy perhaps due to occult metastatic disease.
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