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Phase I/II clinical trials of dendritic cell-based immunotherapy in patients with the biochemical relapse of the prostate cancer.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: In order to have the highest impact on the control of tumor growth, cancer immunotherapy should be initiated as early in the disease course as possible. In prostate cancer, the effect of cancer immunotherapy at the minimal residual disease stage can be evaluated in patients with the biochemical relapse detected by ultrasensitive PSA measurements. We performed a Phase I/II clinical trial of dendritic cell based immunotherapy in patients with the biochemical relaps of the prostate cancer. Methods: Patients with the prostate cancer in the biochemical failure after radical prostatectomy or primary radiotherapy were enrolled in the study. Study medication consisted of 12 doses of 1x107 dendritic cells pulsed with killed prostate cancer cell line LNCap (DCVAC/PCa), injected s.c. in 4 weeks intervals. Primary goal of the study was to assess the safety. Secondary goals were PSA kinetics and presence of tumor antigen specific immune response in the peripheral blood. Study is registered as EudraCT 2009-017259-91. Results: Twenty patients were enrolled in the study and evaluated after receiving complete treatment cycle of DCVAC/PCa. Administration of DCVAC/PCa did not lead to any significant side effects. Continuous cancer immunotherapy by DCVAC/PCa significantly prolonged the PSA doubling time (PSA-DT) in all treated patients, on average there was a 3,43-fold increase of PSA-DT after the completion of the treatment. Seven of 20 patients had stable PSA levels during the treatment duration. Mean PSA-DT increased from 8,15 months before the initiation of cancer immunotherapy to 52,64 months at the completion of 12 doses, p<0.0015. Sustained T cells responses against PSA, NY-ESO1, MAGE A1 and MAGE A3 were detected in the peripheral blood of enrolled patients. Conclusions: This study indicates that the continuous cancer immunotherapy with dendritic cells loaded with killed LNCAP cell line represents efficient treatment modality for prostate cancer patients with biochemical relapse. This study supports the use of immunotherapy early in the course of the disease, provided that relevant surrogate endpoints predictive of improved prognosis of early stage patients will be identified. Clinical trial information: 2009-017259-91.