Background:Vaccine therapy in combination with radiation therapy may improve distant and/or local control in prostate cancer.
We present long-term follow-up data on the secondary and exploratory endpoints of safety and biochemical failure, respectively, from patients with clinically localized prostate cancer treated definitively with a poxviral vector-based therapeutic vaccine combined with external beam radiation therapy (EBRT).
Methods: Thirty-six prostate cancer patients received definitive EBRT plus vaccine. A total of 18 patients were treated with adjuvant standard-dose interleukin-2 (S-IL-2) (4 MIU m-2) and 18 were treated with very low-dose IL-2 (M-IL-2) (0.6 MIU m-2). Seven patients were treated with EBRT alone. Twenty-six patients treated with EBRT plus vaccine returned for follow-up, and we reviewed the most recent labs and clinical notes of the remaining patients.
Results: Median follow-up for the S-IL-2, M-IL-2 and EBRT-alone groups was 98, 76 and 79 months, respectively. Actuarial 5-year PSA failure-free probability was 78%, 82% and 86% (P=0.58 overall), respectively. There were no significant differences between the actuarial overall survival and the prostate cancer-specific survival between the two vaccine arms. Of the 26 patients who returned for follow-up, Radiation Therapy Oncology Group grade ≥2 genitourinary (GU) and gastrointestinal (GI) toxicity was seen in 19% and 8%, respectively, with no difference between the arms (P=1.00 and P=0.48 for grade ≥2 GU and GI toxicity, respectively). In all, 12 patients were evaluated for PSA-specific immune responses, and 1 demonstrated a response 66 months post-enrollment.
Conclusions: We demonstrate that vaccine combined with EBRT does not appear to have significant differences with regard to PSA control or late-term toxicity compared with standard treatment. We also found limited evidence of long-term immune response following vaccine therapy.
Written by:
Kamrava M, Kesarwala AH, Madan RA, Lita E, Kaushal A, Tsang KY, Poole DJ, Steinberg SM, Ferrara T, Dahut W, Schlom J, Gulley JL. Are you the author?
Department of Radiation Oncology, University of California at Los Angeles, Los Angeles, CA, USA.
Reference: Prostate Cancer Prostatic Dis. 2012 Mar 6. Epub ahead of print.
doi: 10.1038/pcan.2012.7
PubMed Abstract
PMID: 22391584
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