(ChemotherapyAdvisor) – Neoadjuvant sipuleucel-T increases T cell frequency in prostate cancer tissue at the rim between benign and malignant glands, a study to characterize the vaccine’s immune effects reported during the 2012 Genitourinary Cancers Symposium.

“These data suggest sipuleucel-T may modulate the presence of lymphocytes at the prostate tumor site,” Lawrence Fong, MD, University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, and co-investigators noted.

In the open-label Phase 2 study, 38 patients with localized prostate cancer received three infusions of sipuleucel-T at approximately two-week intervals beginning six to seven weeks prior to radical prostatectomy. Median patient age was 61 years; all had an ECOG performance status of 0. Prostate biopsies (pretreatment) and radical prostatectomy tissue (posttreatment) were assessed for lymphocytes by immunohistochemistry (IHC); to date, analysis has been completed in 19 patients.

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At the tumor rim, significant increases (>2-fold) in CD3+ and CD4+ T cell populations were observed vs. pretreatment biopsy; CD8+ T cells or CD56+ cells were not significantly increased compared with benign biopsy regions.

Operative complications, procedure time, and estimated blood loss did not appear to be affected by treatment with sipuleucel-T. Frequent adverse events that occurred ≤1 day after infusion were fatigue, headache, and myalgia, which were manageable and reversible. The investigators are continuing their work to characterize immune response within prostate tumor tissue and in the peripheral blood.

PROVENGE (sipuleucel-T), manufactured by Dendreon Corp., is FDA-approved as an autologous cellular immunotherapy for the treatment of asymptomatic or minimally symptomatic metastatic castrate resistant (hormone refractory) prostate cancer.

The 2012 Genitourinary Cancers Symposium is sponsored by the American Society of Clinical Oncology, American Society for Radiation Oncology, and the Society of Urologic Oncology.


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