#GU15 - Antigen-specific immune responses through 24 months in the STAND trial: A randomized phase 2 study evaluating optimal sequencing of sipuleucel-T and androgen deprivation therapy in biochemically-recurrent prostate cancer - Session Highlights

ORLANDO, FL, USA (UroToday.com) - Emmanuel S. Antonarakis from Johns Hopkins et al set out to measure antigenicitiy in the STAND trial which randomized sequence of treatment between sipuleucel-T and androgen deprivation therapy (ADT). Sixty-eight men with biochemical recurrence at high risk of metastasis were randomized to each arm, and cellular and humoral responses were measured through the first 2 years. Antigen-specific T-cell proliferation increased from baseline at all time points (p ≤ 0.001) but was lower in patients receiving ADT first (p < 0.001). gucancerssympaltAntigen-specific antibody titers were similar between treatment arms (p=0.976) and there was a clear induction of humoral immunity after the third sipuleucel dose, which remained present at 24 months in both arms. The number of immune responders (post-baseline antibody titer ≥ 1:25 600) was similar at any time point between arms with > 90% of patients in each arm. Higher nucleated cell count and baseline hemoglobin positively correlated with maximum antibody titer response (p < 0.05).

In summary, sipuleucel-T induced a robust immune response sustained to 24 months in men with BRPC, but cellular response appeared to differ according to treatment sequence. Humoral response was similar between treatment arms. Total nucleated cell count may be a potential biomarker of response to sipuluecel-T.

Presented by Emmanuel S. Antonarakis, MBBCh at the 2015 Genitourinary Cancers Symposium - "Integrating Biology Into Patient-Centric Care" - February 26 - 28, 2015 - Rosen Shingle Creek - Orlando, Florida USA

Johns Hopkins Medicine, Baltimore, MD USA

Reported by Phillip Abbosh, MD, PhD, medical writer for UroToday.com