Immune responses and clinical outcomes in STAND, a randomized phase 2 study evaluating optimal sequencing of sipuleucel-T (sip-T) and androgen deprivation therapy (ADT) in biochemically-recurrent prostate cancer (BRPC) after local therapy failure.

5030 Background: STAND (NCT01431391) assessed optimal sequencing of sip-T and ADT in men with BRPC at high risk of metastases after local therapy (i.e. prostate specific antigen doubling time [PSADT] < 12 mo). Methods: Men (n = 68) were randomized to sip-T then ADT (2 wks post infusion 3; Arm 1) or ADT (3 mo lead-in) then sip-T (Arm 2). Cellular and humoral immune responses, and clinical outcomes were analyzed. PSA recurrence was defined as ≥ 2 serial rises in PSA and an absolute PSA value of ≥ 0.2 ng/mL (prior radical prostatectomy) or ≥ 2.0 ng/mL (prior radiotherapy alone). PSADT post-ADT was analyzed. Time to next anticancer intervention (TTACI) was measured from first ADT to the day of the next systemic therapy. Rate of metastases at 24 mo was also investigated. Results: All men received 3 sip-T doses, and 96% received 12 mo ADT. Cellular and humoral responses to PA2024 increased following treatment vs baseline (BL) and were sustained at all post-sip-T timepoints through 24 mo (p < 0.05). PA2024-speci...