Identification of biologic and inflammatory markers for predicting clinical responses to sipuleucel-T in CRPC.

134 Background: Sip-T prolongs OS in asymptomatic or minimally symptomatic CRPC. We prospectively evaluated biomarkers in men receiving Sip-T to identify predictors of SDP and OS. Methods: Circulating tumor cells (CTC), PSA, prostatic acid phosphatase (PAP), albumin (Alb), hemoglobin (Hb), serum alkaline phosphatase (SAP), LDH, C-reactive protein (CRP) and β2-microglobulin (β2m) were evaluated in a reference lab. SipT product parameters, CD54, CD54 upregulation (UPREG) and total nucleated cells (TNC) were measured by Dendreon. Survival was evaluated using Kaplan-Meier estimates; univariate Cox regression was used to investigate the effect of biomarkers on SDP and OS using 2-sided tests and corrected for multiple comparisons. Results: 92 men who received Sip-T were included. Median age was 69 (48-90). The median follow-up was 14 (1.3 –34.7) mos, and 33% of men had died. 21 men developed SDP at a median of 5.7 (1-19) mos. Univariate analyses of biomarkers and product parameters are shown in the table. In mu...