Background: Trials of approved agents in mCRPC have reported shorter overall survival (OS) in men with visceral metastases (mets). The phase 3 IMPACT trial evaluated sipuleucel-T, an autologous cellular immunotherapy, in mCRPC but excluded visceral mets. PROCEED, a registry of mCRPC patients receiving sipuleucel-T, offers the first description of sipuleucel-T in patients with visceral mets. Methods: PROCEED enrolled men with mCRPC treated with sipuleucel-T biweekly x 3. Dose adjustment for organ dysfunction was unnecessary. Men were followed until death, study withdrawal, or a minimum of 3 years. OS is reported in this post-hoc subgroup analysis. Results: 1902 men received ≥1 sipuleucel-T infusion between 2011-2014. Visceral mets (n = 90) included liver (n=21), lung (n=61), and brain (n=2) involvement. Compared to patients without visceral mets (Table), men with visceral mets had poorer performance status (PS) and higher baseline prostate-specific antigen (PSA). Median OS was 20.5 and 31.2 mo in those with and without visceral mets. Patients with liver and lung mets had a median OS of 16.3 and 21.0 mo, respectively. Activation of antigen-presenting cells, a measure of immune activation and product potency, was similar in those with and without visceral mets. Conclusions: Initial observations suggest that patients with mCRPC and visceral spread can activate their immune cells to produce sipuleucel-T, but have a shorter OS than those with bone and/or lymph node spread. (NCT01306890). Clinical trial information: NCT00065442

APC = Antigen-presenting cell; CI = confidence interval; ECOG = Eastern Cooperative Oncology Group; ^aKaplan-Meier; ^bincluded 6 patients with liver and lung mets ^cincrease in surface CD54 on APCs expressed as an upregulation ratio of the average number of molecules on post vs pre-culture cells