Sipuleucel-T immunotherapy in clinical practice: Patient characteristics, tolerability, and survival.
e15211 Background: Sipuleucel-T has been shown to provide survival benefit to men with minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). In the 18 months following FDA approval of sipuleucel-T, we sought to characterize patients referred for consideration of sipuleucel-T, determine the tolerability of therapy, and evaluate survival outcomes in clinical practice. Methods: We reviewed the records of patients referred to our institution for consideration of sipuleucel-T. Clinical characteristics, disease characteristics, and previous treatments were identified. Tolerability and adverse events were characterized. Results: Patients with minimally symptomatic mCRPC were offered sipuleucel-T (n=90), whereas patients with ECOG>1, progressive disease, or lack of metastases were not (n=11). Post chemotherapy patients started sipuleucel-T if their CD4 count was >400 at least 3 weeks following chemotherapy. Treatments were well tolerated, with 96% completing an entire series. Three patients did not complete treatment due to disease progression. The biggest challenge with sipuleucel-T therapy was disease control immediately before, during and post therapy. Androgen receptor blockade with nilutamide or high dose bicalutamide was used to control the disease during this time. Mean patient age was 69.8±9.7 years and all had ECOG status of 0-1. 40% of patients had minimal metastases, while 36% and 19% had moderate or extensive metastases. Median survival time (MST) for men >65 years who received sipuleucel-T was 17.6 months, whereas MST for men ≤65 years was not reached. There was no significant difference in overall survival (OS) between these groups (p=0.27). When stratified by disease burden, we found that OS of patients with extensive disease was shorter than men with mild or moderate disease burden (p=0.002 and p=0.04), with MST of 6.0 months. MST was not reached for men with mild and moderate disease burden. Conclusions: Sipuleucel-T is well tolerated in clinical practice for well-selected patients with asymptomatic or minimally symptomatic mCRPC. Patients with extensive metastatic disease, even when minimally symptomatic, did not appear to benefit from sipuleucel-T.