Initial experience with sipuleucel-T (sip-T) in the immediate post-approval setting: The University of Washington (UW) experience.

Abstract

e15206 Background: UW has participated in clinical trials of sip-T for over 15 years. After sip-T administration in the 3 phase III trials, patients (pts) did not receive additional therapy until objective progression. However, the course of treatment after administration of sip-T outside the setting of a clinical trial is not defined. In order to better understand our own practices in response to this new clinical scenario, we evaluated our institutional experience with commercial sip-T after FDA approval. Methods: Charts of all pts treated with sip-T at UW with at least 3 mos follow-up were retrospectively reviewed. Pt characteristics and treatments administered during the first 3 mos after sip-T infusion were collected. The institutional review board approved this study. Results: Between June 2010 and Nov 2011, 36 pts with mCRPC were treated with commercial sip-T by 3 different MDs. There were 31 Caucasian, 3 African American, and 2 Asian pts. At diagnosis, Gleason score (# pts) was 3+3 (2), 3+4 (5), 4+3 (7), 4+4 (4), 4+5 (16), 5+5 (2); initial therapy was watchful waiting (1), ADT with brachytherapy [BT] (1), BT with XRT (4), ADT/XRT (6), radical prostatectomy [RP] (9), ADT/RP (1). At the time of sip-T therapy, median age 67.8 yrs (44.2 to 84.5), median PSA 56.0, LDH 179.5, alk phos 77, Hgb 12.7, CTC 2. 3 pts had prior chemotherapy for metastatic disease. 34, 2, and 1 pts received 3, 2, and 1 sip-T infusion(s) respectively. Within the first 3 mos after the last sip-T dose, 29 pts had no significant symptoms and received no additional therapy other than ADT +/- ongoing zoledronic acid or denosumab (27), ketoconazole (1), or nilutamide (1); 7 developed pain and received docetaxel [D] (1), XRT and D (3), XRT (1), nilutatmide/D (1), or cabozantinib (1). 6 pts died a median of 10 months after sip-T; none had received chemotherapy before sip-T therapy. Conclusions: The majority of UW pts (80%) received no additional therapy in the first 3 mos after sip-T while 20% developed pain and were treated with docetaxel or other systemic therapy. What treatments should be given and at what interval after sip-T remains unclear. It is likely that new agents will impact the treatment paradigm after sip-T.