Overall Survival and Immune Responses with Sipuleucel-T and Enzalutamide: STRIDE Study

Background: STRIDE (NCT01981122) is the first study comparing concurrent (con) vs sequential (seq) enzalutamide (enz) with sipuleucel-T (sip-T) in patients (pts) with metastatic castration-resistant prostate cancer. Pts were followed until death or for 3 years.

Methods: Fifty-two pts were randomized 1:1 to 3 sip-T infusions and enz started 2 wks before (n = 25, con) or 10 wks after (n = 27, seq) sip-T. Enz was continued for 52 wks or until disease progression (DP)/toxicity. Time to clinical outcomes was estimated by Kaplan-Meier analysis. 

Results: Median age (years): con 66; seq 72 (p = 0.01). Baseline characteristics and laboratory values were similar between arms. K-M estimated median follow up: 40.2 months. Clinical trial information: NCT01981122. 

Conclusions: Long-term follow-up suggests sip-T+enz is well-tolerated with no new safety concerns. Though not powered for such, con vs seq rx did not result in differences in OS or DP; differences in PSA responses cannot be excluded. Larger studies could better evaluate the clinical impact of combining immunotherapy with hormonal agents.

Screenshot 2018 11 05 20.31.16

NE, not estimable; PSA, prostate specific antigen *Clinically significant event or PSA progression Post-treatment (rx) antigen-specific cellular and humoral responses increased through wk 52 (p < 0.001). The seq arm resulted in greater magnitude of antibody titers; total response rates were similar between arms. Most common adverse events (AEs) were fatigue (50%), nausea (27%), back pain (19%), dizziness (19%), chills (17%). 15 pts developed grade 3–4 AE, 1 fatal (respiratory failure).

Daniel Peter Petrylak, Charles G. Drake, Christopher Michael Pieczonka, John M. Corman, Jorge A. Garcia, Curtis Dunshee, Tim Van Mouwerik, Robert C. Tyler, Nancy N. Chang, and David Quin

Smilow Cancer Center at Yale University, New Haven, CT; Columbia University Herbert Irving Comprehensive Cancer Center, New York, NY; Associated Medical Professionals of New York, PLLC, Syracuse, NY; Virginia Mason Medical Center, Seattle, WA; Cleveland Clinic Taussig Cancer Institute, Cleveland, OH; Urological Associates of Southern Arizona P.C., Tucson, AZ; Dendreon Pharmaceuticals, Inc., Seattle, WA; USC Keck School of Medicine Norris Comprehensive Cancer Center, Los Angeles, CA; Smilow Cancer Center at Yale University, New Haven, CT; Columbia University Herbert Irving Comprehensive Cancer Center, New York, NY; Associated Medical Professionals of New York, PLLC, Syracuse, NY; Virginia Mason Medical Center, Seattle, WA; Cleveland Clinic Taussig Cancer Institute, Cleveland, OH; Urological Associates of Southern Arizona P.C., Tucson, AZ; Dendreon Pharmaceuticals, Inc., Seattle, WA; USC Keck School of Medicine Norris Comprehensive Cancer Center, Los Angeles, CA

DOI: 10.1200/JCO.2018.36.6_suppl.246 Journal of Clinical Oncology 36, no. 6_suppl (February 2018) 246-246.
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