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Immune response from STRIDE, a randomized, Phase II, open-label study of sipuleucel-T (sip-T) with concurrent vs sequential enzalutamide (enz) administration in metastatic castration-resistant prostate cancer (mCRPC)
  1. Charles G Drake1,
  2. David Quinn2,
  3. Robert Dreicer3,
  4. Emmanuel Antonarakis4,
  5. Neal Shore5,
  6. John Corman6,
  7. Raoul Concepcion7,
  8. Christopher Pieczonka8,
  9. Dwayne Campogan9,
  10. Li-Qun Fan9,
  11. Nancy Chang9,
  12. Nadeem Sheikh9 and
  13. Daniel Petrylak10
  1. Aff1 grid.21107.350000000121719311Department of OncologySidney Kimmel Comprehensive Cancer Center at Johns Hopkins University Baltimore MD USA
  2. Aff2 grid.42505.360000000121566853Norris Comprehensive Cancer CenterUniversity of Southern California Los Angeles CA USA
  3. Aff3 grid.27755.32000000009136933XUniversity of Virginia Cancer Center Charlottesville VA USA
  4. Aff4 grid.21107.350000000121719311Johns Hopkins University School of Medicine Baltimore MD USA
  5. Aff5 Atlantic Urology Clinics Myrtle Beach SC USA
  6. Aff6 grid.416879.50000 0001 2219 0587Virginia Mason Cancer Institute Seattle WA USA
  7. Aff7 grid.417627.1Urology Associates Nashville TN USA
  8. Aff8 Associated Medical Professionals of New York Syracuse NY USA
  9. Aff9 grid.421886.10000 0004 0463 3147Dendreon Seattle WA USA
  10. Aff10 grid.433818.5Yale Cancer Center New Haven CT USA

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Meeting abstracts


P12-2 (STRIDE; NCT01981122) is an ongoing, randomized, Phase II, open-label study evaluating concurrent vs sequential administration of the androgen receptor inhibitor, enz, with the autologous cellular immunotherapy, sip-T. The primary aim of this study is to determine if the order of sip-T and enz administration impacts immune responses to the immunizing antigen, PA2024, of sip-T.


Patients with asymptomatic or minimally symptomatic mCRPC were randomized 1:1 to receive 3 sip-T infusions with enz starting 2 weeks (wks) before (n=25, concurrent arm A) or 10 wks after (n=27, sequential arm B) sip-T initiation. Antigen-specific cellular and humoral immune responses were evaluated via interferon (IFN)-γ ELISPOT, cell proliferation, and antibody ELISA assays. In addition, the breadth of the humoral response to non-target antigens was also studied.


T cell proliferative responses to PA2024 were significantly elevated at all post-baseline time points (p < 0.001) and were sustained through wk 26, including a >10-fold increase at wk 20 in both arms. Both arms showed a significant and sustained increase in IFN-γ ELISPOT response to PA2024 and humoral responses to PA2024 and PAP. Broadening of the humoral responses to non-target antigens PSA, LGALS3, LGALS8, KRAS, ERAS and KLK2 at all post-treatment time points was observed in both arms. Cytokines indicative of immune activation (including IFN-γ, interleukin-2, and tumor necrosis factor-α) were also elevated in both arms, at the 2nd and 3rd sip-T infusions. Adverse events were similar between arms.


Treatment of mCRPC subjects with enz administered concurrently with or subsequent to sip-T resulted in significant and sustained peripheral antigen-specific T cell and humoral immune responses through wk 26. Both treatment schedules led to similarly robust humoral antigen spread sustained through wk 26. These data suggest enz did not affect sip-T production, subsequent immune responses, or safety.

Trial registration identifier NCT01981122.