A national multicenter phase 2 study of prostate-specific antigen (PSA) pox virus vaccine with sequential androgen ablation therapy in patients with PSA progression: ECOG 9802

Eur Urol. 2015 Sep;68(3):365-71. doi: 10.1016/j.eururo.2014.12.010. Epub 2014 Dec 18.

Abstract

Background: E9802 was a phase 2 multi-institution study conducted to evaluate the safety and effectiveness of vaccinia and fowlpox prostate-specific antigen (PSA) vaccine (step 1) followed by combination with androgen ablation therapy (step 2) in patients with PSA progression without visible metastasis.

Objective: To test the hypothesis that vaccine therapy in this early disease setting will be safe and have a biochemical effect that would support future studies of immunotherapy in patients with minimal disease burden.

Design, setting, and participants: Patients who had PSA progression following local therapy were treated with PROSTVAC-V (vaccinia)/TRICOM on cycle 1 followed by PROSTVAC-F (fowlpox)/TRICOM for subsequent cycles in combination with granulocyte-macrophage colony-stimulating factor (step 1). Androgen ablation was added on progression (step 2).

Outcome measurements and statistical analysis: Step 1 primary end points included progression at 6 mo and characterization of change in PSA velocity pretreatment to post-treatment. Step 2 end points included PSA response with combined vaccine and androgen ablation.

Results and limitations: In step 1, 25 of 40 eligible patients (63%) were progression free at 6 mo after registration (90% confidence interval [CI], 48-75). The median pretreatment PSA velocity was 0.13 log(PSA)/mo, in contrast to median postregistration velocity of 0.09 log(PSA)/mo (p=0.02), which is an increase in median PSA doubling time from 5.3 mo to 7.7 mo. No grade ≥4 treatment-related toxicity was observed. In the 27 patients eligible and treated for step 2, 20 patients achieved a complete response (CR) at 7 mo (CR rate: 74%; 90% CI, 57-87). Although supportive of larger studies in the cooperative group setting, this study is limited by the small number of patients and the absence of a control group as in a phase 3 study.

Conclusions: A viral PSA vaccine can be administered safely in the multi-institutional cooperative group setting to patients with minimal disease volume alone and combined with androgen ablation, supporting the feasibility of future phase 3 studies in this population.

Patient summary: These data support consideration of vaccine therapy earlier in the course of prostate cancer progression with minimal disease burden in future studies of vaccine approaches in earlier stages of disease.

Keywords: PSA; Pox virus; Prostate cancer; Vaccine.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Androgen Antagonists / therapeutic use*
  • Cancer Vaccines / immunology
  • Cancer Vaccines / therapeutic use*
  • Combined Modality Therapy
  • Disease Progression
  • Fowlpox virus / immunology
  • Granulocyte-Macrophage Colony-Stimulating Factor / therapeutic use
  • Humans
  • Kallikreins / blood
  • Kallikreins / immunology*
  • Male
  • Middle Aged
  • Prostate-Specific Antigen / blood
  • Prostate-Specific Antigen / immunology*
  • Prostatectomy
  • Prostatic Neoplasms / drug therapy*
  • Vaccinia virus / immunology

Substances

  • Androgen Antagonists
  • Cancer Vaccines
  • PROSTVAC
  • Granulocyte-Macrophage Colony-Stimulating Factor
  • Kallikreins
  • kallikrein-related peptidase 3, human
  • Prostate-Specific Antigen