Biological response determinants in HSV-tk + ganciclovir gene therapy for prostate cancer

Mol Ther. 2006 Apr;13(4):716-28. doi: 10.1016/j.ymthe.2005.11.022. Epub 2006 Feb 15.


The limitations of current forms of prostate cancer therapy have driven researchers to search for new alternatives. Previously we showed cytopathic effect related to HSV-tk in prostate cancer. In this study we present initial results of a neoadjuvant HSV-tk gene therapy trial and address some of the potential mechanistic aspects of its effect in human tissues. We enrolled 23 men with clinically localized prostate cancer but high risk for recurrence in this Phase I-II trial. Intraprostatic viral injections (one to four) were followed by 2 weeks of ganciclovir and prostatectomy 2-4 weeks later. Toxicity was modest. Surgical specimens were embedded fully and whole-mount slides were imaged and analyzed for areas of cytopathic effect. The larger the tumor the greater the cytopathic effect. The effect also seems to be related to areas of high CAR expression. However, the number of injection sites did not influence effect. Local (CD8+ cells and macrophages) and systemic immune response (CD8+ and activated CD8+, IL-12) was increased in patients treated with HSV-tk. Increased apoptosis and decreased microvessel density were also noted in these patients. The results suggest a tumor-specific effect mediated by systemic and local immune response, antiangiogenic effect, and modulation of apoptosis.

Publication types

  • Clinical Trial, Phase I
  • Clinical Trial, Phase II
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Antiviral Agents / therapeutic use*
  • Apoptosis
  • Clinical Trials as Topic
  • Clinical Trials, Phase I as Topic
  • Clinical Trials, Phase II as Topic
  • Cytopathogenic Effect, Viral / drug effects
  • Follow-Up Studies
  • Ganciclovir / therapeutic use*
  • Genetic Therapy*
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Prostate-Specific Antigen / blood
  • Prostatectomy
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / surgery
  • Prostatic Neoplasms / therapy*
  • Simplexvirus / enzymology
  • Thymidine Kinase / genetics*
  • Time Factors
  • Treatment Outcome
  • Tumor Burden


  • Antiviral Agents
  • Thymidine Kinase
  • Prostate-Specific Antigen
  • Ganciclovir