Biological response determinants in HSV-tk + ganciclovir gene therapy for prostate cancer.
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.
Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. gayala@bcm.tmc.edu
Gustavo
G
Ayala
Takefumi
T
Satoh
Rile
R
Li
Moshe
M
Shalev
Yehoshua
Y
Gdor
Estuardo
E
Aguilar-Cordova
Anna
A
Frolov
Thomas M
TM
Wheeler
Brian J
BJ
Miles
Kate
K
Rauen
Bin S
BS
Teh
E Brian
EB
Butler
Timothy C
TC
Thompson
Dov
D
Kadmon
D000368:Aged; D000998:Antiviral Agents / Q000627:therapeutic use*; D017209:Apoptosis; D002986:Clinical Trials as Topic; D017321:Clinical Trials, Phase I as Topic; D017322:Clinical Trials, Phase II as Topic; D003588:Cytopathogenic Effect, Viral / Q000187:drug effects; D005500:Follow-Up Studies; D015774:Ganciclovir / Q000627:therapeutic use*; D015316:Genetic Therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D018139:Simplexvirus / Q000201:enzymology; D013937:Thymidine Kinase / Q000235:genetics*; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden
D000998:Antiviral Agents; D013937:Thymidine Kinase; D017430:Prostate-Specific Antigen; D015774:Ganciclovir