Development of systemic immunologic responses against hepatic metastases during gene therapy for peritoneal carcinomatosis with retroviral HS-tk and ganciclovir.
Gene therapy with retroviral mediated gene transfer of the herpes simplex thymidine kinase (HS-tk) gene into a tumor mass confers sensitivity of the tumor cells to ganciclovir (GCV). Tumor-specific immunologic responses may develop following treatment of the primary tumor with retroviral HS-tk and GCV. In the present study we assessed whether GCV treatment of HS-tk transduced colon cancer (TK+) implanted in the peritoneal cavity induced a systemic antitumor response that would inhibit growth of a second wild-type (TK-) tumor implanted in the liver. DHDK12 rat colon cancer cells were transduced in vitro with the retroviral HS-tk vector and established as a permanent cell line (TK+ cells). TK+ or TK- DHDK12 cells (6x10(6) cells) were injected intraperitoneally on day 0 into BD-IX rats. On day 10, TK- cells (3x10(6) cells) were injected into the liver in all the groups. The animals were then treated with GCV (150 mg/kg) for 13 days. TK+ peritoneal tumors underwent significant regression during therapy with GCV (0.05+/-0.004 g; n=7) compared to wild-type (TK-) tumors (2.2+/-0.7g; n=6) (P<0.05). The volume of TK- tumors in the liver was significantly lower in GCV-treated rats with TK+ peritoneal tumors (12.5+/-8.3 mm3) compared to rats with TK- peritoneal tumors (96.7+/-18.1 mm3) (P<0.05). Histology of the liver tumors in the TK+ groups showed a dense monocytic infiltrate with fibrosis and only occasional viable tumor cells. Gene therapy with retroviral HS-tk vectors may provide a novel approach to treatment of gastrointestinal cancer by both direct cytotoxicity and an indirect mechanism that may include enhanced immuno logic responses against disseminated disease.
Misawa
T
T
Department of Surgery, University of Southern California School of Medicine, Los Angeles, CA 90033, USA.
Chiang
M H
MH
Pandit
L
L
Gordon
E M
EM
Anderson
W F
WF
Parekh
D
D
D000818:Animals; D002277:Carcinoma / Q000473:pathology* / Q000628:therapy*; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D015774:Ganciclovir / Q000627:therapeutic use*; D015316:Genetic Therapy / Q000379:methods*; D006561:Herpes Simplex / Q000201:enzymology* / Q000235:genetics*; D008113:Liver Neoplasms / Q000517:prevention & control* / Q000556:secondary*; D008297:Male; D010534:Peritoneal Neoplasms / Q000473:pathology* / Q000628:therapy*; D051381:Rats; D013937:Thymidine Kinase / Q000235:genetics*
D013937:Thymidine Kinase; D015774:Ganciclovir