Using genetically modified microvascular free flaps to deliver local cancer immunotherapy with minimal systemic toxicity.
BACKGROUND
Clinical use of cancer gene therapy has been prevented by the inability to deliver high levels of local transgene expression with acceptable host toxicity. The authors' laboratory has developed an ex vivo technique to genetically modify free flaps to deliver immunotherapy locally without systemic toxicity.


METHODS
Superficial inferior epigastric flaps were dissected in Fischer rats, perfused with a viral vector expressing the antitumor interleukin-12 (IL-12) for 1 hour, and re-anastomosed. Beneath the flaps was a bolus of 1 x 10(6) beta-human chorionic gonadotropin-secreting MADB-106 tumor cells. Tumor growth was monitored using beta-human chorionic gonadotropin levels (secreted by the tumor) and size. IL-12 expression in tissue was assessed by enzyme-linked immunosorbent assay. Tumor inflammatory infiltrate was assessed using immunohistologic staining (CD8 and CD161) and enzyme-linked immunosorbent assay (interferon-gamma). Serum levels of liver enzymes and histologic analysis were used to assess systemic toxicity.


RESULTS
IL-12 expression was confirmed in the flap and surrounding tissue. The rate of tumor growth in the IL-12-treated group was significantly suppressed compared with the control group (p < 0.001). Liver enzyme levels remained normal, and histological evaluation of the liver, lung, and spleen revealed no evidence of inflammation in the treated group.


CONCLUSIONS
Using genetically modified free flaps, the authors were able to deliver IL-12 directly into the local environment of a tumor and suppress its growth without eliciting toxic systemic effects. This technique could provide valuable adjuvant treatment after oncologic surgery for soft-tissue cancers, with the transduced flap reconstructing the defect and supplying a therapeutic agent to the resected tumor bed.
Dempsey
Marlese P
MP
Stanford, Calif. From the Department of Surgery, Division of Plastic Surgery, Stanford University School of Medicine.
Hamou
Cynthia
C
V
Joseph Michaels
JM
Ghali
Shadi
S
Jazayeri
Leila
L
Grogan
Raymon H
RH
Gurtner
Geoffrey C
GC
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology; D045744:Cell Line, Tumor; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000378:metabolism; D016503:Drug Delivery Systems; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007124:Immunoenzyme Techniques; D007167:Immunotherapy / Q000379:methods*; D018664:Interleukin-12 / Q000008:administration & dosage* / Q000235:genetics*; D007694:Killer Cells, Natural / Q000276:immunology / Q000473:pathology; D018655:Lymphocyte Count; D008297:Male; D008833:Microcirculation / Q000502:physiology; D009368:Neoplasm Transplantation / Q000276:immunology / Q000473:pathology; D009374:Neoplasms, Experimental / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D013524:Surgical Flaps / Q000098:blood supply*
D018997:Chorionic Gonadotropin, beta Subunit, Human; D018664:Interleukin-12