Interleukin-12 gene therapy prevents establishment of SCC VII squamous cell carcinomas, inhibits tumor growth, and elicits long-term antitumor immunity in syngeneic C3H mice

Interleukin-12 (IL-12) is an immunostimulatory agent with very promising antitumor activity. Using a retroviral expression vector, the authors have successfully transduced the genes encoding the two subunits of murine IL-12 to the squamous cell carcinoma cell line, SCC VII. Once IL-12 gene transcription and protein production were successfully verified, IL-12 expression was found to inhibit the establishment of SCC VII tumors in syngeneic C3H/HeJ mice inoculated with 1 x 10(6) SCC VII/IL-12 viable tumor cells. Mice immunized in this manner and rechallenged with parent SCC VII were capable of rejecting tumor up to 40% of the time. Treatment of established SCC VII tumors with irradiated IL-12-producing tumors cells led to significant tumor regression in a high percentage of animals.