PERILESIONAL INTERLEUKIN-2 IN THE VX-2 CARCINOMA IN RABBITS - A PRELIMINARY INVESTIGATION

Immune system amplification by perilesional injection of interleukin-2 is a promising adjuvant approach for treating squamous cell carcinoma of the head and neck. A pilot study was designed to develop an animal model bearing squamous cell carcinoma in which to test the efficacy o f perilesional interleukin-2. Rabbits were inoculated intramuscularly with the papilloma virus-induced squamous carcinoma VX-2 cell line. Tu mor regression and host lymphatic response after perilesional interleu kin-2 were measured. Variable responses were found. Growth of tumor ce lls implanted from cell culture was rapid in most animals. Tumor growt h was prevented in animals receiving 10,000 units of interleukin-2 per injection initiated 9 days after tumor inoculation. This inhibition a pproached statistical significance when compared with growth of saline controls. Histologic responses consisted primarily of plasma cell and eosinophil infiltration. The intensity of the inflammatory response d id not correlate with interleukin-2 dose. A trend toward enhanced tumo r growth was seen with lower doses of interleukin-2 and when interleuk in-a therapy was initiated simultaneously with tumor inoculation. Thes e findings suggest that high-dose recombinant interleukin-2 can preven t tumor growth if initiated after tumor inoculation. Whether this effe ct was caused by direct tumor cytotoxicity or mediated by the immune s ystem is unclear. These preliminary results underscore the importance of understanding the effects of dose and schedule in the design of imm unotherapy models before clinical use.