Transfer of
tumor immunity as adjuvant
cancer therapy has been a topic of intense interest. We have examined the efficacy of various combinations of surgery, xenogeneic
immune RNA, xenogeneic normal
RNA,
tumor vaccine, and nonspecific splenocytes as adjuvant
therapy for
B16 melanoma in the C57BL/6J mouse system.
B16 melanoma was transplanted by
trocar into the right hind limb of 6-week-old mice. The
tumors were readily palpable on the ninth day posttransplantation. The
tumors were amputated at that time under mild
anesthesia.
Immune RNA was prepared by hot
phenol extraction from immune sheep spleens. Various combinations of
immune RNA, normal
RNA, and
tumor antigen, with or without normal mouse spleen cells, were administered every other day for a total of 10
injections. The survival and mode of death was followed up to 120 days. All mice without any treatment died within 30 days.
Immunotherapy had no effect on the survival of mice that did not have surgical
therapy. Individual group comparisons between mice that underwent surgery only and mice that had surgery plus
immune RNA immunotherapy revealed a striking statistical improvement (P less than 0.01). Comparing all groups that received
amputation plus various combinations of adjuvant
immunotherapy showed no statistical difference in survival. However,
immune RNA appears somewhat superior to normal
RNA or
antigen only. It appears that adjuvant
immune RNA immunotherapy following surgical excision in the
B16 melanoma model significantly improves survival and retards the spread of
metastases.