Active specific immunization in malignant melanoma

The effects of active specific immunization with nonirradiated autologous and irradiated cultured allogeneic melanoma tumor cells (TC) on cell‐associated immunity was studied in 11 patients with widespread malignant melanoma receiving chemoimmunotherapy. Immunization with 1 × 10⁶‐8 × 10⁷ TC was done in the draining area of a BCG scarification on day 7 of the study. The in vitro lymphocyte blastogenic response (BR) to autologous TC was studied in terms of the stimulation index on day 1, 7, 14, and 21. The stimulation index (SI) was the counts per min (cpm) in the TC stimulated culture minus the cpm among the TC alone divided by the cpm in the unstimulated controls. A positive BR was considered as a SI equal to or greater than 3. Six out of 11 patients had a significant increase in BR lasting 7‐14 days after immunization. The pre‐ to post‐immunization changes in the SI of the 6 patients were 2.5 to 7.5; 0.7 to 3.2; 0 to 5.2; 0 to 16; 0.1 to 6.6; and 6.5 to 30.0. Nine out of 11 patients showed a delayed local inflammatory reaction at the immunization site. Five out of 11 patients mounted a cutaneous delayed hyper sensitivity reaction to autologous tumor cells at a separate test site following immunization. There were no side effects. Active specific immunization in the drainage of a BCG reaction appears to be safe. Since a positive BR to autologous TC correlates with a good prognosis in patients with solid tumors, studies of the immunotherapeutic efficacy of this approach may be warranted.