Immunotherapy counteracting the immuno-depressive effect of radio and chemotherapy

Surgery, radiotherapy and chemotherapy effect cures in a portion of cancer patients, but these treatments depress the immune system of the host. The purpose of our work was to find whether immunotherapy would abolish the depressive effect of the conventional treatment and thereby increase the percentage of cancer patients cured from their disease. The immunotherapeutic agent used was MER, a methanol extraction residue of the antituberculosis vaccine BCG. All patients had histologically proven neoplasia. The immunological responsiveness of the patients was evaluated before and after radiotherapy, chemotherapy and each MER treatment. The following immunological parameters were followed: (i) cutaneous delayed hypersensitivity to 3 recal antigens (PPD, SK-SD and Candidine); (ii) in vitro lymphocytic transformation to PHA and to the 3 above mentioned antigens. The patients were randomized into two groups. One group receiving injections of MER and the second acting as a control group. MER had no serious side effects and was well tolerated in most of the patients. The cutaneous reactivity became stronger and the lymphocytic stimulation index became higher after MER treatment. 51 patients with advanced lung cancer entered the trial. 29 were treated by MER after radiotherapy and/or chemotherapy and 22 control patients received only conventional therapy. There was no statistical significant difference in the survival between both groups, but it seems that in patients with locally advanced disease the survival was better in the MER group. MER treated group had less distant metastases which is in accord with the theory that immunotherapy is more effective in small tumours. Evidence points to the importance of the immune response in controlling the progression of malignant disease. Therefore, for neoplasia which cannot be controlled by surgery and/or radiotherapy and/or chemotherapy immunotherapy should be considered. (author)