Immunotherapy of breast cancer, malignant melanoma, and acute leukemia with BCG: Prolongation of disease free interval and survival

Results of immunotherapy with BCG in patients with malignant melanoma, breast cancer, and acute leukemia are described. The first study demonstrated that high doses of living BCG organisms (6×10⁸ viable units) delivered by scarification in the upper arms and legs prolonged the disease-free interval and survival of 52 malignant melanoma patients with regional lymph node metastases compared to 218 comparable surgical control patients. Patients with trunk and extremity, but not head and neck melanoma, benefited from BCG, suggesting the importance of the delivery of BCG into the tumor-involved lymphatics. The second study evaluated the therapeutic efficacy of living BCG organisms by scarification in a group of adult acute leukemia patients after the cessation of chemotherapy. Thirty-seven patients had been in remission on intermittent chemotherapy for 12-24 months. Following late intensive consolidation chemotherapy, 7 consecutive patients received no further therapy and then 30 consecutive patients received BCG. Patients maintained on BCG have had a prolonged disease-free interval compared to those given on no further therapy (P=0.07) or compared to a group of similar patients maintained on chemotherapy alone (P=0.001). Similarly, the survival has been improved for patients maintained on BCG compared to those left unmaintained (P=0.009), or those maintained on chemotherapy (P=0.001). The principles of intermittent chemotherapy combined with BCG immunotherapy, first developed in patients with disseminated melanoma and acute myelogenous leukemia, have been confirmed in a series of patients with disseminated breast cancer. Forty-five patients treated with a combination of 5-FU, adriamycin, and cyclophosphamide (FAC) plus BCG by scarification showed prolongation of remission as well as survival compared to a comparable group of 44 patients treated with FAC chemotherapy without immunotherapy. Thus, 23/44 patients treated with FAC have died (median=14 months) compared to only 5/45 patients on FAC-BCG (median=12⁺ months), P=0.005. The limitations of BCG immunotherapy as well as speculations for future developments of immunotherapy are discussed.