Results of randomized trials of immunotherapy for acute leukemia

Summary For more than a decade clinical trials have attempted to define the role of immunotherapy in the treatment of patients with acute leukemia. Based on animal studies which indicated that non-specific immune stimulation had an antitumor effect if the tumor burden was small, the use of immunotherapy during remission in patients with acute leukemia seemed appropriate following the initial report of the success of bacillus Calmette-Guerin (BCG) in prolonging remission duration and survival in acute lymphoblastic leukemia. Therefore a series of randomized clinical trials was initiated to confirm these original observations. In four studies comparing BCG inoculations, with or without allogeneic leukemia cells, and chemotherapy or no therapy, no advantage of immunotherapy was noted. Immunotherapy appeared to be equally as good as chemotherapy. A combination of BCG and chemotherapy showed some advantage in one study, but no advantage was noted in two other studies.In acute myeloblastic leukemia several randomized trials suggested that BCG or one of its derivatives when given alone, in combination with allogeneic cells, or with chemotherapy had a marginal effect in prolonging remission duration and survival when compared to chemotherapy or rno therapy.In conclusion, immunotherapy during remission has marginal activity in acute leukemia.