Immunotherapy in the Management of Leukaemia

Abstract

Summary.Now that it has been clearly established that tumour associated antigens exist in acute leukaemia in man, as in animals, the possibility of stimulating the patient's immune system to react against them arises. In animal experiments the most effective method of influencing the progress of leukaemias and lymphomas after the implantation of living malignant cells has been a combination of nonspecific stimulation of the reticulo‐endothelial system, with agents such as BCG or Corynebacterium parvum, either with chemotherapy or with specific immunization with irradiated leukaemic cells. However, such treatment is only effective if the number of living malignant cells is small as it takes a powerful immune response to overcome even a small number of malignant cells. It is for these reasons that most of the studies in man have been on patients with acute leukaemia in remission. Mathé, in 1969, produced evidence that BCG and irradiated allogeneic leukaemia cells could lengthen the duration of remission in ALL in children, but the subsequent results of intensive combination chemotherapy together with prophylactic treatment of the central nervous system by Pinkel and his colleagues are so encouraging that immunotherapy is not being extensively used in this form of leukaemia at the moment. The situation in AML, particularly in adults, is completely different. The maintenance of remission with chemotherapy in this type of leukaemia is difficult and relapses occur quite rapidly. Various centres have now shown that both remission lengths and overall survival are significantly prolonged by using BCG with or without irradiated allogeneic leukaemia cells. The significance of these are reviewed and the problems for the future are discussed.