Emerging concepts in the management of acute lymphoblastic leukaemia

Modern chemotherapy can cure more than 70 per cent of children with standard risk acute lymphoblastic leukaemia (ALL). Encouraging results are also reported in children with high risk ALL receiving intensive chemotherapy. Results in adults with ALL are less satisfactory, the long term survival is less than 35 per cent. Further dose intensification as possible in the setting of bone marrow transplantation (BMT) has increased the cure rate to 50 per cent in adult ALL. Allogeneic BMT has, however, besides the enhanced antileukaemia activity related to high dose therapy, additional antileukaemia effect related to immune mechanisms. Immune effects may be separated into three elements viz., an antileukaemia effect of graft vs host disease (GvHD), a separate antileukaemia effect of T cells and possibly a specific graft vs leukemia effect (GvL). These immune mediated antileukaemic effects offer a new potential therapeutic modality. For instance, the T cell antileukaemic effect of transplant could be achieved by transfusing radiated T cells or administering lymphokines. Alternatively autologous bone marrow could be manipulated in vitro prior to reinfusion. Manipulation might include activation of natural killer (NK) cells or lymphokine activated killer (LAK) activity. Another newer approach to treat ALL is the use of hemopoietic growth factors. Use of these factors prior to chemotherapy may increase the proportion of proliferating leukaemic stem cells. This would increase the efficacy of many drugs since most are active against proliferating cells. Hemopoietic regulatory factors could also be used to directly inhibit leukemic cell growth or to promote differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)