The role of allogeneic stem cell transplantation for adult acute lymphoblastic leukemia

Acute lymphoblastic leukemia remains a challenging disease in adults. With modern multi-drug induction chemotherapy regimens, complete remission can be achieved in most patients. However, without additional therapy at the time of the first remission, most patients will eventually relapse. Regardless of the treatment option chosen at the time of relapse, outcomes after relapse are poor, with only around 10% of all patients surviving after relapse. Thus, decision-making at the time of achieving the first complete remission is critical. Allogeneic stem cell transplantation is highly effective at preventing relapse, but with significant treatment related toxicity. Ongoing chemotherapy in the form of consolidation and maintenance may be less effective at preventing relapse, but with lower toxicities. Thus, the superiority of allogeneic stem cell transplantation must be balanced against the lower toxicity of consolidation chemotherapy. This decision is further complicated by rapid changes in the field of hematopoietic stem cell transplantation, such as the use of reduced intensity conditioning regimens and alternative stem cell sources such as cord blood transplants. The available evidence suggests that allogeneic transplantation is a viable treatment option for patients in first complete remission, with overall survival superior to traditional consolidation and maintenance chemotherapy. However, whether transplantation based post-remission therapy is superior to modern, pediatric-based non-transplant chemotherapy regimens remains unclear.