Chemotherapy or allografting for young adults with high-risk ALL?

To the editor:

The recent paper by Goldstone et al¹  reported the results of a prospective clinical trial testing the role of allogeneic hematopoietic cell transplantation compared with chemotherapy in the treatment of acute lymphoblastic leukemia (ALL) in adults. Using an unbiased donor/no donor analysis, the study showed that allogeneic transplantation is beneficial in preventing relapse and improving the 5-year survival in Ph-negative ALL patients up to the age of 55. This study is likely to change current practice and introduce the use of allografting for adults with ALL in first remission.

The issues started to arise when subsets of patients were analyzed, and the authors concluded that high-risk patients did not significantly benefit from having a donor. The wrinkle in this paper lies in the definition of risk that included age greater than 35 years and high blast counts at diagnosis. Older age is a risk factor for leukemia relapse, but it is also an important risk factor for nonrelapse mortality after transplantation. High blast count at diagnosis is a risk factor for leukemia relapse. It is, therefore, important to assess whether patients younger than 35 years at transplantation but with high blast counts at diagnosis would do better with allografting than chemotherapy. The analysis should be presented as published in Rowe et al,²  where patients are classified into 4 risk groups: younger than 35 years and low blast counts, younger than 35 years and high blast counts, older than 35 years and low blast counts, and older than 35 years and high blast counts.