Long-term Follow-up of Busulfan, Etoposide, and Nimustine Hydrochloride (ACNU) or Melphalan as Conditioning Regimens for Childhood Acute Leukemia and Lymphoma

We retrospectively evaluated early and long-term complications of an intensified conditioning regimen consisting of busulfan and etoposide in combination with either nimustine hydrochloride (ACNU) (BVA regimen, n = 18) or melphalan (BVL regimen, n = 34) in 52 children with acute leukemia or non-Hodgkin’s lymphoma. With a median follow-up of 13.2 years after the BVA regimen and 8.1 years after the BVL regimen, 61% and 76% of patients, respectively, are in continuous complete remission. Transplantation-related mortality was 17% and 6% after the BVA and BVL regimens, respectively, and the corresponding relapse rates were 17% and 15%. The most common and severe toxicity was pulmonary complication in the BVA regimen, which was seen in 67% of patients and was life-threatening in 20%. Thirty-three percent of patients after the BVA regimen and 24% after BVL died of relapse or disease progression (n = 9), interstitial pneumonia (n = 2), fungal pneumonia (n = 1), or chronic graft-versus-host disease (n = 2). One of the long-term survivors developed secondary leukemia. A significant decrease in the height standard deviation score of more than 2 SD from diagnosis to the last follow-up was seen in 17% of the patients, with hypothyroidism in 15%, and alopecia in 42%. Because our experience is limited to a small heterogeneous population of patients who mainly underwent transplantation in the first remission, we cannot draw conclusions on the treatment’s effectiveness. The BVL regimen is tolerable, however, because no regimen-related death was observed, whereas the BVA regimen is not recommended because of the high incidence of pulmonary complications. The effectiveness of the BVL regimen requires further study.