ORIGINAL ARTICLE Pediatric standard-risk AML with fully matched sibling donors: to transplant in first CR or not? A Gassas 1 , S Afzal 1 , MK Ishaqi 1 , T Finkelstein-Shechter 1 , M Rojas 1 , A Dupuis 2 , L Sung 1 and J Doyle 1 1 Division of Haematology/Oncology/BMT, Hospital for Sick Children, University of Toronto, Ontario, Canada and 2 Division of Clinical Research Support Unit, Hospital for Sick Children, University of Toronto, Ontario, Canada Allogeneic hematopoietic SCT (HSCT) for children with standard-risk AML in first CR (CR1) is controversial. We reviewed 32 consecutive children with standard-risk AML who received matched sibling donor HSCT in CR1 from 1995 to 2004. With a median follow-up of 76 months (range: 36–114), 3 year EFS was 0.74 (95% confidence interval (CI): 0.57–0.88) and the overall survival was 0.81 (95% CI: 0.66–0.93). Only one patient died as a result of TRM. Larger studies, such as the MRC-UK 10 and 12, reported 60–62% EFS. Outcome of children with standard-risk AML transplanted from a matched sibling donor in CR1 is very encouraging with minimal toxicity. Bone Marrow Transplantation (2008) 42, 393–396; doi:10.1038/bmt.2008.182; published online 30 June 2008 Keywords: AML; hematopoietic SCT; first CR; matched sibling donor; children Introduction In recent years, there has been a significant improvement in the outcome of children with standard-risk AML treated with chemotherapy alone. This has been achieved by a combination of increasingly intensive anthracycline- and cytosine-based chemotherapy and advances in supportive care, which have allowed intensive chemotherapy to be delivered with less morbidity and mortality. 1 In the Medical Research Council of United Kingdom (MRC-UK) trials 10 and 12, children with standard-risk AML were allowed to proceed to hematopoietic SCT (HSCT) if there was a fully matched sibling donor. 2 Allogeneic HSCT enables the administration of high-dose chemotherapy to eradicate leukemia and provides the benefit of the GVL effect, and when using an HLA-matched sibling donor, HSCT has been considered to be the treatment of choice for children with AML in CR1. 3–5 However, with the excellent results obtained with chemotherapy and the known risks and long- term side effects of HSCT, the decision remains contro- versial. Although it is generally acceptable not to transplant children with favorable risk AML in CR1 and to transplant the poor-risk group with related or unrelated donors, the majority of the patients (more than 2/3) fall in the standard-risk group. In our institution and generally in North America, children with standard-risk AML and a fully matched sibling donor are usually offered HSCT in CR1. With the added GVL effect, their outcome is expected to be better than chemotherapy alone. However, increasing TRM from HSCT may change this balance. The current study examined the outcome of HSCT in children with standard-risk AML receiving fully matched sibling donors in CR1 to ascertain if it is justifiable to continue offering HSCT to these children despite the reasonably good results obtained with chemotherapy alone. Patients and methods This study was approved by our institutional review board. The health records of children who received HSCT for a diagnosis of standard-risk AML in the Hospital for Sick Children (Toronto) from November 1995 to November 2004 were reviewed. The definition of standard-risk was according to the following MRC-UK criteria: (1) no favorable cytogenetics; t(8;21), t(15;17) or inv (16) abnorm- alities; (2) no unfavorable cytogenetics; monosomy 7, monosomy 5, del (5q), abn (3q) and complex karyotype; (3) no resistant disease; 420% blast after the first course of chemotherapy. Patients with mixed lineage/bipheotypic acute leukemia, Down’s syndrome or M3 (acute promye- locytic leukemia) were excluded from the study. All patients were to be in morphological remission before HSCT. Donor sources were fully HLA-matched siblings. HLA matching consisted of either serologic or low-resolution molecular typing of HLA-A and HLA-B and molecular typing for DRB1 using high-resolution techniques. A fully matched sibling was defined as a 6/6 match on A, B and DRB1 loci. Unmanipulated BM was collected according to established methods. 6 All patients had indwelling central venous catheters, and the majority received nutritional support with total parenteral nutrition. Our institutional criteria to start total parenteral nutrition were as follows: if a child failed to maintain caloric and protein intake of 50% Received 22 March 2008; revised 29 April 2008; accepted 11 May 2008; published online 30 June 2008 Correspondence: Dr A Gassas, Division of Hematology/Oncology/ BMT, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8. E-mail: adam.gassas@sickkids.ca Bone Marrow Transplantation (2008) 42, 393–396 & 2008 Macmillan Publishers Limited All rights reserved 0268-3369/08 $32.00 www.nature.com/bmt