Pediatric Treatment Guidelines for Philadelphia Positive (Ph+) Chronic Myelogenous Leukemia (CML): What Are They in Today’s Imatinib Era?
Authors: Burke Michael , Willert Jennifer , Desai Sunil J. , Kadota Richard 
Published: April 2020

Background: The treatment of pediatric Philadelphia positive (Ph+) chronic myelogenous leukemia (CML) in the era of the tyrosine kinase inhibitors (TKI) continues to evolve with the role of allogeneic hematopoietic cell transplantation (allo-HCT) in these patients becoming more controversial. Imatinib has completely replaced allo-HCT for adult CML patients presenting in first chronic phase, reserving HCT for TKI resistant and/or advanced stage patients (accelerated phase and blast crisis). Whether treatment strategies in 2008 have changed for CML in pediatrics, from heavily allo-HCT based to TKI based medical therapy, is presently unclear.

Methods: Thirty-two pediatric centers across the United States and Canada were surveyed regarding current treatment practices for CML in order to explore treatment practices in 2008. The survey targeted primary pediatric oncologists and bone marrow transplant physicians regarding their treatment approach for CML in terms of upfront therapy, utility of allo-HCT, use of TKI (including their role in the post-HCT setting) and how response to therapy was monitored.

Results: Twenty-three of the thirty-two centers completed the survey to provide a completion rate of 72% (Table 1). Sixty-three percent of survey responders recommended allo-HCT, when a matched sibling donor was available, for patients with CML in first chronic phase. Regarding the use of TKI in the post-HCT setting, 9 of 27 (33%) physicians reported using imatinib as maintenance therapy post-HCT as a means to prevent relapse. All physicians reported using PCR techniques for bcr-abl of either bone marrow, peripheral blood or both to monitor treatment response with frequencies ranging from monthly to every six months.

Conclusion: Treatment of pediatric CML appears variable and center dependent. This survey identified a trend toward less allo-HCT for CML in 2008 compared to years past. Despite the trend toward less HCT, the pediatric treatment consensus in 2008 for CML remains MSD allo-HCT when available. Use of imatinib was recognized by all survey responders as standard of care in upfront therapy, but the use of imatinib or other TKI in the post-HCT setting as maintenance therapy remains in question. Prospective pediatric clinical trials will be necessary to determine the optimal strategy for CML in children.

Table 1. Pediatric Centers

British Columbia’s Children’s Hospital Children’s Hospital of Pittsburgh Children’s Memorial Medical Center–Northwestern Cincinnati Children’s Hospital Medical Center City of Hope Columbia Presbyterian College of Phys & Surgeons Doernbecher Children’s Hospital-OHSU Duke University Medical Center Mayo Clinic Medical College of Wisconsin Nationwide Children’s Hospital Schneider Children’s Hospital St. Jude Children’s Research Hospital Stollery Children’s Hospital–Edmonton Texas Children’s Cancer Center at Baylor College of Medicine The Children’s Hospital of Philadelphia The University of Chicago Comer Children’s Hospital University of California at San Diego/Rady Children’s Hospital San Diego UCSF School of Medicine University of Florida University of Michigan–C.S. Mott Children’s Hospital University of Minnesota Children’s Hospital, Fairview Washington University–St. Louis