Early response does not predict outcome in children and adolescents with chronic myeloid leukaemia treated with high-dose imatinib

Cases of Patients Treated in Countries With Limited Resources and Discussed by Experts of the International CML Foundation (iCMLf)-Case No. 1: A Boy Presenting With Priapism and Loss of Vision

Pediatric chronic myeloid leukemia (pCML) is a rare malignancy accounting for only 2%-3% of all childhood leukemias. Due to this rarity, familiarity with pCML is limited among most pediatric practitioners, including even pediatric hemato-oncologists. In low- and middle-income countries (LMICs), limited financial resources and limited data specific to pCML represent obstacles that healthcare providers must face in diagnosing and treating this rare condition in children. The International CML Foundation (iCMLf) is improving outcomes for people with CML in these countries where resources, diagnostics, and access to medicines may be limited (https://www.cml-foundation.org/lmic-programs.html). Virtual meetings with the purpose of teaching participating pediatricians from LMICs of defined geographical regions were organised by the iCMLf in 2023. At a virtual meeting of the South Asia region, the case of a 14-year-old Indian boy was presented diagnosed with CML in a chronic phase complicated by priapism and loss of vision in his left eye due to hyperleukocytosis. Key aspects of this case are discussed in-depth from the perspective of (i) a pediatric hemato-oncologist practicing in a high-income country, (ii) a pediatric hemato-oncologist practicing in a LMIC, (iii) an adult CML hematologist, and (iv) from the iCMLf in improving the care of children with CML worldwide. Thus by discussing a multifaceted complicated case of pCML in written form as well as pointing to the pediatric module of the iCMLf Knowledge Centre will hopefully contribute to minimize existing knowledge gaps in a rare pediatric malignancy.

Long-term safety and efficacy of imatinib in pediatric patients with chronic myeloid leukemia: single-center experience from China

Chronic myeloid leukemia (CML) is a rare disease among children. A retrospective study was conducted from November 2002 to March 2019 at a single institution in China. A total of 36 pediatric CML patients (25 male and 11 female) were enrolled. Median follow-up time was 51 months (range 8-144), and 5-year overall survival and event-free survival were 95.5 ± 4.4% and 88.9 ± 6.0%, respectively. Among the 25 patients whose response to imatinib mesylate (IM) was regularly monitored, 92.0% achieved complete hematologic response at 3 months, 80.0% achieved complete cytogenetic response at 12 months, and 64.0% achieved major molecular response at 18 months after IM therapy. A higher WBC count at diagnosis was associated with failure to achieve early molecular response (EMR). Height standard deviation score after long-term treatment was significantly and positively correlated with age at diagnosis and at the start of IM therapy. Overall, IM therapy was effective in treating pediatric CML, and WBC count at diagnosis might be an ideal predictor of EMR. Moreover, retardation of height and weight growth due to IM tended to affect patients younger than 9 years old at diagnosis, and longitudinal growth might normalize further into treatment.

Dasatinib in Pediatric Patients With Chronic Myeloid Leukemia in Chronic Phase: Results From a Phase II Trial

Purpose Safe, effective treatments are needed for pediatric patients with chronic myeloid leukemia in chronic phase (CML-CP). Dasatinib is approved for treatment of adults and children with CML-CP. A phase I study determined suitable dosing for children with Philadelphia chromosome-positive (Ph+) leukemias. Methods CA180-226/NCT00777036 is a phase II, open-label, nonrandomized prospective trial of patients < 18 years of age receiving dasatinib. There are three cohorts: (1) imatinib-resistant/intolerant CML-CP, (2) imatinib-resistant/intolerant CML in accelerated/blast phase or Ph+ acute lymphoblastic leukemia (n = 17), and (3) newly diagnosed CML-CP treated with tablets or powder for oral suspension. Major cytogenetic response > 30% for imatinib-resistant/intolerant patients and complete cytogenetic response (CCyR) > 55% for newly diagnosed patients were of clinical interest. Results Of 113 patients with CML-CP, 14 (48%) who were imatinib-resistant/intolerant and 61 (73%) who were newly diagnosed remained on treatment at time of analysis. Major cytogenetic response > 30% was reached by 3 months in the imatinib-resistant/intolerant group and CCyR > 55% was reached by 6 months in the newly diagnosed CML-CP group. CCyR and major molecular response by 12 months, respectively, were 76% and 41% in the imatinib-resistant/intolerant group and 92% and 52% in newly diagnosed CML-CP group. Progression-free survival by 48 months was 78% and 93% in the imatinib-resistant/intolerant and newly diagnosed CML-CP groups, respectively. No dasatinib-related pleural or pericardial effusion, pulmonary edema, or pulmonary arterial hypertension were reported. Bone growth and development events were reported in 4% of patients. Conclusion In the largest prospective trial to date in children with CML-CP, we demonstrate that dasatinib is a safe, effective treatment of pediatric CML-CP. Target responses to first- or second-line dasatinib were met early, and deep molecular responses were observed. Safety of dasatinib in pediatric patients was similar to that observed in adults; however, no cases of pleural or pericardial effusion or pulmonary arterial hypertension were reported.