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

We investigated the predictive value of the 3-month BCR-ABL1 transcript levels in terms of responses and outcome of 44 children and adolescents (<18 years at diagnosis) with chronic myeloid leukemia (CML) treated with high-dose imatinib (IM) (340 mg/m2/day). The transcript cutoff levels of 1% and 10% BCR-ABL1 IS were not predictive of either complete cytogenetic response at any time, overall molecular response (MR) and complete MR (CMR), and progression-free survival probabilities at 5 years. The 3-month transcript levels in children and adolescents with CML treated with high-dose IM do not appear to be informative for the prediction of outcomes

High Dose Imatinib Is Effective In Children and Adolescents With Chronic Myelogenous Leukemia In Chronic Phase. The Italian Experience

Imatinib (IM) is an established first-line treatment for children with chronic myeloid leukemia (CML). However, the most effective dosage and duration of IM treatment are not well defined. This study was designed to evaluate the response to high-dose IM and long-term outcome in pediatric CML patients, previously untreated or resistant to IFN. Patients aged &lt;18 years with a diagnosis of CML in chronic phase (CP) were treated with IM at a dosage of 340 mg/m2/day. Cytogenetic analysis was performed on bone marrow (BM) cells before and during IM therapy, at planned intervals; quantitative RT-PCR was assessed on peripheral blood (PB) monthly and on BM every 3 months, according to the European LeukemiaNet recommendations for minimal residual disease quantification. Major molecular response (MMR) is defined as &lt;0.1% BCR-ABLIS, while complete MR (CMR) is considered as &lt;0.01% BCR-ABLIS. From March 2001 to February 2013, 45 CML patients in CP (18 females, 27 males; median age: 119/12 years) were recorded from 9 Italian pediatric centers. Eight patients had previously received IFN. IM was started in all patients, including 16 with an HLA-matched sibling. The dosage was modulated according to hematologic toxicity and/or appearance of WHO &gt;2 side- effects, mostly during the first 6 months of treatment (median administered dose: 309 mg/m2/day). Hematologic toxicity (medullary hypoplasia[n=1], neutropenia [n=11] and/or thrombocytopenia [n=6], anemia [n=1]) was observed in14/44 evaluable patients (32%); 13 patients (29.5%) experienced isolated or combined side effects: arthralgia/myalgia (n=10), nausea (n=1), vomiting (n=1), diarrhea (n=1), hepatitis (n=1), edema (n=1). After 3 months of IM treatment, 7/25 of tested patients (28%) obtained complete cytogenetic response (CCyR). Overall, 34/36 evaluable patients (94%) obtained a CCyR at a median time of 6 months. A molecular response (&lt;0.1% BCR-ABLIS) was achieved in 21/26 tested patients (81%) on PB and in 30/33 evaluable patients (91%) on BM. Seventeen of 26 patients (65%), including 2 with a HLA-matched sibling, obtained a CMR on PB cells and 19/33 (55%) on BM cells at a median time of 15 and 19 months, respectively. With the aim of reducing the risk of longitudinal growth impairment or to improve treatment compliance, 9 patients with sustained CMR and 2 adolescents with MMR lasting &gt;12 months received IM at the same daily dosage for 3 weeks a month (intermittent therapy). IM given without interruption was resumed in 3 of these 9 patients because of an increased BCR-ABL transcript. The growth rate showed a delay in height, which recovered over time, in 6 children who received IM prior to puberty. Overall, IM was stopped in 22/44 evaluable patients (50%) because of various reasons: stem cell transplant (SCT) in 8 patients (3 in CP, 1 in CCyR, 3 in MMR, 1 in CMR); hematologic (n=2) or extra-hematologic toxicity (n=2) (WHO grading &gt;3) during the first 6 months in 4; recurrent disease in 6 (3 increased BCR-ABL transcript, 2 cytogenetic relapse,1 blast crisis [BC]); no response in 1; CMR ( &lt;0.0032% BCR-ABL IS) lasting &gt;88 months in 2 and pancreatitis in 1 patient in CMR for 75 months. Twelve patients underwent a SCT after a median time of 8 months: 8 from an identical siblings (5 responders to IM [1 CMR, 3 MMR, 1 CCyR]), 3 MUD (2 in CCyR and 1 in MMR) and 1 cord blood in CCyR after chemotherapy for CB. Three patients, transplanted from an identical sibling, had disease recurrence after 24 (molecular relapse), 36 (cytogenetic relapse) and 83 (BC) months, respectively. At the last follow-up, all patients are alive (CMR= 25; MMR=14; CCyR=3; minor CyR=2; too early=1) at a median of 52 months (range: 3-146). Of 42 patients evaluable for treatment, 23 are receiving IM at a dosage of 340 mg/m2 (4 intermittent IM); 11 are in CMR without any treatment (8 after SCT; 3 at 32, 33 and 50 months after IM discontinuation); 4 are in treatment with dasatinib, 3 with nilotinib and 1 with IFN. In our experience, higher dose IM is an effective treatment for childhood CP CML, associated with sustained responses. Moreover, IM can be safely discontinued in pediatric CML patients with a deep CMR lasting more than 7 years. For patients candidates to a SCT, IM provides a safe bridging option to transplant, at no increased risk. Since patients may lose their response, a close and regular monitoring should be performed, mostly for those who stop IM, as SCT and new TK inhibitors may be successfully employed in patients failing IM

Are all cases of paediatric essential thrombocythaemia really myeloproliferative neoplasms? Analysis of a large cohort

Sporadic essential thrombocythaemia (ET) is rare in paediatrics, and the diagnostic and clinical approach to paediatric cases cannot be simply copied from experience with adults. Here, we assessed 89 children with a clinical diagnosis of ET and found that 23 patients (258%) had a clonal disease. The JAK2 V617F mutation was identified in 14 children, 1 child had the MPL W515L mutation, and 6 had CALR mutations. The monoclonal X-chromosome inactivation pattern was seen in six patients (two with JAK2 V617F and two with CALR mutations). The other 66 patients (742%) had persistent thrombocytosis with no clonality. There were no clinical or haematological differences between the clonal and non-clonal patients. The relative proportion of ET-specific mutations in the clonal children was much the same as in adults. The higher prevalence of nonclonal cases suggests that some patients may not have myeloproliferative neoplasms, with significant implications for their treatment

Long-term results of high-dose imatinib in children and adolescents with chronic myeloid leukaemia in chronic phase: The Italian experience

Imatinib mesylate (IM) is used for the management of childhood chronic myeloid leukaemia (CML). The most effective dosage of IM and its long-term efficacy in children are not well defined. The purpose of this multicentre study is to report on the long-term results of high-dose IM (340 mg/m2 /d) in CML patients in chronic phase (CP-CML) aged <18 years at diagnosis. A total of 47 CP-CML patients with a median age at diagnosis of 11 years 9 months were enrolled in nine Italian centres. Complete cytogenetic response was achieved in 91.5% of the evaluable patients at a median time of 6 months. BCR-ABL1 International Scale 64 0.1% (major molecular response; MMR) and 640.01% (molecular response; MR) at 12 months were 66.6% and 33%, respectively. During follow-up, MMR and MR were achieved in 78.6% and 61% of children, respectively. IM was safely discontinued in 3 long-term treated children with a durable MR. Twelve patients (eight cytogenetic/molecular responders) underwent stem cell transplantation. The progression-free survival probabilities at 96 months for responding patients who continued IM and for those transplanted were 60% and 50%, respectively. After a median follow-up of 52 months (range 3-146), all patients are alive. High-dose IM is a long-term effective therapy in children and adolescents with CP-CML