Biomark Res 
Lewen M et al.  

Abstract

BACKGROUND:
Chronic myeloid leukemia (CML) comprises ~3 % of pediatric leukemia. Although therapy with tyrosine kinase inhibitors (TKIs) is highly effective for CML, multiple factors have been identified as predictive of treatment failure. Chromosomal abnormalities involving the MECOM locus at 3q26 portend therapy resistant disease in adults, yet have never been described in pediatric patients and have not been associated with T lymphoblastic progression.

CASE PRESENTATION:
We present a case of an 11-year-old boy with CML possessing the unique combination of T lymphoblastic transformation and a subclone harboring inv(3)(q21q26.2) at diagnosis. This is the first reported case of pediatric CML with inv(3)(q21q26.2) and the first case of T lymphoblastic progression associated with this karyotype. The patient was treated with single agent TKI therapy with robust initial response. Marrow histology at one month showed restoration of trilineage hematopoiesis and BCR-ABL RT-PCR at three months showed a 1.4 log reduction in transcript levels.

CONCLUSIONS: 
The karyotypic abnormality of inv(3)(q21q26.2) in CML is not restricted to adult patients. Moreover, while chromosome 3 abnormalities are markers of TKI resistance in adults, our patient showed a robust early response to single agent TKI therapy. This finding suggests pediatric CML with inv(3)(q21q26.2) may have distinct features and more favorable treatment responses than those described in adults.

The management of chronic myelogenous leukemia (CML) in children changed dramatically with the introduction of tyrosine kinase inhibitors (TKIs). Unfortunately, outcomes for patients presenting in an advanced stage-accelerated phase or blast crisis CML-continues to be poor, requiring chemotherapy and allogeneic hematopoietic stem cell transplant (HSCT) to attempt cure. Integration of TKIs in the therapy of advanced CML is still an area of active investigation. There are little published data on TKI use in children with advanced stage CML. We performed a retrospective review of all children treated at our institution between January 1, 2010 and June 30, 2013, and identified 5 children, age 12 to 18 years, with advanced stage CML. All patients were treated with a TKI before HSCT and TKIs were restarted post-HSCT in 4/5 with a goal of continuing until 2 years posttransplant. At time of HSCT all were in a morphologic and cytogenetic remission; 1 patient had also achieved molecular remission. All patients are alive and in molecular remission at an average of 38 months (range, 14 to 51 mo) following transplant. Our experience indicates that TKIs are safe and well tolerated in children both pretransplant and posttransplant and may improve outcomes in this aggressive disease. 

Pediatr Blood Cancer (epub ahead of print)
Mashan A et al. 

Abstract

An 11-year-old male was diagnosed with chronic-phase chronic myeloid leukemia (CML) in 1998 and received therapy with interferon-α2b and low-dose cytarabine. In 6 years, he progressed to lymphoid blast crisis and received induction chemotherapy with prednisolone, vincristine, daunorubicin, and l-asparaginase concomitantly with imatinib 400 mg/day, and continuation with vincristine + prednisolone, cytarabine + etoposide, vincristine + l-asparaginase, cyclophosphamide + etoposide, and 6-mercaptopurine + methotrexate. Complete molecular response (MR) was achieved and therapy was continued with imatinib 800 mg/day. He relapsed to chronic-phase CML after interruption of imatinib and regained MR after its restart. The patient is alive 17.5 years after CML diagnosis and 11.5 years after lymphoid blast crisis.