Contributions
Abstract: EP1111
Type: E-Poster Presentation
Session title: Myeloproliferative neoplasms - Clinical
Background
Essential thrombocythemia (ET) is rare in pediatric patients, with uncertain criteria for diagnosis, prognosis and treatment strategies in real-world clinical practice.
Aims
The study aimed at revealing the patterns of diagnosis, prognosis and treatment strategies in real-world clinical practice in a cohort of children diagnosed with ET in China, and trying to optimize the diagnostic and therapeutic regimens based on existing evidence.
Methods
A total of 86 pediatric patients (age≤16 years) with an initial diagnosis of ET according to the 2016 WHO diagnostic criterion were enrolled. A total of 137 genes associated with myeloid malignancies were analyzed in 55 children. The immunophenotype of bone marrow mononuclear cells was detected by flow cytometry. Informed consent was obtained from the guardians of the patients.
Results
The median age was 10 years (range 1-16 years). The JAK2 V617F mutation was positive in 16 patients (18.6%). The CALR mutations were found in 3 out of 62 (4.8%) patients. The MPL mutation was analyzed in 65 patients, and none of them was positive. Surprisingly, although bone marrow histology was consistent with a diagnosis of ET in all the 67 cases without driver molecular markers, a spontaneous normalization of the platelet count without cytoreductive therapy occurred in 7 cases (10.4%), after a median follow-up of 37 months (8-96 months). We found that several factors might be ‘true ET’-specific, but rarely seen or absent in those with spontaneous recovery, including palpable splenomegaly, presence of immunophenotypic abnormality (mainly showing reduced CD38 expression on myeloid blast cells and reduced CD36 expression on nucleated red blood cells), positive endogenous erythroid colonies, subnormal erythropoietin, and presence of molecular markers other than JAK2, CALR or MPL mutations (such as mutations in NRAS, ASXL1). In 79 patients still with sustained thrombocytosis, 4 children (5.1%) displayed major thrombosis, and 3 (3.8%) evolved to myelofibrosis. The International Prognostic Score of thrombosis for adults was not applicable to childhood patients, and so does the International Prognostic Score of survival. We found that severe splenomegaly was a risk factor of myelofibrosis transformation in childhood patients. The Efficacy and safety between pegylated interferon and regular interferon were compared for the first time in childhood patients. Similar efficacy was seen between pegylated interferon and regular interferon, but better tolerance was seen in children using pegylated interferon. Furthermore, pegylated interferon was still effective and tolerant in 8 children that were resistant or intolerant for regular interferon.
Conclusion
Based on the 2016 WHO diagnostic criterion for ET, several ‘true ET’-specific features might be considered for the diagnostic screening of childhood ET. Prognostic factors of thrombosis and survival in pegylated interferon were different from that in adult patients. Pegylated interferon has an extensive application prosperity for childhood ET.
Keyword(s): Children, Diagnosis, Essential Thrombocytemia, Pegylated Interferon
Abstract: EP1111
Type: E-Poster Presentation
Session title: Myeloproliferative neoplasms - Clinical
Background
Essential thrombocythemia (ET) is rare in pediatric patients, with uncertain criteria for diagnosis, prognosis and treatment strategies in real-world clinical practice.
Aims
The study aimed at revealing the patterns of diagnosis, prognosis and treatment strategies in real-world clinical practice in a cohort of children diagnosed with ET in China, and trying to optimize the diagnostic and therapeutic regimens based on existing evidence.
Methods
A total of 86 pediatric patients (age≤16 years) with an initial diagnosis of ET according to the 2016 WHO diagnostic criterion were enrolled. A total of 137 genes associated with myeloid malignancies were analyzed in 55 children. The immunophenotype of bone marrow mononuclear cells was detected by flow cytometry. Informed consent was obtained from the guardians of the patients.
Results
The median age was 10 years (range 1-16 years). The JAK2 V617F mutation was positive in 16 patients (18.6%). The CALR mutations were found in 3 out of 62 (4.8%) patients. The MPL mutation was analyzed in 65 patients, and none of them was positive. Surprisingly, although bone marrow histology was consistent with a diagnosis of ET in all the 67 cases without driver molecular markers, a spontaneous normalization of the platelet count without cytoreductive therapy occurred in 7 cases (10.4%), after a median follow-up of 37 months (8-96 months). We found that several factors might be ‘true ET’-specific, but rarely seen or absent in those with spontaneous recovery, including palpable splenomegaly, presence of immunophenotypic abnormality (mainly showing reduced CD38 expression on myeloid blast cells and reduced CD36 expression on nucleated red blood cells), positive endogenous erythroid colonies, subnormal erythropoietin, and presence of molecular markers other than JAK2, CALR or MPL mutations (such as mutations in NRAS, ASXL1). In 79 patients still with sustained thrombocytosis, 4 children (5.1%) displayed major thrombosis, and 3 (3.8%) evolved to myelofibrosis. The International Prognostic Score of thrombosis for adults was not applicable to childhood patients, and so does the International Prognostic Score of survival. We found that severe splenomegaly was a risk factor of myelofibrosis transformation in childhood patients. The Efficacy and safety between pegylated interferon and regular interferon were compared for the first time in childhood patients. Similar efficacy was seen between pegylated interferon and regular interferon, but better tolerance was seen in children using pegylated interferon. Furthermore, pegylated interferon was still effective and tolerant in 8 children that were resistant or intolerant for regular interferon.
Conclusion
Based on the 2016 WHO diagnostic criterion for ET, several ‘true ET’-specific features might be considered for the diagnostic screening of childhood ET. Prognostic factors of thrombosis and survival in pegylated interferon were different from that in adult patients. Pegylated interferon has an extensive application prosperity for childhood ET.
Keyword(s): Children, Diagnosis, Essential Thrombocytemia, Pegylated Interferon