Effective treatment with imatinib for acute B-lymphoblastic leukaemia with EBF1-PDGFRB fusion
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LETTER TO THE EDITOR
Effective treatment with imatinib for acute B-lymphoblastic leukaemia with EBF1-PDGFRB fusion Mirei Horiuchi 1 & Masahiro Yoshida 1 & Kai Yamasaki 2 & Ryoko Sakagami 3 & Takane Aoyama 3 & Naoko Tatsumi 1 & Minako Tsutsumi 1 & Yosuke Nakaya 1 & Hoyuri Fuseya 1 & Takuro Yoshimura 1 & Yoshiki Hayashi 1 & Takafumi Nakao 1 & Takahisa Yamane 1 Received: 15 February 2020 / Accepted: 21 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Dear Editor, A 22-year-old male complained of slight fever and lymphadenopathy for over 2 weeks. Physical examination revealed cervical and inguinal lymphadenopathy. Laboratory study revealed a haemoglobin level of 11.5 g/dL, platelet count of 12 × 10 9/L, and a leukocyte count of 202 × 109 /L with 93.5% blast cells. A bone marrow aspiration (BMA) showed 96.4% lymphoblasts. The lymphoblasts were found to express cluster of differentiation (CD) 10, CD19, CD20, and HLADR, but not CD13, CD33, and CD34 by flow cytometry. Cytogenetic analysis using the G-banding technique showed 46, XY in 8 mitoses. The patient was, thus, diagnosed with B cell precursor acute lymphoblastic leukaemia (BCP-ALL) and treated according to the JALSG ALL-202-U paediatric protocol [1]. Induction therapy with dexamethasone, cyclophosphamide, vincristine, pirarubicin, and L-asparaginase was administered. Although lymphoblasts in the peripheral blood disappeared upon haematopoietic recovery, BMA revealed 59% lymphoblasts after induction therapy. The patient was immediately administered another round of induction therapy with cyclophosphamide, pirarubicin, cytarabine, and mercaptopurine. Nevertheless, 30% lymphoblasts remained in the bone marrow. Array-comparative genomic hybridization analysis (4 × 18 K CGH oligonucleotide microarray, Agilent Technologies, Santa Clara, CA, USA) of peripheral blood containing 93% blast cells obtained at day 9 of the first
* Masahiro Yoshida [email protected] 1
Department of Hematology, Osaka City General Hospital, Osaka, Japan
2
Department of Pediatric Hematology and Oncology, Osaka City General Hospital, Osaka, Japan
3
Clinical Research Center, Osaka City General Hospital, Osaka, Japan
induction therapy revealed 5q33 microdeletion with breakpoints located between the EBF1 and PDGFRB genes accompanied by intragenic IKZF1 deletion and PAX5 deletion (Fig. 1a, b). Fluorescent in situ hybridization analysis revealed split signals of PDGFRB (Fig. 1c). Finally, reverse transcription-polymerase chain reaction (RT-PCR) and direct sequencing, using primers described previously [2], revealed the fusion of EBF1 exon 14 (NM_001290360.2) to PDGFRB exon 11 (NM_002609.4) (Fig. 1d, e). Based on these results, 400 mg imatinib mesylate once daily with simultaneous hyper-CVAD was administered [3]. After just one course of combination therapy without additional toxicity due to imatinib, lymphoblasts were disappeared, and EBF1-PDGFRB transcript became undetectable by RT-PCR in the bone marrow. Thus, the patient achieved molecular complete remission
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