A Rare Chromosome Abnormality with der(16)t(1;16)(q12;q11.2) in Blast Crisis of Chronic Myeloid Leukemia.

Although tyrosine kinase inhibitors markedly improve the clinical outcome of chronic myeloid leukemia (CML), blast crisis in CML (CML-BC) still has a poor prognosis. Many chromosomal abnormalities have been reported in CML-BC and may contribute to therapeutic resistance, disease progression, and prognosis. Herein, we report a rare chromosome abnormality with der(16)t(1;16)(q12;q11.2) in CML-BC. It has been demonstrated that this chromosomal abnormality is associated with disease progression and poor prognosis in other malignancies, such as Ewing sarcoma. A 70-year-old man with CML who had been treated with imatinib and dasatinib was admitted to our hospital after complaining for several weeks of fatigue and dyspnea and diagnosed with CML-BC. His tumor cells presented additional chromosomal abnormality with der(16)t(1;16)(q12;q11.2), which has never been reported in CML cases. We successfully treated him using cytotoxic agents combined with ponatinib, and this chromosome abnormality was detected via G-banding. Our patient has lived for over 8 months without any progression with ponatinib treatment alone. Although the biological function of this chromosomal abnormality remains unclear, the satellite DNA of 1q12, which induces genomic instability in other malignancies, and the loss of 16q may contribute to the disease progression of CML in this case. In conclusion, this paper is the first to report on the case of CML-BC with der(16)t(1;16)(q12;q11.2).