Novel fusion between the breakpoint cluster region and platelet‐derived growth factor receptor‐alpha genes in a patient with chronic myeloid leukemia‐like neoplasm: undetectable residual disease after imatinib therapy

Rare patients suffering from myeloid neoplasms share clinical and cytological features indistinguishable from chronic myeloid leukemia (CML) but lack the BCR‐ABL1 fusion gene. Several studies provide evidence that alterations in genes encoding tyrosine kinase receptors such as the platelet‐derived growth factor receptor (PDGFR) may be involved in the pathogenesis of these disorders. Here we describe a patient with a rare CML‐like disease in whom we identified a novel in‐frame BCR‐PDGFRA rearrangement joining BCR exon 17 to PDGFRA exon 13, resulting in overexpression of PDGFRA. The design of a specific quantitative PCR assay to monitor the molecular response during treatment with imatinib, a multitargeted tyrosine kinase inhibitor (TKI) with activity against ABL, c‐Kit, and PDGFRA revealed an outstanding disease control with durably undetectable BCR‐PDGFRA transcripts. Multiple TKIs are currently available yet with distinct target profiles; thus, accurate molecular diagnosis and monitoring tools are essential to establish tailored treatments and assess response to therapy in this type of rare hematological malignancy.