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.