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Background: Angiosarcoma is a malignant neoplastic disease originating from or differentiating toward vascular endothelium, for which systemic pharmacologic treatment has limited durability. The molecular oncogenesis of angiosarcoma is often linked to inappropriate activations of vascular endothelial growth factor receptor (VEGFR) family members, which presents an opportunity for the use of therapy that selectively targets the machinery of vascular signaling. Methods: Hybridization capture of 3,320 exons of 182 cancer-related genes and the introns of 14 genes frequently rearranged in cancer was applied to more than 50 ng of DNA extracted from a formalin-fixed, paraffin-embedded biopsy of recurrent angiosarcoma and was sequenced to high, uniform coverage of 939x. Results: The angiosarcoma harbored amplifications of VEGFR2 (KDR) of 8 copies and VEGFR3 (FLT4) of 16 copies. The patient was initially treated with sorafenib, an inhibitor of VEGFR2, and developed progressive disease. The patient then received pazopanib, an inhibitor of VEGFR2 and VEGFR3 and experienced a potent antitumor response resulting in clinically stable disease for 6 months. Conclusions: This exceptional response to pazopanib treatment suggests that a subset of patients with angiosarcoma with genomic alterations in vascular signaling genes may respond well to pazopanib.

Acute promyelocytic leukemia (APL) is characterized by the fusion of retinoic acid receptor alpha (RARA) with promyelocytic leukemia (PML) or, rarely, other gene partners. This report presents a patient with APL with a novel fusion between RARA and the interferon regulatory factor 2 binding protein 2 (IRF2BP2) genes. A bone marrow examination in a 19-year-old woman who presented with ecchymoses and epistaxis showed morphologic and immunophenotypic features consistent with APL. PML oncogenic domain antibody was positive. Results of fluorescence in situ hybridization, conventional cytogenetics, reverse transcription–polymerase chain reaction (RT-PCR), and oligonucleotide microarray for PML-RARA and common APL variant translocations were negative. Next-generation RNA-sequencing analysis followed by RT-PCR and direct sequencing revealed distinct breakpoints within IRF2BP2 exon 2 and RARA intron 2. The patient received all-trans retinoic acid, arsenic, and gemtuzumab ozogamicin, and achieved complete remission. However, the disease relapsed 10 months later, 2 months after consolidation therapy. This is the first report showing involvement of IRF2BP2 in APL, and it expands the list of novel RARA partners identified in APL.

RNA-seq was used to identify the partner gene and confirm the presence of a BCR-PDGFRB fusion. Identification of this fusion product resulted in successful treatment and long-term remission of this myeloid neoplasm. Based on our results, we suggest that despite current WHO recommendations, screening for PDGFRB rearrangement in cases of leukocytosis with eosinophilia and no other etiologic explanation is necessary, even if the karyotype is normal.