Abstract 3984: Novel t(X;21)(q26;q22) detected in a case of acute unclassifiable leukemia by application of anchored multiplex PCR-based next-generation sequencing

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA In this study, we demonstrate real-time clinical application of novel anchored multiplex PCR (AMP) technology in hematologic disease. A 78-year-old man with a history of hairy cell leukemia treated with Cladribine (2013) and bladder cancer (2014) developed dyspnea in August 2015. Work up revealed bicytopenia and leukocytosis. Outside bone marrow biopsy was read as B lymphoblastic leukemia/lymphoma. Rebiopsy was performed at our NCI-designated cancer center with extensive work up resulted in reclassification as acute unclassifiable leukemia (rare) with deferral to molecular diagnostics for guidance regarding classification. MLL, BCR-ABL, and MDS FISH panel were negative. Next generation sequencing (NGS) interrogating more than 400 genes showed FLT3-ITD, truncation of RUNX1 exon 6, ASXL1 p.G646Wfs*12, MLL p.V297L, and EZH2 p.V674M and p.C443Y mutations. The molecular profile favored therapy-related AML. Interestingly, cytogenetics revealed 46,Y,t(X;21)(q26;q22)[20]. FISH confirmed RUNX1 rearrangement but the partner was unknown. The t(X;21)(q26;q22) appears to be novel. However, the rare t(3;21)(q26.2;q22) has been cited to segregate with therapy-related MDS/AML. Subsequent aberrant activation of RUNX1 and MECOM is postulated to be pivotal in pathogenesis. Therefore, it is of great interest to determine the translocation partner associated with RUNX1 in our case. This type of analysis is not easily amenable to either Sanger or conventional NGS approaches. Fortuitously, with the recent advent of AMP technology (Archer FusionPlex) novel fusion detection has become possible. AMP was key in the characterization of this sample and promotes discovery of novel fusions by targeting one (known) of the two genes involved in a translocation event. Application of this cutting edge technology lead to the discovery of the novel fusion RUNX1-G6PD in this case. The identity of the novel fusion partners was supported by the breakpoints originally observed by the karyotype analysis. G6PD has been previously reported to be upregulated in acute leukemia. This discovery raises the possibility convergent pathogenic pathways and carries potential biological, diagnostic, and therapeutic implications. Citation Format: Laura Johnson, Helen Wang, Katelyn Trifilo, Brian Kudlow, Peter R. Pappenhausen, Mohammad Hussaini. Novel t(X;21)(q26;q22) detected in a case of acute unclassifiable leukemia by application of anchored multiplex PCR-based next-generation sequencing. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3984.