Feasibility of Combined Detection of Gene Mutations and Fusion Transcripts in Bone Marrow Trephines from Leukemic Neoplasms.

Chromosomal translocations resulting in fusion genes represent important oncogenic drivers and potential therapeutic targets in rare leukemia subtypes. Formalin-fixed, paraffin-embedded trephines are frequently used in hematologic diagnostic tests and provide relevant access to leukemic cells for further studies, for example, phenotyping in bone marrow fibrosis. However, high-throughput molecular analysis of nucleic acids obtained from this material is challenging, especially the reliable detection of RNA transcripts. Sixty-three formalin-fixed, paraffin-embedded bone marrow trephines of patients with chronic eosinophilic leukemia, chronic myeloid leukemia, acute myeloid leukemia, and myeloproliferative neoplasms were analyzed for gene mutations and the presence of fusion transcripts with a commercial amplicon-based next-generation sequencing approach. Fusion transcripts relevant for diagnosis and therapy could be detected and validated (by RT-PCR) in 25 patients (39.7%). Retrospectively selected material, up to 10 years old, was used for this purpose, and only one sample failed in the RNA analysis (1.6%). This study concludes that amplicon-based fusion transcript detection in bone marrow trephines is feasible and that bone marrow trephines taken for histologic assessment can also be applied for high-throughput molecular analysis.