CALR-mutant myeloproliferative neoplasms: insights from next-generation sequencing

Essential thrombocythemia and primary myelofibrosis belong to the group of BCR::ABL1-negative myeloproliferative neoplasms. The presence of mutations in the JAK2, CALR, and MPL genes is essential for the diagnosis of myeloproliferative neoplasms. These mutations are called "driver" mutations. However, not only leading mutations have been identified in patients with MPN, but also more than half of individuals with essential thrombocythemia and more than 80% of patients with myelofibrosis have additional mutations. One technique that makes it possible to find prognostic, predictive, and diagnostic indicators is next-generation sequencing. Coexisting mutations are associated with reduced response to therapy, shortened overall survival, and a higher risk of transformation to acute myeloid leukemia or myelofibrosis. The study group consisted of 42 patients with the diagnosis of BCR::ABL1-negative MPN and the presence of a mutation in the CALR gene. The research material was archival, and DNA was obtained from patients' peripheral blood. Forty genes (17 genes, 23 hotspots) were sequenced using the commercial kit AmpliSeq for Illumina Myeloid Panel applying the targeted next-generation sequencing approach. For the study, the Illumina MiniSeq platform was used. The analysis of the obtained genetic results was carried out using bioinformatics tools and genetic databases. We studied 42 CALR-positive ET (n = 28) and MF (n = 14) patients with NGS panel testing. The median age at diagnosis of the entire patient series was 58 years. Additional mutations were detected in 48% of patients in the whole cohort. The most frequently mutated genes in the study population were ASXL1, TET2, and DNMT3A, which are largely associated with epigenetic regulatory mechanisms. NGS panel studies represent a breakthrough in the diagnostic and prognostic evaluation of MPNs with CALR mutations. The ability to perform such a comprehensive study provides valuable information on the biology of the disease and the selection of the appropriate treatment regimen. The use of new technologies shows that not only driver mutations have clinical significance for the patient. NGS has the potential to increase the precision and effectiveness of diagnosis and prognosis.