Monitoring Molecular Response, Minimal Residual Disease And Clonal Structures In Polycythemia Vera Patients Treated With Interferon Alpha

Polycythemia vera (PV) is a myeloproliferative neoplasm (MPN) primarily characterized by an elevated red blood cell count, consequently to clonal expansion of myeloid progenitor cells driven almost exclusively by a mutation of a specific single nucleotide in JAK2 exon 14 (JAK2-V617F). JAK2-V617F mutational burden therefore represents a surrogate measure for the size of the "liquid tumor" underlying PV, i.e. the amount of malignant cells in the peripheral blood. We previously reported on sustained molecular responses (MR) in PV patients on interferon alpha (IFNa) based therapies. Monitoring MR is crucial for understanding the therapeutic potential of IFNa and can be an important parameter in future PV patient care. Thus, highly sensitive laboratory techniques providing most accurate quantification at lowest limit of detection (LOD) are required. Here we evaluate four different methods for JAK2-V617F mutational burden monitoring, which are digital droplet PCR (ddPCR), next-generation sequencing (NGS), quantitative PCR (qPCR) and allele-specific PCR (AS-PCR). Moreover, using an NGS-based approach we investigate the patients' clonal composition by targeted re-sequencing involving 54 genes in longitudinal patient samples.