Germline Genetic Factors Influence Outcome of Interferon Alpha Therapy in Polycythemia Vera.

Interferon alpha (IFNα) based therapies can induce hematologic and molecular responses in polycythemia vera (PV); however, patients do not respond equally. Germline genetic factors have previously been implicated in differential drug response. We addressed the effect of common germline polymorphisms on hematologic and molecular response (HR/MR) in PV therapy within the PROUD-PV and CONTINUATION-PV studies including 122 patients with PV receiving ropeginterferon alfa-2b. Genome-wide association studies using longitudinal data on HR and MR over 36 months follow-up did not reveal any associations at genome-wide significance. Further, we performed targeted association analyses at the interferon lambda 4 (IFNL4) locus, well known for its role in hepatitis C viral clearance and recently reported to influence HR during therapy of myeloproliferative neoplasms. While we did not observe any association of IFNL4 polymorphisms with HR in our study cohort, we demonstrated a statistically significant effect of the functionally causative IFNL4 diplotype (haplotype pair including the protein-coding variants rs368234815/rs117648444) on MR (p=3.91x10-4; OR=10.80; 95%CI:[2.39-69.97]) as reflected in differential JAK2V617F mutational burden changes according to IFNL4 diplotype status. Stratification of PV patients based on IFNL4 functionality may allow for optimizing patient management during IFNα treatment.