Aggressive B-cell lymphomas in patients with myelofibrosis receiving JAK1/2 inhibitor therapy

Edit Porpaczy, Sabrina Tripolt, Andrea Hoelbl-Kovacic, Bettina Gisslinger, Zsuzsanna Bago-Horvath, Emilio Casanova-Hevia, Emmanuelle Clappier, Thomas Decker, Sabine Fajmann, Daniela A. Fux, Georg Greiner, Sinan Gueltekin, Gerwin Heller, Harald Herkner, Gregor Hoermann, Jean-Jacques Kiladjian, Thomas Kolbe, Christoph Kornauth, Maria-Theresa Krauth, Robert Kralovics, Leonhard Muellauer, Mathias Mueller, Michaela Prchal-Murphy, Eva Maria Putz, Emmanuel Raffoux, Ana-Iris Schiefer, Klaus Schmetterer, Christine Schneckenleithner, Ingrid Simonitsch-Klupp, Cathrin Skrabs, Wolfgang R. Sperr, Philipp Bernhard Staber, Birgit Strobl, Peter Valent, Ulrich Jaeger, Heinz Gisslinger and Veronika Sexl

Key points

  • JAK1/2 inhibitor treatment in myelofibrosis is associated with an increased risk for aggressive B-cell lymphomas.

  • Patients at risk have a pre-existing B-cell clone in their bone marrow which can be identified by PCR.


Inhibition of Janus-kinase 1/2 (JAK1/2) is a mainstay to treat myeloproliferative neoplasms (MPN). Sporadic observations reported the co-incidence of B-cell non-Hodgkin lymphomas during treatment of MPN with JAK1/2 inhibitors. We assessed 626 MPN patients including 69 with myelofibrosis receiving JAK1/2 inhibitors for lymphoma development. B-cell lymphomas evolved in 4/69 patients (5.8%) upon JAK1/2 inhibition compared to 2/557 (0.36%) with conventional treatment (16-fold increased risk). A similar 15-fold increase was observed in an independent cohort of 929 MPN patients. Considering primary myelofibrosis only (N=216), 3 lymphomas were observed in 31 inhibitor-treated patients (9.7%) versus 1/185 controls (0.54%). Lymphomas were of aggressive B-cell type, extra-nodal or leukemic with high MYC expression in the absence of JAK2 V617F or other MPN-associated mutations. Median time from initiation of inhibitor therapy to lymphoma diagnosis was 25 months. Clonal immunoglobulin gene rearrangements were already detected in the bone marrow during myelofibrosis in 16.3% of patients. Lymphomas occurring during JAK1/2 inhibitor treatment were preceded by a pre-existing B-cell clone in all 3 patients tested. Sequencing verified clonal identity in 2 patients. The effects of JAK1/2 inhibition were mirrored in Stat1-/- mice: 16/24 mice developed a spontaneous myeloid hyperplasia with the concomitant presence of aberrant B-cells. Transplantations of bone marrow from diseased mice unmasked the outgrowth of a malignant B-cell clone evolving into aggressive B-cell leukemia-lymphoma. We conclude that JAK/STAT1 pathway inhibition in myelofibrosis is associated with an elevated frequency of aggressive B-cell lymphomas. Detection of a pre-existing B-cell clone may identify individuals at risk.

  • Submitted October 13, 2017.
  • Accepted March 7, 2018.