Patients with myeloproliferative neoplasms treated with Janus-kinase (JAK) 1/2 inhibitors may be at significantly increased risk of aggressive B cell non-Hodgkin lymphomas, according to a study published in Blood.
A retrospective cohort study of 626 Viennese patients with myeloproliferative neoplasms – 69 of whom were treated with JAK1/2 inhibitors – found that 4 of the 69 patients (5.8%) developed aggressive B-cell lymphoma, compared with just 2 patients (0.36%) in the rest of the group. This represented a significant, 16-fold higher risk of aggressive B cell lymphoma associated with JAK1/2 inhibitor therapy (P = .0017).
The lymphoma was diagnosed within 13-35 months of starting JAK1/2 inhibitors. In three patients, the disease was in the bone marrow and peripheral blood, one patient had it in mammary tissue, and another had it in mucosal tissue. All four lymphomas showed positive MYC and p53 staining.
All four patients had been treated with ruxolitinib, one was also treated with fedratinib, and three of the four had been pretreated with alkylating agents.
Meanwhile, a second retrospective cohort study in Paris of 929 patients with myeloproliferative neoplasms, reported in the same paper, found that 3.51% of those treated with ruxolitinib developed lymphoma, compared with 0.23% of conventionally-treated patients.
Using archived bone marrow samples from 54 of the 69 patients treated with JAK1/2 inhibitors, researchers discovered that 15.9% of them – including three of the B-cell lymphoma patients (the fourth was not tested) – had a preexisting B cell clone. This was present as early as 47-70 months before the lymphoma diagnosis.
“In patients, the clonal B-cell population was present as long as 6 years before overt lymphoma and preceded JAK1/2 inhibition which offers the opportunity to determine patients at risk,” wrote Edit Porpaczy, MD, of the Comprehensive Cancer Center at the Medical University of Vienna, and her coauthors. “Targeted inhibition of JAK-STAT signaling appears to be required to trigger the appearance of the B-cell clone as other treatments eliminating the myeloid cell load in men do not exert a comparable effect.”
In the Viennese cohort, three of the lymphomas were aggressive CD19+ B-cell type, and the fourth was a nonspecified high-grade B-cell lymphoma.
Researchers also looked at the effects of JAK1/2 inhibition in STAT1-/- mice, and found that two-thirds developed a spontaneous myeloid hyperplasia with the concomitant presence of aberrant B-cells.
“Upon STAT1-deficiency myeloid hyperplasia is paralleled by the occurrence of a malignant B-cell clone, which evolves into disease upon bone-marrow transplantation and gives rise to a leukemic lymphoma phenotype,” the authors wrote.
The study was supported by the Austrian Science Fund, the Anniversary Fund of the Austrian National Bank and the WWTF Precision Medicine Program. Several authors reported support, funding or advisory board positions with the pharmaceutical industry.
SOURCE: Porpaczy E et al. Blood. 2018 Jun 14. doi: 10.1182/blood-2017-10-810739.