April 21, 2025
Sarah Dingli, Saubia Fathima, Priyansh Faldu, Naseema Gangat, David Dingli & Ayalew Tefferi
Primary myelofibrosis (PMF) is a myeloid neoplasm that is currently classified in the category of JAK2 mutation-prevalent myeloproliferative neoplasms (JAK2-MPNs) [1]; other members of JAK2-MPNs include essential thrombocythemia (ET) and polycythemia vera (PV). JAK2-MPNs are characterized molecularly by JAK-STAT activating mutations, involving JAK2, CALR, and MPL genes, and morphologically by trilineage myeloid proliferation in the bone marrow (BM) that is accentuated by megakaryocyte proliferation and atypia [2]. Peripheral blood (PB) manifestations of JAK2-MPNs include leukocytosis, thrombocytosis, and/or erythrocytosis while other disease features include splenomegaly, thrombosis, bleeding, microvascular disturbances, pruritus, and constitutional symptoms. Patients with MPN are at risk for premature death and disease progression into a fibrotic or leukemic disease phase [3]. Disease complications in JAK2-MPNs are most severe in PMF where median survival is estimated at 4.4 years and leukemic progression at 9%, at a median follow-up of 3.2 years [4].
Leukocytosis, in general, has long been identified/suspected as a risk factor for a number of disease complications in JAK2-MPNs including overall and leukemia-free survival [5, 6], disease progression [7, 8], thrombosis risk [9,10,11], and extramedullary hematopoiesis [12]. Considering the multicomponent nature of leukocytes, more recent studies in JAK2-MPNs have appropriately looked into the differential prognostic impact of absolute neutrophil (ANC) [13,14,15], monocyte (AMC) [13, 16,17,18,19], and lymphocyte (ALC) counts [13,14,15]. By comparison, fewer studies have reported on the prognostic contribution of absolute basophil (ABC) or eosinophil (AEC) counts in JAK2-MPNs, in general, and in PMF, in particular, not associated with tyrosine kinase fusion genes [20,21,22,23,24]. On the other hand, the prognostic relevance of basophilia in chronic myeloid leukemia (CML) is well established and is taken under consideration in defining accelerated phase CML [25, 26]. In the current study, we utilized a large Mayo Clinic database of patients with PMF in order to describe the prevalence and the clinical, molecular, and prognostic correlates of ABC and AEC.
