T he significance of basophilia across essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) has not been previously characterized. This led Lisa Yuen, MD, and colleagues to conduct a retrospective study examining a broad cohort of myeloproliferative neoplasms (MPNs) to determine basophilia’s associations with clinical and molecular features and patient outcomes. The researchers found that a more aggressive disease phenotype and poorer clinical outcomes were associated with higher levels among patients with MPNs. The findings were reported in the American Journal of Hematology.

The investigators analyzed data from 195 patients who were diagnosed with an MPN between 2008 and 2019. All cases were classified according to revised 4th edition World Health Organization classification.

The researchers defined basophilia as a relative or absolute increase in peripheral blood or bone marrow aspirate within 6 months of the patient’s first diagnostic biopsy.

Basophilia was present in 22% of patients. The investigators noted a lower incidence of basophilia in patients with ET and PV compared with patients with pre-fibrotic PMF, fibrotic PMF, post-ET MF, post-PV MF, or MPN-unclassifiable (8% vs 35%; P<0.001). Among the patients without basophilia at baseline, the researchers found that 12% subsequently developed basophilia within a median 19.6 months after the initial MPN diagnosis. Patients with basophilia were also significantly older (P<0.001) and had higher white blood cell count (P<0.001) and reticulin grade (P<0.001), lower hemoglobin levels (P=0.01), and lower platelet counts (P<0.001) than patients without basophilia.

Basophilia was also associated with more frequent abnormal cytogenetics (P<0.001), higher mean total of mutations detected by next-generation sequencing (P<0.001), and more frequent JAK2 (P<0.001), SF3B1 (P=0.0083), and SRSF2 (P=0.0159) mutations, but less frequent calreticulin mutations (P=0.0018). At a median follow-up of 63 months, overall survival (OS) and leukemia-free survival (LFS) were significantly shorter in the basophilia group (54 months and 46 months, respectively; P<0.001). The median OS and LFS remained shorter in the basophilia group when patients with ET and PV were excluded (P=0.003 and P=0.002, respectively).

“These results suggest that basophilia could represent an additional prognostic marker in patients with MPNs, by highlighting patients who may have shorter survival and higher risk of progression to blast phase than would be predicted by current risk modeling,” the researchers concluded.