A study aimed to capture prospective data, which is currently limited, on essential thrombocythemia (ET) progression to myelofibrosis (MF). The findings were presented at the Society of Hematologic Oncology 2024 Annual Meeting in Houston, Texas.
Researchers analyzed 1,237 patients who had ET (aged ≥60 years), who had a history of thromboembolic events (TEs), or who were receiving ET-directed therapy, except for aspirin alone. The primary end point of interest was ET-to-MF progression, which was defined as meeting at least one of the following criteria: fibrosis grade ≥2 and/or pathologic MF diagnosis from bone marrow biopsy; death from MF, myelodysplastic syndrome, or acute myeloid leukemia; circulating blasts >1% and new or worsening splenomegaly; or new or worsening splenomegaly and two or more of the following: white blood cell count (WBC) >11×109/L, hemoglobin <10g/dL, and platelet count <100×109/L.
The results showed that for patients with versus without ET-to-MF progression, there was no age difference at enrollment or diagnosis; however, the former had notably longer duration from diagnosis to enrollment and from diagnosis to study end (median, 7.9 vs 4.2 years, 12.7 vs 9.0 years, respectively; P=.001). The researchers observed that among patients tested for driver mutations, a higher percentage with versus without progression were JAK2-positive (80.6% [29 of 36] vs 69.7% [598 of 858]).
The findings also showed that among patients with versus without progression, mean hemoglobin was notably lower (12.5 vs 13.1 g/dL; P=.026), WBC counts were significantly higher (10.4×109/L vs 7.4×109/L; P<.001), and platelet counts were similar (418.6×109/L vs 455.0×109/L; P=.466). Moreover, the investigators observed that a lower percentage of patients with vs without progression had ≥1 TE (1.9% vs 3.7%), but a higher percentage had ≥1 hemorrhagic event (7.5% vs 1.3%).
“This analysis from MOST showed that 4.3% of patients had ET-to-MF progression over about five years of follow-up; at enrollment, these patients had longer disease duration, higher WBC counts, lower hemoglobin, but similar disease burden, versus patients without progression. These findings and further analysis of MOST data will add insight on disease progression and facilitate clinical management of patients with ET,” the researchers concluded.
Reference
Yacoub A, Lyons R, Braunstein E, et al. Progression to myelofibrosis (MF) in patients with essential thrombocythemia (ET): an analysis from the prospective Myelofibrosis and Essential Thrombocythemia Observational Study (MOST). Abstract #MPN-087. Presented at the Society of Hematologic Oncology 2024 Annual Meeting; September 4-7, 2024; Houston, Texas.