Prognostic Value of Response to First-Line Hydroxyurea According to Ipset Stratification in Essential Thrombocythemia

• Published in: Blood 2024-11, Vol.144, p.241-241
• Main Authors: Santaliestra, Marta, Garrote, Marta, Noya, María Soledad, Pérez-Encinas, Manuel, Senin, María Alicia, Perez Lopez, Raul, Ferrer Marin, Francisca, Carreño, Gonzalo, Caballero Navarro, Gonzalo, Magro, Elena, Velez, Patricia, Cortes Vázquez, Miguel A., Moreto Quintana, Ana, Angona, Anna, Pastor Galan, Irene, Guerra, Jose María, Garcia Hernandez, M. Carmen, Mata, María Isabel, Stuckey, Ruth, Gómez Casares, Maria Teresa, Fox, Maria Laura, Cuevas, Beatriz, García Gutiérrez, Valentín, Triguero, Ana, Arellano-Rodrigo, Eduardo, Hernandez Boluda, Juan Carlos, Alvarez-Larran, Alberto
• Format: Article
• Language: English
• ISSN: 0006-4971
• DOI: 10.1182/blood-2024-198336

INTRODUCTION Essential thrombocythemia (ET) is the most frequent chronic myeloproliferative neoplasm and the one with the best prognosis. ET patients are classically stratified into two thrombotic risk categories based on age over 60 years and history of thrombosis. Recently, the increased thrombotic risk associated with JAK2 mutation has been incorporated into the revised IPSET-thrombosis scoring system. Hydroxyurea (HU) is the first-line treatment for the majority of patients with ET, but criteria for treatment change are not well-established. The prognostic value of the response according to the revised-IPSET thrombosis risk score has not been studied. OBJECTIVES Our aim was to analyze the prognostic impact of achieving complete hematological response (CHR) and resistance/intolerance (R/I) to HU, as defined by the European LeukemiaNet, in a contemporary cohort of 1080 patients from the Spanish registry of ET. Subgroup analyses were also conducted based on both classical and revised IPSET-thrombosis risk stratification. METHODS The main outcomes of the study were survival, the occurrence of thrombotic events, bleeding, and disease progression. The period at risk was defined as the time elapsed from HU start to the first event. RESULTS Patients were classified at the time of cytoreduction according to the classical risk scale (low- n=144, high-risk n=936) and revised IPSET-Thrombosis stratification (very low- n= 61, low- n=83, intermediate- n= 261, and high-risk n=675). With a median treatment duration of 5 years (IQR: 2.4-8.2), 720 (67%) patients achieved CHR and 219 (20%) developed R/I to HU. The median time to CHR was 352 days, with probabilities of CHR at 12 and 24 months being 51% and 61%, respectively. The probabilities of R/I to HU at 1, 3, and 5 years were 4%, 9%, and 13%, respectively. Patients achieving CHR had significantly longer survival compared to non-responders, both in the intermediate-risk category (median survival: 17 and 11 years, respectively, p