Frequency and prognostic value of resistance/intolerance to hydroxycarbamide in 890 patients with polycythaemia vera.

Alvarez-Larrán A, Kerguelen A, Hernández-Boluda JC, et al.On behalf of the Grupo Español de Enfermedades Mieloproliferativas Filadelfia Negativas (GEMFIN)

Br J Haematol 2016;172:786-793

The authors assessed the clinical significance of resistance/intolerance to hydroxycarbamide (HC) in a series of 890 patients with polycythaemia vera (PV). Resistance/intolerance to HC was recorded in 137 patients (15·4%), consisting of: need for phlebotomies (3·3%), uncontrolled myeloproliferation (1·6%), failure to reduce massive splenomegaly (0·8%), development of cytopenia at the lowest dose of HC to achieve a response (1·7%) and extra-haematological toxicity (9%). With a median follow-up of 4·6 years, 99 patients died, resulting in a median survival of 19 years. Fulfilling any of the resistance/intolerance criteria had no impact on survival but when the different criteria were individually assessed, an increased risk of death was observed in patients developing cytopenia [Hazard ratio (HR): 3·5, 95% confidence interval (CI): 1·5–8·3,P = 0·003]. Resistance/intolerance had no impact in the rate of thrombosis or bleeding. Risk of myelofibrotic transformation was significantly higher in those patients developing cytopenia (HR: 5·1, 95% CI: 1·9–13·7,P = 0·001) and massive splenomegaly (HR: 9·1, 95% CI: 2·3–35·9, P = 0·002). Cytopenia at the lowest dose required to achieve a response was also an independent risk factor for transformation to acute leukaemia (HR: 20·3, 95% CI: 5·4–76·5, P < 0·001). In conclusion, the unified definition of resistance/intolerance to HC delineates a heterogeneous group of PV patients, with those developing cytopenia being associated with an adverse outcome.

This summary is prepared by Yahya Büyükaşık,M.D.

Universidad Autonoma de Nuevo Leon, Hematology Service, Hospital Universitario Monterrey, México
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