Protease inhibitors-based therapy induces acquired spherocytic-like anemia and ineffective erythropoiesis in chronic HCV patients

Background & Aims: The addition of protease inhibitors, boceprevir (BOC)or telaprevir (TRV), to peg-interferon and ribavirin (PR) increases the incidenceof anaemia in patients with chronic hepatitis C virus (HCV) infection.Although genetic variants in inosine triphosphatase (ITPA) gene have beenlinked to the haemolytic anaemia induced by PR, the mechanism sustainingsevere anaemia during triple therapy is still unknown. This study aims to elucidatethe molecular mechanisms underlying anaemia in chronic HCVpatients with combined therapy. Methods: We studied 59 patients withchronic HCV genotype-1: 29 treated with TRV/PR and 30 with BOC/PR. Weevaluated biochemical and haematological parameters, red cell index at baseline,4, 12, 16 and 24 weeks of treatment; in a subgroup, we performed functionalstudies: osmotic fragility, red cell membrane protein separation, massspectrometry analysis, quantification of erythroid microparticles release.IL28B and ITPA polymorphisms were also evaluated. Results: We foundearly acute normochromic normocytic haemolytic anaemia (4–8 weeks) followedby a late macrocytic hypo-regenerative anaemia with inappropriatelow reticulocyte count (12–24 weeks). Studies on red cells revealed: (i) presenceof spherocytes; (ii) increased osmotic fragility; (iii) abnormalities in redcell membrane protein composition; (iv) reduced membrane-cytoskeletonstability; (v) increased release of erythroid microparticles. ITPA polymorphismsimpacted only the early phase of anaemia. Conclusions: The bimodalpattern of anaemia in chronic HCV patients on triple therapy might bebecause of acquired spherocytic-like anaemia in the early phase, followed byhyporegenerative anaemia, most likely related to the combined effects of PRand TRV or BOC on erythropoiesis.