Gender and duration of disease differentiate responses to rituximab-dexamethasone therapy in adults with Immune Thrombocytopenia (ITP).

Adults often develop chronic immune thrombocytopenia (ITP) for which treatment order is uncertain. Rituximab and three cycles of dexamethasone (4R+3Dex) improve treatment responses and short-term disease control but long-term outcome is not known. In adults with ITP treated with 4R+3D, we sought long-term outcome and associated prognostic variables. Forty-nine adults treated at Weill-Cornell received 4R+3Dex. Their clinical characteristics were reviewed. Duration was median time to treatment failure; Kaplan-Meier estimates were developed. Vbeta Tcell receptor (VBTCR) repertoire was obtained after treatment in 36 patients. Patients were adults with ITP 18-64 years old, median age 37. The 27 females were twice as likely to have an ongoing response to 4R+3Dex (44.1%) as males (19.6%; P=0.009). For ITP duration < 12 months, 52.7% of patients had continuing responses to 4R+3Dex compared to 15.3% of patients with diagnosis > 12 months (P=0.02). Females with ITP duration of < 12 months had continuing responses in 78.6%, compared to males with < 12 months duration of ITP (21.2%). For patients with disease duration < 12 months, 67% of females had continuing responses, compared to 31% of males (P=0.004). Post-treatment polyclonal VBTCR was seen in 9/10 continuing responders (six female, three male) but only 13/26 relapsers/nonresponders (P=0.068). Durable remissions after treatment with 4R+3Dex were more frequent in female patients with < 12 months of ITP duration and those with polyclonal VBTCR after treatment, emphasizing the roles of duration of disease, gender and T cells in chronic ITP. Differences in pathophysiology of ITP by gender and by duration of ITP require further study. (C) 2016 Wiley Periodicals, Inc.