Gender and duration of disease differentiate responses to rituximab-dexamethasone therapy in adults with immune thrombocytopenia.

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. Am. J. Hematol. 91:907-911, 2016.