The Association Of Lymphocyte Phenotypes And Outcomes After Discontinuing Eltrombopag In Immune Thrombocytopenia

Aim Eltrombopag is a highly effective treatment for immune thrombocytopenia (ITP). Cases of durable remission after the discontinuation of eltrombopag in adult ITP have recently been reported; however, the frequency and mechanisms responsible for this phenomenon remain unknown. In the present study, we examined the phenotypes of lymphocytes in ITP to clarify whether they predict outcomes after the discontinuation of eltrombopag.Methods We analysed 56 adult ITP patients treated with eltrombopag at our hospital between January 2008 and January 2020. Patients' characteristics at the initiation and discontinuation of eltrombopag, the prognostic significance of lymphocytes and other factors were evaluated.Results A total of 38 patients showed complete response (CR). Eltrombopag was discontinued in 28 of 38 patients who achieved CR. Among the 28 patients, 12 (42.8%) had an immediate relapse after discontinuing eltrombopag and 16 (57.2%) showed sustained response without additional ITP therapy, despite discontinuing eltrombopag, with a median follow-up of 42 months. No significant differences were observed in platelets, the median duration of eltrombopag, the absolute number of T, B and NK cells at the initiation of eltrombopag between patients who sustained response and those who relapsed after discontinuing eltrombopag. However, the number of B and NK cells at the discontinuation of eltrombopag was higher in patients who sustained response than in those who relapsed (P = .022 and P = .012 respectively).Conclusions The present results indicate that the absolute number of B (>= 0.20 x 10(9)/L) and NK (>= 0.30 x 10(9)/L) cells at the discontinuation of eltrombopag contributes to the prediction of outcomes.