Effectiveness and Safety of Low Dose Eltrombopag Twice Weekly in ITP Patients That Achieved CR after 50mg Daily Standard Dose

Introduction. Eltrombopag is an oral, non-peptide thrombopoietin receptor agonist that has been shown efficacy and safety in chronic immune thrombocytopenia (ITP) patients not responding to previous therapy , by raising the platelets count in both continued long-term administration and in a repeated short-term administration. However, when eltrombopag is discontinued, platelet counts usually return to baseline within 2 weeks. As reported in different case series only 15 % of patients achieve a durable response after treatment discontinuation. The aims of this study was to evaluate the efficacy and safety of eltrombopag given at a dose of 25 mg every 3 days as maintenance therapy in responding patients after an initial standard dose of 50 mg orally once daily.

Methods. A total of 7 consecutive adult patients, female (70 %), median age 47 years (range 28 - 79) were enrolled in the study. Patients had ITP for a median of 3.5 years and had failed a median of four prior therapies. Splenectomy was not taken into account because contraindicated or refused. All patients received eltrombopag 50 mg by mouth once a day as induction treatment .A complete blood count was performed at baseline, on day 5, then weekly for 28 days, every 2 weeks during maintenance. Complete Response ( CR) was defined as platelet count ≥ 100 * 10^9/L measured on two occasions > 7 days apart and the absence of bleeding. Relapse Free Survival (RFS) was considered to be from the day of initial response until relapse (Plt <30 × 10⁹/L). Treatment safety profiles and side effects were assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0.Maintenance dose of 25 mg every 3 days was initiated in all patients in CR from at least three months.

Results. 7 out of 7 pts achieved CR after eltrombopag induction therapy and were enrolled in the study. 1 out of 7 pts was too early to be evaluated. 6 pts were eligible for the maintenance phase. The median (range) follow-up of this case series was of 13.5 months (4-22), during which all patients maintained a safe platelet count without the need to increase the dose or frequency of administration. No patient relapsed . No adverse events were observed.

Conclusions. Maintenance therapy was manageable and well-tolerated. Maintenance can allow for improved health care resource allocation providing cost savings and potentially improves patients' quality of life by by reducing the need of food restriction/dairy products required when taking eltrombopag.Moreover , maintenance therapy improves adhesion to the treatment and may be an effective alternative for patients who can not discontinue the drug