Real-World Effectiveness and Safety of Eltrombopag in Patients with Aplastic Anemia: A Chinese Nationwide Survey

Immunosuppressive therapy (IST) based on antithymoglobin (ATG) and cyclosporin (CsA) is the first-line treatment for severe aplastic anemia (SAA) patients who are unfit for transplantation,and the overall response rate (ORR) is about 70%.The utility of eltrombopag (EPAG),a TPO receptor agonist, achieved robust hematologic response in refractory and treatment-naïve SAA patients in clinical trials and some other studies. However, only a few data came from Asia countries where higher incidence of AA has been reported.

A retrospective study on the use of EPAG in AA was conducted in mainland China. Aplastic anemia (transfusion dependent non-severe, severe, and very severe) patients who started eltrombopag before Feb 2019 and continued for at least 3 months either as first-line treatment or as rescue treatment, were enrolled. The maximum daily dosage of EPAG used continuously for at least 2 weeks is defined as the stable dosage. Response criteria were referred to that used in previous reports (Townsley DM, NEJM 2017; BCSH, BJH 2016).

Fifty-six patients from eleven centers were enrolled in this study, including 26 males and 30 females at the median age of 39 (7-80) years. All patients were transfusion-dependent by the time of EPAG administration, and there were 14 VSAA, 24 SAA and 18 transfusion dependent non-severe aplastic anemia (TD-NSAA). Nineteen treatment-naïve patients received EPAG and IST (ATG+CsA, n=10; CsA/CsA+androgen, n=9) as first-line treatment. Thirty-seven patients were refractory to IST. Eltrombopag was administered at a median dose of 75 (25-150) mg per day for 7 (3-31) month. The median follow-up time was 9 (3-40) months.

The overall response rate in patients receiving EPAG as first-line therapy was 78.9% (15/19), and most patients achieved complete response (CR) (10/15). Among the 10 patients receiving ATG+CsA, 6 patients achieved hematologic response (HR) at 3 months post-treatment, including 3 CR. Six patients were diagnosed as VSAA and three achieved HR. For the 9 patients treated with CsA/CsA+androgen, 8 achieved HR (88.9%) and 4 were CR (44.4%) at 3 months. By last follow-up, the cumulative HR rate was 70% in ATG+CsA group and 89% in CsA/CsA+ androgen group. Among the 14 responders, 11 patients receiving EPAG at a stable dosage ≤75mg/d and achieved HR at 3 months.

The overall response rate in IST-refractory patients was 46% (17/37), with trilineage response in 27% patients at 3 months. For the 18 ATG+CsA refractory SAA patients,trilineage HR occurred in 4 patients (22.2%, 4/18), bi-lineage HR in one patient and single lineage HR in one patient. Thus, the total HR was 33.3% (6/18) at 3 months and increased to 44% (8/18) by last follow-up. Among the 19 CsA/CsA+ androgen refractory patients, 6 (31.5%, 6/19) achieved trilineage HR, one achieved bi-lineage HR and 4 achieved single lineage response. Total HR rate was 57.9% (11/19) at 3 months after EPAG initiation and 68% (13/19) by last follow-up, including 9 patients with trilineage HR. Among 17 responders, 13 received a stable EPAG dose of≤75mg/d.

Most patients tolerated EPAG well. Adverse events occurred in 29 patients (52%) and most were mild to moderate, including gastrointestinal symptom (n=15, e.g. abdominal pain, nausea), impaired liver function (n=5), skin changes (n=7, e.g. skin pruritus and rash) and musculoskeletal pain (n=6), and venous thrombus (n=2). Eltrombopag dosage was reduced in 2 patients due to severe digestive symptoms at 100 mg/d and discontinued in one patient who suffered from upper limb venous thrombus.

In conclusion, EPAG is effective and safe in treating Chinese AA patients at a daily dose of 75mg and less. The real-world result of EPAG in Chinese patients is similar to those reported in Western countries.