Eltrombopag for Immune Thrombocytopenia in Adult Patients in the Real-World in France. Final Results of the Elextra Study

Introduction:Eltrombopag has been available in Europe for the treatment of chronic primary immune thrombocytopenia (ITP) since 2010. Since 2019, it has been indicated in patients with primary ITP, lasting 6 months or longer from diagnosis and who are refractory to other treatments, aged 1 year and above. However, data are lacking regarding the use, the efficacy and the safety of eltrombopag in clinical practice in Europe. The ELEXTRA study aimed to assess these questions in France. The intermediate results were presented at the 2019 ASH Annual Meeting. We present here the final results of the ELEXTRA study.

Methods:Population source was the CARMEN-France registry. The CARMEN (Cytopénies Auto-immunes : Registre Midi-PyréneEN) registry is aimed at the prospective follow-up of all incident ITP adults in the French Midi-Pyrénées region (South-West of France, 3 million inhabitants) since June 2013. Each investigator follows all adult patients (aged ≥18 years) newly diagnosed with ITP in routine visits or hospital stays, and detailed information on patients' characteristics and management of ITP are prospectively recorded. This registry has been implemented in other French centers since 2016, taking the name of CARMEN-France. ITP was defined by platelet count <100 x 10⁹/L and exclusion of other causes of thrombocytopenia. The study population consisted of all incident ITP adults included in the CARMEN-France registry from June 2013 to December 2019 who were exposed to eltrombopag during the disease course. We described the time from ITP diagnosis to first exposure to eltrombopag, and patients' characteristics. Efficacy was assessed in patients who had a platelet count <30 x 10⁹/L at eltrombopag initiation. Overall response was defined by platelet count ≥30 x 10⁹/L and complete response by platelet count ≥100 x 10⁹/L. Adverse drug reactions (ADRs) that occurred during eltrombopag exposure were collected and assessed according to the World Health Organization causality assessment scale. All ADRs with causality score assessed at least as "possible"were described.

Results:Out of 795 patients included in the registry, 156 (19.6%) had been exposed to eltrombopag for a median duration of 100 days (range: 1-1427). Mean age was 60.2 years (standard deviation: 20.9) and 79 (50.6%) were males; 60 (38.5%) had at least one comorbidity of the Charlson Comorbidity Index score; 89 (57.1%) had at least one cardiovascular risk factor (not including age and sex) and 9 (5.8%) a history of venous thrombosis. At ITP diagnosis, the median platelet count was 8 x 10⁹/L (range: 1-88 x 10⁹/L) and 118 (75.6%) patients had bleeding. Median time from ITP onset to first exposure to eltrombopag was 3.3 months (range: 0.1-82.2): 74 (47.4%) patients were exposed before 3 months of ITP duration, 21 (13.5%) between 3 and 6 months and 61 (39.1%) after 6 months. Exposures to ITP treatments before eltrombopag initiation were: corticosteroids in 150 (96.2%) patients, intravenous immunoglobulin (IVIg) in 106 (67.9%), dapsone in 28 (17.9%), rituximab in 26 (16.7%), romiplostim in 12 (7.7%), hydroxychloroquine in 14 (9.0%), danazol in 8 (5.1%), vinblastine in 5 (3.2%), azathioprine in 2 (1.3%), ciclosporin in 1 (0.6%) and splenectomy in none. Eltrombopag was used as second-line agent in 52 (33.3%) patients and third-line in 56 (35.9%). Among the 156 patients, 75 (48.1%) had a platelet count <30 x 10⁹/L at eltrombopag initiation; among them, 65 (86.7%) achieved overall response and 53 (70.7%) complete response at any time during exposure to eltrombopag. Among the 65 patients who achieved overall response, 58 (89.2%) had a concomitant exposure to another ITP treatment at eltrombopag initiation (including steroids, n=42; IVIg during the past month, n=44; rituximab in the past 6 months, n=11). Overall, 47 ADRs were reported: the most frequent were: thrombocytosis (n=10), thrombosis (n=8: 6 pulmonary embolism, 1 deep and 1 superficial vein thrombosis), rash (n=4), hepatitis (n=3),and headache (n=3).

Conclusion:In French real-world practice, eltrombopag is used early in the ITP course. Efficacy is similar to that observed in clinical trials. The safety profile identified in clinical trials is also confirmed.