Abstract
Background Eltrombopag (EPAG) could improve the efficacy of immunosuppressive therapy (IST) consisted by antithymocyte immunoglobulin (ATG) and cyclosporin (CsA) in untreated severe aplastic anemia (SAA) patients. This study explored whether patients with SAA could benefit from continuous use of EPAG beyond 6 months.
Methods From February 2018 to October 2021, 92 Chinese patients who were 2 years of age or older with a new diagnosis of acquired SAA and were not eligible for front-line hematopoietic stem-cell transplantation were collected in the China Eastern Cooperation Group for Anemia (CECGA).
Patients were treated with rabbit ATG (r-ATG) based IST consisting of CsA. Patients over 12 years old and aging 6-11 years old took EPAG orally at dose of 75mg and 37.5mg once daily, respectively; EPAG was administered with 1.25 mg per kilogram per day for patients with age distribution between 2 and 5 years. Generally, all patients were treated with EPAG at least 6 months. The lack of response at 6 months, relapse, HSCT, development of a clonal hematologic disease including myelodysplastic syndrome, and acute myelogenous leukemia, or disease- or treatment-related death are regarded as events in event free survival (EFS).
Results The median age was 38 (2-78) years, with 18 patients (20%) under 18 years old and 21 patients (43%) over 60 years old. In the whole cohort, 61 patients (66%) were diagnosed as SAA and 31 patients (34%) with very severe aplastic anemia (vSAA).
At 3, 6 and 12 months, the actuarial overall response rates (ORR) were 55% (51 of 92), 73% (67 of 92) and 81% (60 of 74) and complete response (CR) rates were 11% (10 of 92), 20% (18 of 92) and 34% (25 of 74), respectively.
18 patients (20%) who achieved CR within 6 months were under steady state. In 49 patients with PR at 6 months, 14 (35%) of 40 patients who were continuously exposed to EPAG improved to CR within 6.5 (3 ~ 10) months of median time after 6 months. Among 25 patients who failed at 6 months, 11 patients continued to use EPAG, and 5 patients (45%) improved responses with extended median time of 3 (1 ~ 6) months after 6 months (Figure 1).
The cumulative effect curve showed that 93% and 58% of all 12 months remission and CR occurred within 6 months. In patients with PR and NR at 6 months, the better 2-year event free survival (EFS) was found in whom continued to use EPAG (75% vs. 26%, P=0.001) (Figure 2).
Discussion EPAG plus IST were used to treat previously untreated SAA patients in prospective studies. The ORR and CR rate at 6 months were 68% ~ 94% and 26% ~ 58%, respectively [1, 2]. We found that 93% of all 12 months remission occurred within 6 months for patients treated with IST and EPAG. It is suggested that EPAG should be used in sufficient dosage at least 6 months.
It has been reported that patients with CR and PR were present with better OS of 100% and 92%, while OS of non-responders was 47% (P=0.0016), effect was demonstrated as a predictor for 4-year OS [3]. For patients with PR and NR at 6 months in our study, it was found that not only the response rates, but also the 2-year EFS were improved by continuous usage of EPAG, compared to them discontinued EPAG.
In conclusion, additional EPAG to IST mainly take effect within 6 months. Continuous administration of EPAG could improve the hematologic response and EFS in patients without achieving CR at 6 months.
REFERENCE [1]. Townsley DM, Scheinberg P, Winkler T, et al., Eltrombopag Added to Standard Immunosuppression for Aplastic Anemia. N Engl J Med, 2017. 376(16): p. 1540-1550.
[2]. Peffault de Latour R, Kulasekararaj A, Iacobelli S, et al., Eltrombopag Added to Immunosuppression in Severe Aplastic Anemia. N Engl J Med, 2022. 386(1):11-23.
[3]. Assi R, Garcia-Manero G, Ravandi F, et al., Addition of Eltrombopag to Immunosuppressive Therapy in Patients with Newly Diagnosed Aplastic Anemia. Cancer, 2018. 124(21):4192-4201.
Disclosures
No relevant conflicts of interest to declare.
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