Pb2618: use and discontinuation of thrombopoietin receptor agonists in patients with immune thrombocytopenia: a single centre experience

Topic: 32. Platelet disorders Background: Thrombopoietin receptor agonists (TPO-RAs) usage appears to be effective for the treatment of primary immune thrombocytopenia (ITP). Their administration as a second-line maintenance therapy has been extended in recent years with a better safety profile compared to splenectomy, maintaining high rates of platelet response. There is an increasing interest in the discontinuation of TPO-RAs in patients with ITP. However, there is insufficient evidence to standardize their suspension. Aims: We aimed to assess the use and efficacy of TPO-RAs and to provide information about the outcome of treatment discontinuation. Methods: This is a retrospective, single-centre, descriptive study of patients diagnosed with ITP in our centre between 2010 and 2022 who received treatment with TPO-RAs. Demographic data was collected, response rates and discontinuation were evaluated. Response was defined as an increase in platelet count over 30x109/L with at least a two-fold from the baseline, complete response was considered when platelet count was over 100x109/L at any time of evaluation and sustained complete response when rates were greater than 100x109/L at 12 months. Discontinuation of treatment was evaluated with a review of platelet counts during 2 years after suspension. All statistical tests were performed with the IBM SPSS Statistics v. 26.0. Quantitative variables are expressed through variables of central tendency, median, and interquartile range, and proportions through the Chi-square test. Results: A population of 96 patients was analyzed, 35 in the romiplostim subgroup and 61 in eltrombopag. The median age at diagnosis was 52 (34-69) years; 58,3% (n=56) were females while 41,7% (n=40) were males. The median time from diagnosis to start TPO-RAs was 15 (1-72) months and the median time of the duration of treatment was 11 (2-31) months. All patients had received prior therapy. The median of lines of treatment received previously was 2 (1-3) in the whole group. Regarding the subgroups, 3 (2-4) previous lines where administered in the romiplostim cohort while 2 (1-2) lines were prescribed in the eltrombopag group. A 28,6% (n=10) and 8, 2% (n=5) respectively had undergone previous splenectomy. The indication for TPO-RA therapy was as maintenance therapy in 88,57% (n=31) in the romiplostim group; 93,44% (n=57) in the eltrombopag group while 11, 43% (n=4) and 6.55% (n=4) were prescribed prior to surgery, respectively. Response was obtained in 97,1% (n=34) in the romiplostim cohort and 88,9% (n=48) in the eltrombopag subgroup with no significant difference between both groups (p=0,350). Complete response was achieved in 85,7% (n=18) in the romiplostin´s and in 70,2% (n=33) in eltrombopag, no significant difference was observed (p=0,794). Sustained complete response was reached in 64,3% (n=18) and 70,2% (n=33) in the romiplostim and the eltrombopag subgroup respectively with no significant difference between groups (p=0.68) (Image A) Treatment could be discontinued in 25, 7% (n=9) and 21.3% (n=13) in the romiplostim and the eltrombopag cohort, respectively, with no significant differences between groups (p=0.668), maintaining platelet counts over 50x109/L during two-year monitoring (Image B).Summary/Conclusion: TPO-RAs have high response rates. There was no difference between TPO-RAs. Discontinuation may be a safe strategy with long-term response. This evidence could provide, therefore, a change in the natural history of the disease with fewer episodes of bleeding without active treatment. Keywords: Thrombopoietin (TPO)