Pb2609: 14 years of experience with thrombopoietin receptor agonists in a single center

Topic: 32. Platelet disorders Background: Immune thrombocytopenia (ITP) is an autoimmune disease characterized by a decreased platelet count (<100 x 10 9/L). Advances in the knowledge of the ITP pathophysiology have allowed the development of different treatments with different therapeutic targets. Thrombopoietin receptor agonists (TPO-RAs), which increase platelet production and have immunomodulatory effects, have shown great efficacy and safety, in clinical trials and in real-life studies. Although they have been approved since 2009 as a chronic/continuous treatment in patients with ITP in second line, some patients may achieve sustained responses. Aims: The aim of our study was to determine TPO-RAs response rate, the response rate after discontinuation and the switch between TPO-RAs in the cohort of patients diagnosed with ITP at Hospital del Mar. Methods: Observational, longitudinal, retrospective and single -center study. All patients with ITP treated with TPO-RAs from June 2008 to April 2022 were included. Demographic data, response to treatment, discontinuation, switch, and relapse were collected. Results: Of a total of 211 patients diagnosed with ITP, 77 patients received TPO-RAs. The characteristics of the patients treated with TPO-RAs, type of TPO-RAs and response achieved are shown in Table 1. Sixty-nine patients (89.7%) achieved a response to TPO-RAs, attempting discontinuation in 47 patients. Of these, TPO-RA was completely discontinued in 20 patients (42.6%), 25.9% of the total series (20/77). However, eight patients (40%) need for retreatment after discontinuation. Figure 1 shows the time until relapse after effective discontinuation. The estimated median to relapse was 39.2 months.Switch between TPO-RAs was performed in 28 of 77 patients treated with TPO-RAs (36.4%). Switch direction: eltrombopag to romiplostim in 19 patients, romiplostim to eltrombopag in 8 patients, and avatrombopag to eltrombopag in 1 patient. Switch reasons: refractoriness or platelet count fluctuations: 16 patients (57.1%); thrombocytosis: 3 patients (10.7%); digestive intolerance: 3 patients (10.7%); patient’s decision: 2 patients (7.1%); liver enzyme alteration: 1 patient (3.6%); headache: 1 patient (3.6%); anaphylactic shock: 1 patient (3.6%). 50% of the patients who underwent the switch due to refractoriness or platelet count fluctuations responded to the other TPO-RAs. Table 1. Characteristics of ITP patients treated with thrombopoietin receptor agonists (TPO-RAs). N=77 - Number of patients (%) Sex ○ Woman○ Man 32 (41.6%)45 (58.4%) Age 71 (21-92) Type of TPO-RA ○ Eltrombopag○ Romiplostim○ Avatrombopag 57 (74%)19 (24.7%)1 (1.3%) Treatment line of TPO-RA ○ 1st line○ 2nd line○ 3rd line○ ≥ 4th line 0 (0%)26 (33.7%)25 (32.5%)26 (33.8%) Response achieved with TPO-RA ○ Complete response○ Partial response○ Refractoriness○ Not evaluated 69 (89.6%)59 (75.3%)7 (9.1%)5 (6.5%)3 (3.9%) Summary/Conclusion: This study shows the experience of 14 years of treatment with TPO-RAs in patients with ITP treated in our center. The percentage of patients in our series who responded to TPO-RAs (89.6%) was similar to figures reported both in the pivotal studies and in other real-life studies. It is important to highlight that only 25% of the patients treated with TPO-RAs were able to discontinue, although the majority reached a long term minimum effective dose. This represents a great benefit both for patients and for health systems, since it improves adherence, possibly also quality of life, and leads to cost savings. More studies are needed to delve into the analysis of the predictive factors of response to TPO-RAs, and, above all, those predictive of discontinuation. Keywords: Idiopathic thombocytopenic purpura (ITP), Immune thrombocytopenia (ITP)