Outcomes, Treatment Patterns, and Resource Use in European Adults with Immune Thrombocytopenia Treated with Avatrombopag

Abstract Objective Clinical trials indicate that avatrombopag, a thrombopoietin-receptor agonist (TPO-RA), is safe and effective for treating patients with primary immune thrombocytopenia (ITP), but real-world evidence on its broader clinical effectiveness is limited. Methods This European multi-center retrospective chart review included adults with primary ITP treated with avatrombopag in routine clinical practice, who had medical records available for ≥ 12 weeks before and after avatrombopag initiation. Results Data from 76 patients with ITP (51 TPO-RA naïve, 25 prior TPO-RA exposed) showed a median time of 4.2 years (interquartile range: 0.7–10.3) from ITP diagnosis to avatrombopag initiation (index date) and a median follow-up of 15.9 months (interquartile range: 7.8–22.8). By week 12, 96 and 93% of the cohort achieved platelet counts (PC) of ≥30 × 109/L and ≥50 × 109/L, respectively; 72% had a complete response (≥100 × 109/L) by week 12, 80% by week 26, and 87% by week 52 postindex. PC reached ≥30 × 109/L, ≥50 × 109/L, and ≥100 × 109/L in a median of 8 (95% confidence interval: 7–12), 10 (8–14), and 19 (12–23) days from the index date, respectively. At 1 year, 75% (n total = 34) and 47% (n total = 21) maintained PC of ≥50 × 109/L and ≥100 × 109/L, respectively. Avatrombopag was permanently discontinued by 19 patients (25%), including 7 (37%) due to being candidates for sustained remission off-treatment. Thromboembolic rates were 4.9 (95% confidence interval: 1.3–12.5) per 100 patient-years during follow-up. The incidence rate (95% confidence interval) of ITP-related outpatient visits and inpatient admissions was 8.9 (8.2–9.5) and 0.1 (0.1–0.2) per person-year. Conclusion This study supports clinical trials’ findings and other postmarketing evidence demonstrating the effectiveness of avatrombopag.