Avatrombopag/Sulcosin Treatment Increases Platelet Counts in Adults with Chronic Immune Thrombocytopenia

A Phase 3 study of avatrombopag/sucocin (Avatrombopag) in adults with chronic immune thrombocytopenia (ITP) met its primary endpoint. The resultshave been published. The open-label, phase 3 AVA-ITP-307 study (ClinicalTrials.gov identifier: NCT05369208) enrolled adult patients with chronic ITP at centers across Japan. Eligible patients were required to have an inadequate response to previous ITP treatment and an average of 2 platelet counts below 30x10^9/L.

The initial dose of avatropopag is20 mg/d. The core phase of the study is 26 weeks, which includes a 4-week dose titration period to a maximum dose of 40 mg/day. A concomitant ITP drug reduction period also occurred during the core phase and was adjusted for platelet count. The expansion phase following the core phase is currently underway. The primary endpoint of the study is the cumulative number of weeks with a platelet count of at least 50xx10^9/L without rescue therapy. The study also had a key secondary endpoint, platelet response at day 8, based on the percentage of patients with a platelet count of at least 50xx10^9/L who did not receive rescue therapy.

There19 patients participated in the 26-week core period, and their average age was 56.0 years. The majority (78.9%) of patients were female. A total of 15 patients completed the core phase, and all of these patients participated in the expansion phase. In the primary endpoint analysis, patients had a mean cumulative number of weeks of platelet response of 13.5 weeks (95% CI, 9.1-17.8). The primary endpoint was met based on the results exceeding the target statistical threshold.

For the key secondary endpoint,63.2% (95% CI, 38.4-83.7) of patients demonstrated a platelet response at day 8. Additionally, 42.1% (95% CI, 20.3-66.5) of patients were found to achieve durable platelet responses. It is characterized by a platelet count of at least 50xx10^9/L in 6 out of 8 weeks during the last 8 weeks of treatment in the core phase.

Treatment-emergent adverse events (TEAEs) were reported in 94.7% of patients during the core period, of which 15.8% had TEAEs thought to be related to avatimbopag. Serious adverse events were reported by 15.8% of patients, and grade 3 or higher TEAEs were reported by 15.8%. No thromboembolic events or deaths were reported during the core phase.

The researchers wrote in their report: "These data add to the evidence supporting the use of avilobopag to treat primary chronic ITP in diverse populations, including those of different races, and highlight that no different or adjusted doses are needed in the Japanese population compared with previously studied populations."

Reference materials:https://go.drugbank.com/drugs/DB11995