A recently published study in Platelets has revealed a stable and durable initial response of avatrombopag in adult patients with chronic immune thrombocytopenia (ITP), indicating that patients with an array of background characteristics can experience a durable platelet response with avatrombopag treatment.

Avatrombopag is an oral thrombopoietin receptor agonist (TPO-RA) that stimulates the production of platelet cells and has shown efficacy in treating chronic ITP in adult patients. The drug has no food-type restrictions, making it an attractive option for patients.

The study found that patients who responded well to the medicine maintained their response for most of the time they took avatrombopag. Moreover, most patients did not experience loss of response (LOR) throughout their disease course.

Read more about ITP therapies

The research teamconducted a post-hoc analysis of patients enrolled in a multicenter, parallel, randomized, double-blind group. The phase 3 study evaluated the safety and efficacy of avatrombopag in adult patients with chronic ITP for 6 months. The study consisted of a 6-week drug titration period, a 12-week medication reduction period, and an 8-week maintenance period. All patients were given open-label avatrombopag once daily, with 20 mg as the initial dose, and underwent a 6-week conversion period, followed by a 90-week maintenance period.

The core study phase (total population) had 21 visits over 26 weeks, while the extension phase (total population and by subgroup) had 31 visits over 96 weeks. In the core study phase, 32 patients were enrolled in the avatrombopag group and 17 in the placebo group. In comparison, 39 patients were enrolled in the extension phase, with 24 in the avatrombopag group and 15 in the placebo group.

“To our knowledge, this is the first report to examine the association between these patient characteristics and duration of response to TPO-RA treatment in patients with ITP,” the authors wrote. The study results revealed that patients treated with avatrombopag or placebo during the core study phase and those who received avatrombopag during the extension phase maintained a response for 84.5% and 83.3% of the treatment time, respectively.

In addition, 55.2% of avatrombopag-treated patients in the core study phase never experienced LOR in their core phase, while 52.3% never experienced LOR in both the core and the extension phases. Furthermore, among the patients treated with avatrombopag, older patients were more likely to achieve a response compared to the younger patients (100% versus 82.4%).

“These data suggest that the initial response to avatrombopag is both stable and durable, despite the lower initial dosing in the extension phase,” the researchers noted.


Jain S, Gernsheimer T, Kolodny S, et al.  Additional efficacy analysis of avatrombopag phase III data for the treatment of adults with immune thrombocytopenia, Platelets. Published online April 4, 2023. doi:10.1080/09537104.2023.2195016