Thrombotic Complications in Immune Thrombocytopenia Patients Treated with Avatrombopag.

Avatrombopag is a novel oral non-peptide thrombopoietin receptor agonist (TPO-RA) that was approved by the FDA as a second-line therapy for chronic immune thrombocytopenia (cITP). Avatrombopag has shown promising results in regards to efficacy and tolerability, but to our knowledge, there are no reports of thrombotic complications associated with avatrombopag. We present two patients with chronic ITP who suffered thromboembolic events shortly after starting treatment with avatrombopag. The first case is that of a 30-year-old female with refractory cITP who failed multiple lines of ITP therapy and was hospitalized with an intracranial bleed. The patient eventually recovered after an emergent splenectomy but subsequently developed a right lower lobe pulmonary embolism three weeks after starting treatment with avatrombopag. The second case is that of a 58-year-old female with a prolonged history of ITP, and no prior history of peripheral vascular disease, who suffered from both arterial and venous thrombotic events four weeks after starting avatrombopag. Given the new arterial and venous thrombotic complications, avatrombopag was stopped. She was challenged with avatrombopag again and developed yet another thrombotic complication.