Catastrophic antiphospholipid syndrome in an immune thrombocytopenia patient treated with avatrombopag

Background: Avatrombopag is an orally administered second-generation thrombopoietin receptor agonist (TPO-RA) approved for the treatment of chronic immune thrombocytopenia (ITP). However, increased thrombogenicity in patients with ITP after initiation of TPO-RA treatment has been reported.Key Clinical Question: We report a case of a patient with ITP who developed a catastrophic antiphospholipid antibody syndrome (CAPS), following treatment with avatrombopag.Clinical Approach: A 20-year-old known chronic patient with ITP presented at the emergency department with a 2-week history of headache, nausea, and abdominal pain, 3 weeks after initiating avatrombopag. In-hospital diagnostic work-up revealed multiple microvascular thrombotic events, including myocardial, cerebrovascular, and pulmonary infarctions. Laboratory test results showed a triple-positive antiphospholipid antibodies serology. Conclusion: The diagnosis of probable avatrombopag-associated CAPS was made.