Efficacy and safety of TPO receptor agonists in treatment of ITP associated with predominantly antibody deficiencies

• After 6 weeks of treatment, response was achieved for 24 out of 28 patients (85.7%)

• Thrombotic events were reported for 3 patients (10.7%), none of which exhibited bleeding complications

Predominantly antibody deficiencies have an estimated prevalence of more than 1/25,000. Their classical phenotype entails the association of autoimmune manifestations with increased susceptibility to infections. Up to 8% of these patients ultimately develop immune thrombocytopenic purpura (ITP). Reducing the risk of infections and considering non immunosuppressive treatments, such as thrombopoietin receptor agonists (TPO-RAs), are important needs in these patients. This nationwide retrospective case series assessed outcomes and safety of TPO-RAs as treatment for ITP in adults diagnosed with predominantly antibody deficiencies. Response and complete response to treatment were defined as platelet count reaching 30 x 109/L and 100 x 109/L respectively. We analyzed data from 28 patients. The median follow-up after introduction of the first TPO-RAs was 33 months (range, 2 weeks - 10,6 years). After 6 weeks of follow up, response was achieved for 24 out of 28 patients (85.7%), among which 21 patients (75%) displayed a complete response. At the last available follow-up visit only 7 patients (25%) needed second-line therapies for ITP among which only 5 patients (17.9%) received immunosuppressants. Only 3 patients (10.7%) reported hepatobiliary laboratory adverse events of light or mild severity and 3 patients (10.7%) reported thrombotic events. In conclusion, TPO-RAs appeared as an effective and safe option of treatment in these case series. Our results suggest that Eltrombopag or Romiplostim should be considered as second line therapy of ITP related to predominantly antibody deficiencies.