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

Abstract

Predominantly antibody deficiencies have an estimated prevalence of >1 in 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 for infections and considering nonimmunosuppressive treatments, such as thrombopoietin receptor agonists (TPO-RAs), are important considerations for these patients. This nationwide retrospective case series assessed the 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 × 109/L and 100 × 109/L, respectively. We analyzed data from 28 patients. The median follow-up time after introduction of the first TPO-RAs was 33 months (range, 2 weeks to 10.6 years). After 6 weeks of follow-up, response was achieved in 24 of the 28 patients (85.7%), and among those, 21 patients (75%) displayed a complete response. At the last available follow-up visit, only 7 patients (25%) needed second-line therapies for ITP, and among those, only 5 patients (17.9%) received immunosuppressants. Only 3 patients (10.7%) reported laboratory-confirmed hepatobiliary adverse events of light or mild severity and 3 patients (10.7%) reported thrombotic events. In conclusion, TPO-RAs seemed to be 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 for ITP related to predominantly antibody deficiencies.