TPO-receptor agonists in ITP: a clinician's navigation between Scylla and Charybdis

Beyond immune thrombocytopenia: the evolving role of thrombopoietin receptor agonists

Since its discovery, the thrombopoietin (TPO) pathway has been an important pharmaceutical target for the treatment of thrombocytopenia. The first generation of TPO mimetics included peptide agents sharing homology with endogenous TPO, but these introduced a risk of antibody formation to endogenous TPO and were not successful. However, second-generation TPO mimetics or TPO receptor agonists (RAs) are currently being used to treat thrombocytopenia associated with a number of conditions, such as immune thrombocytopenia (ITP), severe aplastic anaemia (SAA), and hepatitis C virus-associated chronic liver disease. Accumulating efficacy and safety data suggest that the role of TPO-RAs in the treatment of thrombocytopenia may evolve in the near future with broader use of these agents in ITP and SAA, as well as approval in other indications, potentially including myelodysplastic syndromes, chemotherapy-associated thrombocytopenia, and post-transplant thrombocytopenia. This review provides an overview of clinical data on the efficacy and safety of TPO-RAs, emphasising recent findings that may expand their clinical utility.

The temporary use of thrombopoietin-receptor agonists may induce a prolonged remission in adult chronic immune thrombocytopenia. Results of a French observational study

Thrombopoietin-receptor agonists (Tpo-RAs) are highly effective in immune thrombocytopenia (ITP). Recently, cases of durable remission after Tpo-RA discontinuation in adult ITP have been reported. We aimed to describe the subset of patients in whom transient Tpo-RA therapy may induce a durable response. We studied all adults with primary ITP treated with at least one Tpo-RA over a 5-year period (n = 54) and seen at one of three participating referral centres in France. Tpo-RAs were discontinued in 20 of 28 patients who achieved a complete response. We excluded six patients because a previous treatment at the start of Tpo-RA treatment may have interfered with the response. Overall, eight patients with chronic ITP showed a sustained response [median follow-up: 13·5 months (range 5-27 months)]. We could not identify a predictive factor of sustained response. In conclusion, a substantial proportion of ITP patients receiving Tpo-RAs can maintain a durable response after treatment discontinuation.