The treatment of immune thrombocytopenia (ITP)-focus on thrombopoietin receptor agonists

Abstract

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by increased platelet destruction along with reduced platelet production. All treatments attempt either to reduce the rate of platelet production or increase the rate of platelet production. There is no known cure but most patients attain a hemostatic platelet count. New treatment guidelines have supported a shift from corticosteroids and splenectomy to newer medical treatments that mitigate the thrombocytopenia and avoid splenectomy. The thrombopoietin receptor agonists (TPO-RA), romiplostim, eltrombopag, and avatrombopag, have markedly altered the treatment of ITP. Response rates of 80-90% are routinely obtained and responses are usually maintained with continued therapy. Data shows that TPO-RA are just as effective in early ITP as in chronic ITP and current guidelines encourage their use as early as 3 months into the disease course, sometimes even earlier. TPO-RA do not need to be continued forever; about a third of patients in the first year and about another third after two years have a remission. Whether TPO-RA affect the ITP pathophysiology and directly cause remission remains unclear. This review provides a personal overview of the diagnosis and treatment of ITP with a focus on the mechanism of action of TPO-RA, their place in the treatment algorithm, unique aspects of their clinical use, adverse effects, and options should they fail.