Treatment opportunities for refractory immune thrombocytopenia

   Background. Primary immune thrombocytopenia (ITP) is an orphan disease characterized by decreased platelet count in the peripheral blood which in some cases can cause bleeding of varying severity. Currently, the use of thrombopoietin receptor agonists (TPO-RAs) is recommended as the second line therapy for ITP as it allows to achieve high platelet response (PR), including complete, in 73 % of cases of chronic ITP and in 87 % of cases of newly diagnosed disease. The mechanism of action differs for different TPO-RAs. Given this fact, in cases of resistance or intolerance to therapy with one TPO-RA, attempts are made to switch to another. The effectiveness of this approach for overcoming ITP resistance varies from 50 to 93 % according to various publications.   Aim. To assess the ability to achieve and maintain PR by switching from one TPO-RA to another in cases of resistance to the previous TPO-RA used in the second or subsequent lines of therapy.   Materials and methods. The analysis included 59 patients who were resistant (in 2 cases intolerance was also noted) to TPO-RA therapy (received after standard therapy) who were prescribed TPO-RA treatment with a different mechanism of action: switch from romiplostim to eltrombopag (25 patients) or vice versa (34 patients). Both groups were comparable in terms of demographic characteristics and median platelet level at the time of TPO-RA switching.   Results. PR was obtained in 76 % of cases, including complete response in 54 %, as a result of switching from one TPO-RA to another in 59 patients. Among 34 patients switched from eltrombopag to romiplostim, PR was achieved in 31 (91 %) patients, including complete response in 22 (65 %). Romiplostim was switched to eltrombopag in 25 patients, PR was achieved in 14 (56 %) with complete response in 10 (40 %).   Conclusion. The study showed that PR can be achieved and maintained through switching from one TPO-RA to an alternative.