Background Primary immune thrombocytopenia (ITP) is a disorder that is characterised by immune-mediated platelet destruction and impaired platelet production.

Purpose To evaluate the effectiveness of eltrombopag, the first oral thrombopoietin receptor agonist in the treatment of ITP.

Materials and methods The authors report the cases of four patients (patients 1-4) with ITP refractory to first-line treatment (glucocorticoids and immunoglobulin) who were treated with eltrombopag to achieve platelet counts of at least 50x10⁹/l (threshold count, TC). Data were obtained from clinical histories and laboratory tests. Parameters evaluated: previous treatments, platelet counts before eltrombopag, platelet response (achievement of TC), length of treatment to achieve TC and period of study.

Results The four patients (2 men and 2 women, mean age 67±19) had been refractory to first-line treatment. Patient 4 had also been refractory to splenectomy, rituximab, dapsone and azathioprine, and had been treated with romiplostim, which was not well tolerated. Patient 1 started treatment with 11x10⁹/l platelets, patient 2 with 34 x10⁹/l, patient 3 with 19 x10⁹/l and patient 4 with 9 x10⁹/l. After a period of 6 weeks (patient 1), 3 weeks (patients 2 and 3) and 1 day (patient 4) of treatment with 50 mg of eltrombopag once daily (combined with 2 doses of 40 g of immunoglobulin at the beginning of the treatment in patient 4) they all achieved platelet counts above the TC and have maintained them. The total period of study was 28 weeks (patient 1), 15 weeks (patients 2 and 3) and 10 weeks (patient 4). No adverse effects were reported. All the patients are still receiving eltrombopag.

Conclusions Our results agree with those of clinical studies that show that eltrombopag could be an effective and safe treatment for ITP patients who are refractory to other treatments. Nevertheless, further studies should be carried out to evaluate long term safety and efficacy.