Eltrombopag may be useful in secondary ITP patients in clinical practice

Background: Eltrombopag is a thrombopoietin receptor agonist (TPO-RA) approved for treating chronic primary ITP patients. Nevertheless, due to the non-existence of clinical trials there are no clear efficacy and safety data of eltrombopag in secondary ITP. Aims: To evaluate the efficacy and safety results using eltrombopag for treating secondary ITP patients in routine clinical practice in Spain. Methods: 33 secondary ITP patients from 23 Spanish centers who had been treated with eltrombopag and included in the Spanish Eltrombopag ITP Registry were retrospectively evaluated. However, 5 patients were excluded from the final analysis because three of them were aplastic anaemias, one was an amegakaryocytic thrombocytopenia and another one was a acute myeloid leukemia related thrombocytopenia. Results: Our secondary ITP case series included nine hepatitis C virus-ITP, five lymphoproliferative disorders, four systemic lupus erythematosus (SLE), three HIV-ITP, two synchronous HCV-HIV-ITP, two psoriatic arthritis, one Evans Syndrome, one common variable immunodeficiency and one Sjögren syndrome. The median age of our cohort was 54 (IQR, 35-66) years. There were 17 women and 11 men. 25% of patients had a Charlson Comorbidity Index score of 2 or more at diagnosis. The median time from secondary ITP diagnosis to eltrombopag initiation was 36 (IQR, 1-76) months. The median number of therapies before starting eltrombopag was 2 (IQR, 1-4), including rituximab (28%), romiplostim (17%) and splenectomy (10%). At the time of treatment start, 15 of 28 patients (53%) patients were receiving concomitant treatment for secondary ITP, mainly including corticosteroids (31%) or immunoglobulins (21%). 7 of 28 (25%) patients had bleeding symptomatology during the month preceeding the starting eltrombopag. At eltrombopag initiation the median platelet count was 9x109/L (IQR, 6-15x109/L). 25 of 28 (89%) patients responded to eltrombopag treatment. 23 patients (82%) achieved a complete response (CR; platelet count >100x109/L). To point out that 2 patients needed concomitant treatment with low prednisone doses to achieve or maintain the response. It was a slight difference between men and women regarding the response and complete response rates obtained: men achieved 82% and 73% respectively meanwhile women achieved 94% and 83%. The proportion of patients achieving platelet response was quite similar regardless the other studied parameters: age (87% and 92% for patients <65 years-old and ≥65 years-old, respectively), use of concomitant ITP medication at baseline (87% and 93% for patients with and without concomitant baseline ITP medication use) and bleeding at starting eltrombopag (100% and 87% for patients with and without bleeding, respectively). Three patients achieved complete response after only one month of tretament without relapsing afterwards. In five patients splenectomy was made few months after eltrombopag treatment (3 patients were in CR). Only two patients failed to achieve response with eltrombopag treatment: common variable immunodeficiency and one HIV patients. After a 9 months median follow-up, 15 patients maintain the response. Only 3 patients relapsed from their disease. Only two adverse events were reported: a grade 2-3 cephalea in a SLE patient and a death caused by respiratory insufficiency in a HIV patient with a CR ITP at that moment. Summary and Conclusions: Our case series describe the great efficacy and safety results observed with the use of eltrombopag in our secondary ITP patients. Our data suggest some diseases may not benefit from the use of eltrombopag. However more studies are needed to confirm the possible usefulness of TPO-RAs in this variety of secondary ITP cases.