Eltrombopag With Standard Immunosuppression for Severe Aplastic Anemia

Background:

* Severe aplastic anemia is a rare and serious blood disorder. It happens when the immune system starts to attack the bone marrow cells. This causes the bone marrow to stop making red blood cells, platelets, and white blood cells. Standard treatment for this disease is horse-ATG and cyclosporine, which suppress the immune system and stop it from attacking the bone marrow. However, this treatment does not work in all people. Some people still have poor blood cell counts even after treatment.
* Eltrombopag is a drug designed to mimic a protein in the body called thrombopoietin. It helps the body to make more platelets. It may also cause the body to make more red and white blood cells. Studies have shown that eltrombopag may be useful when added to standard treatment for severe aplastic anemia. It may help improve poor blood cell counts.

Objectives:

- To test the safety and effectiveness of adding eltrombopag to standard immunosuppressive therapy for severe aplastic anemia.

Eligibility:

- Individuals at least 2 years of age who have severe aplastic anemia that has not yet been treated.

Design:

* Participants will be screened with a physical exam, medical history, and blood tests. Blood and urine samples will be collected.
* Participants will start treatment with horse-ATG and cyclosporine. Treatment will be given according to the standard of care for the disease.
* Cohort 1: After 14 days, participants will start taking eltrombopag. They will take eltrombopag for up to 6 months.
* Cohort 2: After 14 days, participants will start taking eltrombopag. They will take eltrombopag for up to 3 months.
* Cohort 3 and Extension Cohort: Participants will start taking eltrombopag on Day 1. They will take eltrombopag for up to 6 months.
* Participants may receive other medications to prevent infections during treatment.
* Treatment will be monitored with frequent blood tests. Participants will also fill out questionnaires about their symptoms and their quality of life.