A clinical trial has shown eltrombopag, a drug originally designed to stimulate production of platelets from bone marrow, can raise blood cell levels in some people with severe aplastic anemia, who have failed all standard therapies. The findings of the phase 2 trial conducted by the National Heart, Lung, and Blood Institute (NHLBI), and other labs at National Institutes of Health, are published online today in the New England Journal of Medicine; paid subscription required.
In people with aplastic anemia — also known as bone marrow failure — the body fails to make enough red blood cells, white blood cells, and platelets, because of damage to the bone marrow. It is a rare but serious disorder that can develop suddenly or slowly. Aplastic anemia can lead to further cardiac disorders including irregular heartbeats called arrhythmias, enlarged heart, heart failure, infections, and bleeding.
The authors note that about one-third of aplastic anemia cases do not respond to standard therapy, a combination of immune-suppressing drugs. The clinical trial tested the drug eltrombopag, marketed as Promacta by GlaxoSmithKline. The drug had previously been shown to boost platelet levels in healthy people, as well as patients with reduced platelets due to hepatitis C infection or immune thrombocytopenia, a blood disorder that results in low platelet counts and increased risk of bleeding like aplastic anemia.
The results show 11 of the 25 participants enrolled in the study improved production of at least one type of blood cell — red blood cell, white blood cell, or platelet — after 12 weeks of oral eltrombopag therapy. Six of the seven volunteers who continued taking the pills for 8 to 32 months showed an improvement in all three types of blood cells, and were able to maintain safe blood counts without needing red blood cell or platelet transfusions. The researchers report that the drug overall was well tolerated, with few side effects.
The findings showing improvement in red and white blood cell as well as platelet counts in some aplastic anemia patients indicate that the drug can stimulate bone marrow stem cells and have wider utility than its original purpose of platelet production, particularly as a second-line therapeutic option for aplastic anemia.
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