The U.S. Food and Drug Administration (FDA) has approved a new indication for eltrombopag (Promacta?/Revolade?; GSK/GlaxoSmithKline), a thrombopoietin receptor agonist. The new indication approves eltrombopagfor the treatment of thrombocytopenia (low blood platelet counts) in patients with chronic hepatitis C to allow them to initiate and maintain interferon-based therapy.
Approximately 4.2 million people in the US have chronic hepatitis C, the most common blood-borne virus. It is estimated that up to 3.5% of these patients have platelet counts <75,000/?L, which could make them ineligible to start or maintain their interferon-based therapy.
Eltrombopag is the first supportive care treatment available to patients who are ineligible or poor candidates for interferon-based therapy due to their low blood platelet counts. The drug, in combination with interferon-based therapy, has been shown to improve a patient?s chance of achieving a sustained virologic response (SVR) or viral cure.
Treatment limitation
There are limitations to the use of eltrombopag in patients suffering from chronic hepatitis C-associated thrombocytopenia. Eltrombopag:
– should not be used in an attempt to normalize platelet counts;
– should be used only in patients with chronic hepatitis C whose degree of thrombocytopenia prevents the initiation of interferon therapy or limits the ability to maintain optimal interferon-based therapy; and
– Safety and efficacy have not been established in combination with direct-acting antiviral agents approved for treatment of chronic hepatitis C genotype 1 infection.
Low platelet challenge
?Chronic hepatitis C is a significant public health issue,? said Paolo Paoletti, M.D., President, GlaxoSmithKline Oncology. ?Some chronic hepatitis C patients suffer from low blood platelet counts. Commonly prescribed interferon-based therapies can worsen the problem of low blood platelet counts. Today?s FDA approval of PROMACTA gives doctors a tool to address the low platelet challenge. This means more chronic hepatitis C patients may be able to start and stay on interferon-based therapy. That gives these patients a better chance to achieve a viral cure.?
The approval for eltrombopag is based on results from ENABLE 1 and 2 (Eltrombopag to INitiate and Maintain Interferon Antiviral Treatment to Benefit Subjects with Hepatitis C related Liver DiseasE), two Phase III randomized, double-blind, placebo-controlled, multicenter studies, which collectively enrolled 1,521 patients with platelet counts <75,000/?L. ENABLE 1 utilized peginterferon alfa-2a (PEGASYS?) plus ribavirin for antiviral treatment and ENABLE 2 utilized peginterferon alfa-2b (PEGINTRON?) plus ribavirin.
Adverse Reactions
The most common adverse reactions in 2 randomized placebo-controlled clinical trials in thrombocytopenic patients with chronic hepatitis C (?10% and greater than placebo) for PROMACTA versus placebo were: anemia (40% vs. 35%), pyrexia (30% vs. 24%), fatigue (28% vs. 23%), headache (21% vs. 20%), nausea (19% vs. 14%), diarrhea (19% vs. 11%), decreased appetite (18% vs. 14%), influenza?like illness (18% vs. 16%), asthenia (16% vs. 13%), insomnia (16 % vs. 15%), cough (15% vs. 12%), pruritus (15% vs. 13%), chills (14% vs. 9%), myalgia (12% vs. 10%), alopecia (10% vs. 6%), and peripheral edema (10% vs. 5%).
Eltrombopag, marketed under the brand names Promacta? in the U.S. and Revolade? in Europe and Rest-of-World. In the United States, eltrombopag is already indicated for the treatment of thrombocytopenia in patients with chronic ITP who have had an insufficient response to corticosteroids, immunoglobulins or splenectomy.
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