Ligand, GlaxoSmithKline drug eltrombopag ups platelet count, study shows

By Angela McDaniels

Seattle, Dec. 2 - Ligand Pharmaceuticals Inc. said eltrombopag, a drug developed through collaboration with GlaxoSmithKline, increased platelet counts in 115 patients with chronic idiopathic thrombocytopenia purpura in a phase 2 clinical trial.

Patients had failed at least one prior therapy and had platelet counts of less than 30,000 at the outset of the study, the company said.

In the phase 2, dose-ranging clinical study conducted by GlaxoSmithKline, 66% of patients receiving 50 mg of eltrombopag per day and 87% of patients treated with 75 mg per day had counts greater than or equal to 50,000 platelets after six weeks, and many of those had reached normal platelet levels within the first two to three weeks of treatment.

In comparison, only 13% of placebo-treated patients showed platelet increases greater than or equal to 50,000 after six weeks, the company said.

The frequency of side effects was comparable between patients treated with placebo and those treated with eltrombopag. Additional clinical data shows encouraging results in an interim analysis in a phase 2 study of the drug in hepatitis C patients, the company said.

Ligand received a $1 million milestone payment from GlaxoSmithKline when the company began phase 2 trials for eltrombopag in February 2005 and a milestone of $2 million in June for the initiation of phase 1 development of a SB-559448, another platelet-boosting drug covered by the collaboration agreement.

If the drugs continue in development and are ultimately approved and marketed, Ligand could receive additional milestone payments and royalties on net product sales of 5% to 10%.

Eltrombopag is a small-molecule drug that mimics the activity of thrombopoietin, a protein factor that promotes growth and production of blood platelets. It is indicated for idiopathic thrombocytopenia purpura, hepatitis C and chemotherapy-induced thrombocytopenia.

Thrombocytopenia - decreased platelet count - is a common side effect of many chemotherapies and can lead to uncontrolled bleeding, the company said.

The emerging thrombopoietin global market could be between $2.5 billion and $4.5 billion per year, the company said.

Ligand is based in San Diego, Calif., and develops drugs to address critical unmet medical needs of patients in the areas of cancer, pain, skin diseases, men's and women's hormone-related diseases, osteoporosis, metabolic disorders and cardiovascular and inflammatory diseases.

GlaxoSmithKline is a pharmaceutical company with U.S. operations in Philadelphia and Research Triangle Park, N.C.

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