Glaxo Says Promacta for Hepatitis C Cured Patients in Trial

GlaxoSmithKline Plc said its Promacta blood disorder medicine eradicated hepatitis C in 23 percent of patients in a clinical trial.

Patients who took a placebo in the study of Promacta, known scientifically as eltombopag, had a cure rate of 14 percent, a statistically significant difference, Glaxo said today in a statement. Results from the study of 716 adults, called Enable 1 and part of the last of three stages of clinical testing usually required for regulatory approval, were presented at the American Association for the Study of Liver Diseases’ annual Liver Meeting in San Francisco.

The medicine, already approved for sale in the U.S. to raise platelet counts in patients with a rare blood disorder, is being studied in patients with thrombocytopenia, a blood complication stemming from hepatitis C treatments. The product may generate as much as $2 billion in additional annual sales if the U.K.’s largest drugmaker can win approval for that use, according to UBS AG.

As many as 170 million people worldwide are chronically infected with the hepatitis C virus, which can lead to cirrhosis of the liver and liver cancer, according to the World Health Organization. Glaxo’s Promacta would enable hepatitis C patients to be treated with antiviral medicines for longer periods of time, turning the drug into a “potential blockbuster,” said Gbola Amusa, an analyst at UBS in London, in an interview before the results were released.

Promacta had sales of 51 million pounds ($82 million) this year through the end of September, compared with 31 million pounds in all of 2010.

Sales Estimate

If the data are positive, an approval by regulators may come as early as the end of next year, Amusa said. The sales estimate assumes that antiviral medicines including interferon will continue to dominate hepatitis C treatments, Amusa said. Abbott Laboratories last month presented interim study results for a new alternative therapy that doesn’t use interferon.

“Undoubtedly, this would be a big potential opportunity for the drug if it demonstrates strong results,” Gustav Ando, a health-care analyst at consulting company IHS Global Insight in London, said before the results were released. “We remain somewhat cautious until we see some of the side-effects data.”

Any potential damage to the liver in terms of toxicity along with blood clotting are of concern, Amusa and Ando said.

Side Effects

In the study released today, serious side effects occurred in 20 percent of the patients in the Promacta group, compared with 15 percent taking a placebo. Worsening of liver function was reported by 13 percent of the patients on Promacta, versus 8 percent of placebo patients, Glaxo’s statement said.

Initial data from a second study with 805 patients showed a 19 percent cure rate compared with 13 percent in the placebo group, Glaxo said in its statement. Adverse events were reported in 20 percent of the patients taking Promacta in the study, called Enable 2, while 15 percent of the placebo patients reporting serious side effects. The company said it would report the complete data at a future medical meeting.

Glaxo said on Oct. 26 it planned to file as many as 10 drugs for approval next year. The compounds in late-stage development include Relovair, which Glaxo is developing as a successor to the Advair asthma inhaler. Advair, Glaxo’s best-selling product, generated 19 percent of total revenue in the first half of the year.

Three Glaxo products have been cleared for sale this year, including Benlysta, a therapy for the auto-immune disease lupus that was approved by U.S. regulators in March. The company’s global sales in the quarter ended Sept. 30 rose 4.3 percent to 7.1 billion pounds from a year earlier.

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