Merck & Co.'s Isentress treatment for HIV showed positive results in combination therapy across diverse groups of patients, the U.S. pharmaceutical giant said Monday.

The study results were presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago.

Merck reported the results of a study of 209 adults who received the treatment twice a day in combination therapy for up to 48 weeks.

The report followed a study of a once-daily dose of Isentress last year that showed Isentress was not as effective as the standard twice-daily regimen.

The U.S. Food and Drug Administration approved Isentress in 2007 as the first of a new class of HIV drugs, known as HIV integrase inhibitors, which work by interfering with the virus' ability to replicate itself.

Merck and other pharmaceutical companies were striving to replace blockbuster drugs that are coming off patent protection.

The company reported in July that its second-quarter earnings soared on a $1.34 billion tax benefit and other items. At the time, Merck also reported strong sales growth of key drugs, but said it plans to cut another 12,000 to 13,000 positions by the end of 2015.

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