Research: Merck AIDS drug as effective as Abbott pills

Merck & Co.'s Isentress tablets suppressed HIV as successfully as older drugs by Abbott Laboratories and Gilead Sciences Inc., according to research that may spur sales.

Patients who started treatment with Isentress fared as well as those given Gilead's Truvada when the products were combined with Abbott's Kaletra, scientists said today at the International AIDS Conference in Vienna. A separate study, contradicting earlier research, found that switching to Isentress from Kaletra or similar drugs was as effective for patients, with less of the cholesterol-related side effect.

Doctors are searching for safer alternatives to the older generation of AIDS treatments, which includes Kaletra and Truvada, as patients live longer, said Esteban Martinez, the lead researcher on the study comparing Isentress and Kaletra. Doctors may become more inclined to prescribe Isentress as a result of the research, he said.

"Patients are now living longer and while viral suppression is still a concern, for many patients the major concern is the long-term effects and premature aging related to the drugs," said Martinez, an associate professor of medicine at the University of Barcelona in Spain.

Merck fell 1 cent to $35.90 at 11:10 a.m. in New York Stock Exchange composite trading. Abbott rose 44 cents to $47.51. Gilead rose 84 cents, or 2.6 percent, to $32.78 in Nasdaq Stock Market composite trading.

33 Million PeopleHIV is the virus that causes AIDS. That condition afflicted an estimated 33 million people worldwide as of July 2008, according to UNAIDS. Gilead, based in Foster City, California, is the world's largest maker of AIDS drugs.Kaletra and other protease inhibitors have been linked to an increase in cholesterol, which can lead to heart attacks, and Viread, a component of Truvada, may cause kidney damage or bone loss, according to the drugs' prescribing information.Merck, the second-largest U.S. drugmaker after Pfizer Inc., began selling Isentress in 2007. The product generated $752 million in sales last year. It is the first in a class of drugs that attacks the virus in a unique way by blocking integrase, a protein used by HIV to hijack healthy immune cells. The result is to slow the spread of HIV in the body.$1.4 BillionKaletra, which had $1.4 billion in revenue for Abbott, prevents the virus from replicating by blocking proteases. Truvada combines the drugs Viread and Emtriva to stop the HIV virus from multiplying. Truvada, with $2.49 billion in sales, was the top product last year for Gilead, accounting for 38 percent of total sales.In the study comparing Isentress and Truvada used in combination with Abbott's Kalentra, researchers tracked 206 patients who hadn't taken any other treatment for their virus. Among patients taking Isentress, 83 percent had their virus at undetectable levels at 48 weeks, compared with 85 percent of those on Truvada.Abbott, which funded the study, is waiting for longer-term data before making a determination about which combination -- Isentress and Kaletra or Truvada with Kaletra -- poses fewer side effects, said Scott Brun, a vice president for the infectious disease development division at the Libertyville Township-based company.Combination PillAbbott will consider whether to develop a combination pill of Isentress and Kaletra once it has results from 96 weeks of treatment, Brun said.The study that looked at switching patients to Isentress from Kaletra was funded by the Hospital Clinic of Barcelona. The study covered, over 48 weeks, almost 300 patients whose disease was well controlled on Kaletra and a combination of other AIDS drugs.The researchers found that 89 percent of patients who moved to Isentress had their virus controlled, a sign of successful treatment, compared with 87 percent who continued taking Kaletra.Patients taking Isentress had lower cholesterol after 48 weeks than those who continued taking Kaletra, according to the report. Safety data from the study comparing Isentress and Truvada weren't available.A separate study, funded by Whitehouse Station, New Jersey- based Merck and released last year, found that AIDS patients who switched to Isentress from Kaletra were more likely to have a relapse. That finding, which involved about 700 patients, prompted Merck to stop studies that looked at switching between the drugs.