Merck’s anti-HIV drug Isentress gets FDA panel’s nod

8 September, 2007

An advisory panel of the United States Food and Drug Administration (FDA) has recommended Isentress, a novel drug against HIV manufactured by Merck and Company, for patients who have developed resistance to other AIDS medicines.

Studies conducted by Merck have shown that Isentress reduces levels of human immunodeficiency virus (HIV) in the blood of patients when other AIDS drugs are no longer effective, the advisers to the FDA have said.

The FDA panel voted unanimously to recommend that the FDA give accelerated approval to the pill for use in combination with other HIV medicines.

Isentress, Merck’s first HIV therapy since 1999, may generate over $1 billion in annual sales, according to analysts.

As many as 40,000 people with AIDS in the United States have limited options for treatment because of drug-resistant HIV, and about three-quarters of patients worldwide have hard-to-treat strains.

Isentress, the first in a new class of AIDS drugs, blocks the process that the HIV virus uses to insert its genetic material into human DNA, allowing replication. The drug targets an enzyme called integrase that HIV uses to accomplish the task.

Studies have shown the medicine helps patients with resistant strains of HIV when used in combination with other drugs.

Merck’s studies found that Isentress reduced the virus to less than the point of detection after four months in 61% to 62% of patients getting the medicine in combination with other anti-HIV drugs. That compares with 33% to 36% of those who got a placebo along with their most effective therapies.

Successful treatment reduces levels of the virus to less than 50 copies per millilitre of blood, which is considered undetectable. The patients came into the studies with at least 1,000 copies per millilitre.

According to Peter Havens, a professor of pediatrics at Medical College of Wisconsin, who voted to recommend approval, “there is no doubt that this is a great drug. It is very useful for patients who have experienced a lot of failure.”

Under the accelerated, six-month review, the FDA is due to decide on approval by the middle of October 2007. Merck and Company, based in Whitehouse Station, New Jersey, the United States, had filed its application on Isentress in April 2007.

The Food and Drug Administration usually follows the recommendations of its advisory panels, though it is not required to do so.

In all, 30 AIDS treatments are approved in the United States, according to the FDA. AIDS patients take the so-called cocktails of anti-HIV drugs each day, typically three or more medicines. The drugs cannot cure HIV, and people with the infections still have the virus in their bodies. Eventually, HIV develops resistance to drugs. Once a drug fails, the combination loses effectiveness.

All HIV drugs are designed to interfere with a part of the HIV lifecycle of infection and replication. HIV attacks and destroys white blood cells, which the immune system uses to ward off invasions from viruses and bacteria.