Great News

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http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2007/10/13/MN4VSP4RQ.DTL


San Francisco Chronicle

FDA approves important new AIDS drug Isentress

- Sabin Russell,
Chronicle Medical Writer
Saturday, October 13, 2007

Pharmaceutical giant Merck & Co. won Food and Drug Administration approval Friday for Isentress, an HIV suppressor that has performed well in clinical trials and has been hailed as the most important new AIDS drug in a decade.

The Merck drug has been closely watched since human testing began in 2005 because it was the first AIDS medicine to block an enzyme, called integrase, that is crucial in the process HIV uses to replicate.

The new medication, also known by its generic name, raltegravir, is the first of what is expected to be a new class of AIDS drugs known as integrase inhibitors.

Two other enzymes, reverse transcriptase and protease, are the targets of almost all other major AIDS drugs. These drugs work better in combination than by themselves. Now, doctors have a pill that attacks the third in this trio of critical enzymes, and clinical trials have shown Isentress to be particularly beneficial in these drug combinations.

"This is fantastic news," said UCSF Professor Dr. Warner Greene, director of the Gladstone Institute of Virology and Immunology. "This drug looks more potent than virtually anything we have ever seen."

First to benefit from the new medication are thousands of people who have been infected for years and have grown resistant to so many AIDS drugs that they are running out of options.

This is the group that was used to test the new drug in clinical trials. More than 80 percent of those who took Isentress saw the level of virus in their blood drop to barely detectable levels - a sign that the disease is under control.

"We are at a watershed period for these patients. For many years, they have had a limited number of options," said Dr. Robin Isaacs, leader of Merck's HIV treatment and vaccine efforts.

Patients who are prescribed the drug will take two 400 mg tablets a day, in combination with other AIDS medicines chosen by their physicians.

Isentress is the latest of several AIDS drugs to be approved this year that, in combination, could bolster the immune systems of veteran patients who have built resistance to earlier generation of drugs.

"This is a really exciting time for patients," Isaacs said.

But Isentress won't be cheap. Immediately after receiving FDA approval to market the drug, Merck disclosed that it plans to sell Isentress for $27 a day, or $9,850 per year - making it one of the costlier pills on the market.

A new drug by Pfizer Inc., Selzentry, sells for at least $10,600 a year. The Pfizer pill, which received FDA approval in August, also represents a new class of AIDS drug. This one blocks a structure on the surface of blood cells called CCR5, which the AIDS virus uses to wedge its way into cells.

Martin Delaney, founder of San Francisco's Project Inform - a leading AIDS drug advocacy organization - and an activist in a group called the Fair Pricing Coalition, said Merck is not charging as much as he had feared.

"It falls in the middle of the high end for AIDS drugs. For us, that is a victory," he said.

Although tests have shown that Isentress does not cause common HIV drug side effects such as driving up levels of fat cells in the blood, early animal studies showed that the drug might cause cancer in rats. Human trials have shown a 20 percent higher risk of cancer in patients, compared with those who took a placebo.

But Merck scientists said the elevated risk appears to be the result of chance - cancer rates in the placebo group were lower than is typical among AIDS patients, and as testing has continued, the small number of cancers in both groups has been balancing out.

Gladstone AIDS researcher Greene also said he believes the new integrase inhibitor will prove safe because there are no known biological reasons why the drug might cause cancer. Greene said he has no economic ties to Merck.

Pharmaceutical researchers are fond of targeting enzymes because these catalysts play powerful roles in biological processes. Block an enzyme, and an entire chain of molecular events that promote disease might be broken. Enzymes are also vulnerable to molecules that can be made small enough to be taken in pill form and be carried by the blood throughout the body.

The first generations of AIDS drugs targeted reverse transcriptase, an enzyme that HIV uses to convert its genes into the DNA code used by human cells. The second generation of AIDS drugs attacked HIV protease, an enzyme that helps newly formed viruses escape the cells where they have been replicating.

Friday's FDA approval is the culmination of 14 years of research by Merck to find an integrase inhibitor. It turned out to be a daunting challenge that frustrated other drug companies for years. Another integrase inhibitor by Gilead Sciences Inc. of Foster City is undergoing large-scale clinical trials.

Robert Rode, a Merck marketing vice president, said the new pills should be available in pharmacies in as few as two weeks. The company has been providing Isentress free to 6,000 patients worldwide, including 3,400 in the United States, while the company awaited FDA marketing approval.

He said a program is in place at Merck to "make this product available globally." The company has provided steep discounts for its AIDS drugs overseas, but the high cost of branded antiviral drugs remains a hurdle for international control of the epidemic.


E-mail Sabin Russell at srussell@sfchronicle.com

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More info @ POZ.com:

https://www.poz.com/drug/isentress

[aztecan]

I've seen a couple of things about this. Sounds exciting doesn't it!

HUGS,

Mark