Past the primary function
ICOS of Bothell is researching more medical uses for its erectile dysfunction drug Cialis
By Eric Fetters
Herald Writer
BOTHELL - The world knows Cialis as a drug for men, an increasingly popular rival to Viagra that helps with erectile dysfunction.
But ICOS Corp. sees new medical tricks for its flagship drug. Cialis' active ingredient, it turns out, could help men and women lower their blood pressure, keep a common prostate condition under control and even tackle a potentially fatal lung disorder.
The multiple uses for the drug also could brighten the future at ICOS, which has faced setbacks in early attempts to develop a follow-up drug to Cialis.
"We always are trying to figure out where else this drug may be of benefit," said David Goodkin, senior vice president of development and chief medical officer at ICOS.
Cialis' active ingredient, tadalafil, originally was developed as an angina drug years ago before researchers honed in on its effectiveness against impotence. It works by relaxing smooth muscles and tissues in blood vessels and arteries, allowing for more effective blood flow.
ICOS announced earlier this month that it will try to harness the drug's mechanism as a treatment for hypertension, or chronic high blood pressure.
"There are many high blood pressure medicines in the U.S.," Goodkin acknowledged. "And yet, of the 50 million people with high blood pressure in the U.S., it's estimated that only 17 million are being treated. So there's always a need for more."
Lilly ICOS also is enrolling patients in a phase 3 study on using tadalafil against benign prostatic hyperplasia, a common enlargement of the prostate. More than half of men over age 50 have symptoms caused by benign prostatic hyperplasia, according to estimates cited by ICOS.
Data from the phase 2 study released by ICOS showed results that were "clearly clinically meaningful and comparable to drugs" already on the market, Goodkin said. Again, the main difference between tadalafil, if it is approved as a prostate treatment, and its rivals will be the side effects. While other drugs can hinder sex, Cialis would have the opposite effect.
The third target that Lilly ICOS has identified for tadalafil is pulmonary arterial hypertension, a rare lung condition characterized by elevated blood pressure or arterial blockage in the arteries of the lung.
Affecting approximately 100,000 people in the U.S., 64 percent of whom are women, the sometimes fatal condition causes shortness of breath, fatigue and heart failure. Once diagnosed, usually between the age of 20 and 30, the median length of survival is less than three years, Goodkin said.
Existing treatments include drugs that have to be given intravenously and a pill with potential side effects on the liver. Sildenafil, the active ingredient in Viagra, also recently was approved as a treatment.
While none of the additional uses for tadalafil has yet been approved as safe and effective, the possibility is enticing to the company's investors.
"The BPH market alone, in theory, could double the size of the company," said Paul Latta, a biotech analyst who tracks ICOS for Seattle's McAdams Wright Ragen. "In fact, that may be conservative. And hypertension is an enormous market, too."
Goodkin and others at ICOS point out that a large number of patients who suffer from erectile dysfunction also have one of the other conditions that Cialis' ingredient could treat. For example, men with prostatic hyperplasia often also suffer impotence. Forty-one percent of men with erectile dysfunction have hypertension, Goodkin said.
Biotechnology companies usually can't survive in the long run by relying on sales of one drug, even if it's a near blockbuster like Cialis. While only a small percentage of drug candidates makes it through the required clinical trials, having a backlog of potential drugs under development is important.
After the failure of at least a half-dozen potential drugs in clinical tests between 2002 and early 2005, ICOS' pipeline worried some investors earlier this year.
The company now lists nine other drug candidates besides tadalafil, but all of those are in the preclinical research stage, meaning their safety and effectiveness haven't been tested.
Latta said the multiple uses being explored for tadalafil, however, have eased investors' expectations for other drugs under development. But, he added, "ultimately, you always need to be working on the pipeline."
David Miller, president of Biotech Stock Research in Seattle, said basing the majority of a firm's pipeline on one active ingredient carries extra risks.
"There are very few wonder compounds," he said. "Those drugs are pretty rare, so you have to understand that and be careful."
Goodkin said, however, that tadalafil's proven safety and effectiveness in Cialis means that fewer early-stage tests are required when developing the drug for other uses. That saves years of research and millions in dollars.
"Needless to say, we'd love to have many different molecules in the pipeline and in clinical trials, but this isn't a bad thing for the company," he said.
Nov. 21 marks the second anniversary of Cialis' approval by the U.S. Food and Drug Administration. Since the erectile dysfunction drug went on sale in early 2003, it has surpassed $1 billion in total worldwide sales. Estimated sales of Cialis this year alone are expected to exceed $730 million. In the U.S., about 25 percent of prescriptions for erectile dysfunction drugs are written for Cialis, compared with 63 percent for Viagra and 12 percent for Levitra. Cialis' share of the market has grown every month since the U.S. launch.
There's especially a need for high blood pressure drugs that don't have the major side effects common with existing remedies. The joint venture formed by Eli Lilly and ICOS to develop and market Cialis has begun a phase 2 human study on using tadalafil against this condition.
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