June 17, 2008 -- Experts told the FDA Tuesday that it should approve an experimental psoriasis drug despite evidence the drug may cause cancer after long-term use.
The medication, called ustekinumab, has been shown to reduce the itchy and scaly symptoms of the moderate and severe forms of the skin disease psoriasis. But FDA scientists also expressed concern over animal studies showing the drug can promote lymphoma.
In a 9-1 vote, with one abstention, an FDA advisory panel said the benefits of the drug outweigh the potential risks of cancer. That was after experts said the manufacturer had not studied the drug sufficiently to know its long-term cancer risks. The FDA doesn't have to follow its panels' recommendations, but it usually does.
Efficacy Sways Panel
Panelists said they were ultimately convinced by ustekinumab's demonstrated ability to relieve psoriasis, a disease with devastating psychological consequences for many of the estimated 8 million Americans who suffer from it -- a factor most said outweighed a theoretical risk of cancer.
"The remarkable efficacy I think is a very convincing factor," said Arthur Levin, MPH, director of the Center for Medical Consumers and a member of the expert panel.
"If you concentrate on risk-benefit compared to almost everything else we have available, the drug looks pretty good," said Michael Bigby, MD, the panel's chairman.
Ustekinumab works by targeting inflammatory chemicals called interleukins which are elevated in patients with psoriasis. That helps cut down on the inflammation at the root of many psoriasis symptoms. A pair of trials by manufacturer Centacor, a division of Johnson & Johnson, showed the drug can reduce redness, itching, and skin flaking, and the panel voted unanimously that the drug is effective.
Most patients also have to take ustekinumab injections only every three months, a far less frequent schedule than with other drugs, the company said.
But inhibiting the chemicals could also play a role in promoting cancerous tumors. Studies in mice that showed use of the drug can promote lymphoma cancers were a concern to FDA scientists.
"Long-term use of ustekinumab may lead to increased risk of tumor development in psoriasis patients," the FDA told its advisors in briefing documents this week.
Experts said they were concerned over those risks. The company's studies of ustekinumab lasted less than a year, causing concerns that longer treatment could carry unknown risks.
"I wouldn't know how to conduct the long-term therapy with this drug," said Susan Heckbert, MD, a professor of epidemiology at the University of Washington in Seattle and a member of the expert panel. "This disease goes on for years and years."
Other injectable therapies for psoriasis called biologics also target chemical triggers of the immune system. Drugs such as Enbrel and Humira work in similar ways to reduce the psoriasis severity index -- a clinical marker of inflammation. But ustekinumab targets different biological chemicals than the other available drugs.
The panel called on the FDA to require Centacor to closely track patients taking the drug for any signs of cancer. Many also said the agency should require registries and other restrictions that would limit ustekinumab's use.
Robert Stern, MD, a panel member and professor of dermatology from Harvard University, said Centacor should be held to "enforceable milestones" of studying patients and "some real penalties" if those benchmarks are not met. A new law allows the FDA to fine companies that don't meet commitments to study their new drugs once they're on the market.
"They haven't told us how safe it is to use this drug by any stretch of my imagination," Stern said.