Sabril/vigabatrin

Saw the link to this Forbes article in the IS forum. Interesting read about how the only infantile spasm approved drug made it's way to FDA approval.


A Long And Deadly Wait
Matthew Herper, 09.30.09, 06:00 AM EDT
Sabril could help babies with brain-destroying seizures. So why did it take so long to approve?



Timothy Zirkel will never forget the seizures that assaulted his 4-month-old son, Jake. "You could see the pain in his body as it happened," says Zirkel. "I just remember always wanting to trade places with him."

Every seizure was damaging Jake's brain. Infantile spasms, a rare form of epilepsy, strike 2,500 babies in the U.S. every year. Unless the seizures are stopped early, permanent neurological problems result. These children may never walk or talk. Some have IQs of less than 50.

After a first treatment failed, Jake was helped by an experimental medicine called Sabril that carried the risk of destroying his peripheral vision.

It was "a no brainer" to take the chance, says Zirkel. "Within the first day of taking it, his seizures stopped and they have never come back." That was in 2005.

The drug had languished since 1998 when its original maker abandoned it because of the vision side effects. A tiny biotech, Ovation Pharmaceuticals, picked it up in 2003, and fought for six years to get it approved. Its path to patients was the longest of any medicine on record--14 years.

Sabril warrants close attention because it's a clear near-miss for the drug approval system, a case where a medicine with a clear benefit for desperate patients foundered. It's pretty clear that new conflict of interest rules and policies about drug safety contributed to the delay. A small potential market--sales are expected to peak at $300 million--also played a role.

Unlike the controversy over, say, the Dendreon cancer treatment Provenge, there have been few protests and little noise made about the delay. Even now, Ovation's parent company, Lundbeck, will probably make more from selling Sabril to adult epileptics than to babies. Figuring out how to help small groups of people who desperately need a drug without exposing the population at large to necessary risks may be the biggest challenge facing the FDA.

In 1994, Marion Merrill Dow, now part of Sanofi-Aventis ( SNY - news - people ), filed a new drug application for the drug as a treatment for all kinds of epilepsy. In November 1997, the FDA asked for more information about the drug's efficacy. A month later, the first reports emerged that patients in Europe were losing their peripheral vision. Forty percent of the patients who take Sabril have this side effect. In October 1998, the FDA rejected the drug.

That would have been that had it not been for Donald Shields, director of the pediatric epilepsy program at UCLA. In 1996, Shields and his colleague Roy Elterman had started a study of Sabril in infantile spasms. Even after the company backed out, they kept enrolling babies in the study until their supply of the medicine expired, eventually enrolling 200.

They published their results in the journal Neurology in 2001. Patients who were given a high dose of Sabril were three times more likely to have their seizures stop than those who received a low dose. (Because the patients needed treatment, all got at least a low dose of the drug.)

"It's the kind of drug we have to have," says Shields. "It's got its problems, but for the kind of patients we're talking about, it is a godsend."

At a meeting of the Child Neurology Society in Vancouver, Shields saw a booth for a new start-up, Ovation Pharmaceuticals, which was seeking new products. He sold them on Sabril. The FDA had never closed the file on the drug, and in December 2007, Shields' data formed the basis of a new drug application for infantile spasms.

The FDA gave the drug "priority review," which means a decision was due in six months. But from the outset, the agency said it would need extra time to convene a panel of experts to weigh Sabril's merits. Experts in infantile spasms were few and far between.

Then new regulations slowed things down even more. The FDA was facing enormous pressure following controversies like the withdrawal of Merck's ( MRK - news - people ) painkiller Vioxx, linked to heart attacks, and alleged overuse of anti-psychotic drugs like Zyprexa from Eli Lilly ( LLY - news - people ) and Seroquel from AstraZeneca ( AZN - news - people ). New conflict of interest rules led it to cancel a July 2008 panel for Sabril because one key expert no longer qualified.

The FDA finally convened its panel in January 2009, and the panelists voted unanimously that Sabril should be approved both for babies with infantile spasms and for adults who had run out of options. In February, Lundbeck, a Danish drug maker, bought Ovation for $900 million. The press release announcing the deal trumpeted that Sabril was in the final stages of FDA review.

But Sabril needed a Risk Evaluation and Mitigation System (REMS), FDA jargon for a plan that ensures drugs are only used when benefits outweigh risks. One division was uncomfortable with the measurements on the dosing syringe in which the drug was given, and even after the review seemed close to done, a team of lawyers had to go over it. Sabril was finally approved in August.

Shields "whooped" when the approval came through. On the length of the delay, he says only, "The FDA and I have very different jobs."

"I would rather have a blind child who is not suffering neurological damage than the reverse," says Tim Zirkel. He asks himself how many kids have suffered as the drug made its way to the market. Kids whose seizures are stopped early enough are normal developmentally. Jake Zirkel is not quite that lucky. He walks and says a few words, but doesn't talk as much as a normal 4-year-old.

"My son is the most amazing child," Zirkel says. "He is my biggest hero. He has gone through more in the past four years than I ever will."