Elan Corp. plc decided to sell the European rights to its pain product Prialt, but is keeping U.S. rights, where the drug already is being sold.

Tokyo-based Eisai Co. Ltd. is buying the rights in a deal worth up to $100 million in cash.

Broken down, that means Dublin, Ireland-based Elan will receive $50 million on the closing of the transaction; an additional $10 million upon launches of Prialt in key European markets, or two years after closing, whichever comes first; and up to $40 million on the achievement of revenue-related milestones in Europe. Since it is a straight sale, the deal does not include royalties.

Elan received European regulatory approval for Prialt earlier this month and had always planned on selling the rights there, said Davia Temin, a spokeswoman for the company.

"The motivation was to help get this medicine to patients in Europe as quickly as possible," she told BioWorld Today.

Eisai recently had expressed an interest in expanding its range of products and already has the infrastructure in place to sell those indicated for pain.

"Eisai really is a perfect partner," Temin said. "They have a lot of experience with pain medications in Europe, and Elan has partnered with them previously and has worked with them very, very well."

In April 2004, Elan sold exclusive North American and European manufacturing, development and marketing rights for Zonegran (zonisamide) to Eisai for $130 million. The drug was developed and marketed by Elan for the adjunctive treatment of partial seizures in adult epilepsy.

The Prialt sale should close this quarter and is subject to regulatory approvals and other customary closing conditions. Elan expects to record a gain at closing of more than $40 million.

The company is keeping all product rights to Prialt in the U.S., which received FDA approval in December 2004 for the management of severe chronic pain in patients who need intrathecal (IT) therapy, and who are intolerant or refractory to treatments such as IT morphine, systemic analgesics and adjunctive therapies. (See BioWorld Today, Dec. 30, 2004.)

Its approval was somewhat overshadowed by the clearance given a month earlier to Tysabri, a drug developed for the much larger indication of multiple sclerosis by Elan and Cambridge, Mass.-based Biogen Idec Inc. But serious side effects led to the withdrawal of that product a few months later, and today, Prialt is the only one making money for Elan. Launched in the first quarter of 2005, it had full-year revenue of $6.3 million. (See BioWorld Today, Nov. 29, 2004, and March 1, 2005.)

At the time of the U.S. approval, however, Elan said Prialt could grow to $250 million per year in peak sales, while some analysts expected Tysabri to reach $2 billion in peak sales.

Prialt (ziconotide) has orphan drug status in the European Union, where it will treat severe, chronic pain in patients who require intrathecal analgesia. Severe, chronic pain lasts longer than six months and can be caused by failed back surgery, injury, accidents, cancer, AIDS and other nervous system disorders. The U.S. market includes about 120,000 patients.

Elan gained ownership of Prialt when it acquired Neurex Inc., of Menlo Park, Calif., in 1998 in a $741 million stock swap. The drug is in a class of non-opioid analgesics known as N-type calcium channel blockers.

"It is the synthetic equivalent of a naturally occurring conopeptide that’s found in this marine snail" known as Conus magus, Temin said. "It works by targeting and blocking N-type calcium channels on nerves that transmit pain signals. That’s the mechanism of action."

There has been a lot of interest in the product, she added, because it comes from nature and represents a new way of treating chronic pain.

"Prialt is one of the first non-opioid pain relievers to come out in about 20 years," Temin said.

It is administered through implanted or external microinfusion pumps that release the drug into the fluid surrounding the spinal cord. The European approval was based on three independent pivotal studies that demonstrated significant improvements on the Visual Analog Scale of Pain Intensity.

Elan’s stock (NYSE:ELN) rose 5 cents Thursday to close at $14.45.

No Comments