BioWorld International Correspondent

Elan Corp. plc aims to launch its non-opioid peptide-based analgesic Prialt "no later" than the first quarter of 2005, following news that the compound met its primary endpoint in a trial of 220 patients with severe chronic pain who had not obtained relief with other therapies.

The Dublin, Ireland-based pharmaceutical company hasn't released the results of the study, but plans to do so at an appropriate scientific meeting later this year. It said Wednesday that Prialt (ziconotide) achieved a statistically significant improvement at week three in the Visual Analogue Scale of Pain Intensity (VASPI) score.

Elan gained ownership of Prialt, a synthetic derivative of a peptide isolated from the venom of a Conus species of marine snail, when it acquired Neurex Inc. in 1998 in a stock swap valued at $741 million. The product, the first in its class, acts by blocking a neuron-specific N-type calcium channel. It is administered intrathecally, that is, into the cerebrospinal fluid surrounding the spinal cord, via a subcutaneously implanted pump supplied by Medtronic Inc., of Minneapolis.

The compound has a development history stretching back to the mid-1990s and was the subject of an FDA approvable letter in 2001 that asked for additional data. Since then, Elan has worked with the agency on the design of a study to evaluate its efficacy at a lower dosage and a slower titration rate than those used in two previous pivotal studies.

"The data from this study, then, represent the final element of this process and will be filed as an amendment to our new drug application with the FDA in the second quarter of this year," Lars Ekman, executive vice president and president of research and development at Elan, said in a conference call.

On the same call, CEO Kelly Martin said the product would be targeted at around 50 pain treatment centers in the U.S., saying, "We're quite familiar with them, and they're quite familiar with us." Some 39 of them were involved in the recent clinical study. The product will be aimed initially at three groups: cancer patients, AIDS patients with chronic pain and patients with neuropathic pain.

Martin said peak annual sales for Prialt could lie between $150 million and $250 million, based on a total potential market of 300,000 patients with chronic pain who are considered suitable candidates for intrathecal treatment.

"Three-thousand dollars to $4,000 per patient per month in this market space looks like the revenue opportunity," he said.

Only 30,000 to 50,000 patients have so far been fitted with the Medtronic device, although availability of Prialt could push that figure higher, Martin said.

"It's very hard to gauge how they're going to penetrate the market," said David Marshall, analyst at NCB Stockbrokers in Dublin. The company's most immediate target, he said, is likely to be that fraction of patients using intrathecal pumps who have become refractory to morphine or who suffer from respiratory side effects through its use.

"They may be able to capture that portion of the market quite quickly and have a slow ramp from there," he said.