Northstar Neuroscience (Seattle) might have struck out with its EVEREST pivotal trial for studying cortical stimulation for stroke patients, but it intends to move forward with its PROSPECT feasibility study for cortical stimulation for depression, the company said late last week.

"Now our biggest goal is to get FDA approval and move forward with the enrollment of a larger depression study," John Bowers, president/CEO of Northstar Neuroscience, told Medical Device Daily. "We don't have any other projects on the backburner."

The company released results of the PROSPECT feasibility study during the American Society for Stereotactic and Functional Neurosurgery (ASSFN; Manhassett, New York) meeting in Vancouver, British Columbia, last week.

Cortical stimulation therapy is a method for the precise delivery of low levels of electricity to the outer layer of the brain via an implanted stimulator system. To do this, the company uses the Renova, a device in which electronic leads are implanted along the outer layer of the brain, running through a small generator that is monitored by a physician.

Results of cortical stimulation for the treatment of major depressive disorder were presented on behalf of the PROSPECT investigators by Brian Kopell, MD, of the Medical College of Wisconsin (Milwaukee) and Northstar's VP of medical affairs.

PROSPECT is a multi-center, randomized, single-blind study being conducted at Massachusetts General Hospital (Boston) the University of Pittsburgh and the Medical College of Wisconsin.

In the PROSPECT trial for depression, the patients received 16 weeks of active stimulation. Hamilton Depression Rating Scale scores improved by an average of 27% from baseline and the Montgomery-Asberg Depression Rating Scale scores improved by 31% from baseline.

The Global Assessment of Functioning (a scale used to rate the social, occupational and psychological functioning) scores improved by 50% from baseline, indicating an improvement in patient's quality of life and ability to function. Each of these rating scales indicated a continuing trend of improvement at 16 weeks.

According to PROSPECT data, out of the 12 patients who underwent cortical stimulation for depression in the trial, four had improvement greater than 50% and one had improvement right at 49%.

"Right now we're still relatively early in the investigative stage," Kopell said. "We hope to be able to enroll patients in a much larger study at the end of this year. As far as when this product will launch, we're still a number of years out before this product can be marketed."

In January the company received a tremendous blow, when it failed to meet the primary endpoints for its EVEREST pivotal trial which sent the company's stock plunging 83% (Medical Device Daily, Jan. 23, 2008).

"Unfortunately we didn't meet our primary endpoint," Bowers said.

The results for EVEREST included:

At the four-week follow-up, 30.8% of the patients receiving cortical stimulation achieved the threshold of clinically meaningful improvement for the composite primary efficacy endpoint defined in the study protocol, compared to 29.1% of the patients in the control group.

The primary efficacy endpoint required a 20% absolute difference between these two groups.

Presenting on behalf of the EVEREST study investigators, Robert Levy, MD, of Northwestern University (Evanston, Illinois) reported data on cortical stimulation for the recovery of hand/arm function following stroke through 12 and 24 weeks following therapy.

The data once again confirms the safety profile of cortical stimulation and suggests that rehabilitation for chronic stroke patients can make a difference. As reported earlier, the EVEREST success criteria at the four-week primary endpoint was not achieved, and analysis of the data set through the 24 week follow up period indicates the overall treatment effect also did not reach statistical significance. However, specifically at the 24 week time-point, there was a statistically significant improvement in the Arm Motor Ability Test (AMAT), one of the study's key outcome measures for activities of daily living, for the treatment group compared to control.

Additionally, Levy presented follow-up data on the previously reported "evoked movement" subset of cortical stimulation patients who achieved statistically significant improvements compared to control patients at the four week follow up. Through 24 weeks, these patients retained statistically significant benefits compared to the control group.

Neurostimulation is a rapidly emerging field. To date the number of companies trying to garner a foothold in the space are growing.

Some of the other key players in the neurostimulation space include Advanced Neuromodulation Systems (Plano, Texas), Medtronic (Minneapolis), Boston Scientific (Natick, Massachusetts) and Cyberonics (Houston).

Northstar was founded in 1999 and has 58 employees. The company has a market capitalization of $44 million. As of yesterday, Northstar opened at $1.70 a share and closed at $1.72 a share.