First efficacy trial of Athersys stem cell therapy yields disappointing interim results. So what now?

Edited to include comments from CEO. Halfway through its first large-scale efficacy trial, Athersys’s experimental stem cell therapy did not provide significant benefit to patients with moderate-to-severe ulcerative colitis. But the company isn’t too worried about what that might mean just yet. Cleveland-based Athersys (NASDAQ: ATHX) released the interim results today for the Phase 2 […]

Edited to include comments from CEO.

Halfway through its first large-scale efficacy trial, Athersys’s experimental stem cell therapy did not provide significant benefit to patients with moderate-to-severe ulcerative colitis.

But the company isn’t too worried about what that might mean just yet.

Cleveland-based Athersys (NASDAQ: ATHX) released the interim results today for the Phase 2 study it’s conducting with Pfizer. The randomized, double-blind, placebo-controlled study has enrolled 88 ulcerative colitis patients in the U.S., Canada and Europe who have had the disease for an average of about 10 years and did not respond to prior treatment.

Forty-eight of them received a single IV dose of MultiStem, the company’s off-the-shelf stem cell therapy that’s shown preclinical promise in reducing inflammation, protecting damaged tissue and forming new blood vessels.

Eight weeks after treatment, the MultiStem group overall didn’t experience a significant reduction in severity of disease and rectal bleeding compared to the placebo group, Athersys said. (Primary endpoints were measured by changes in Baron scores and Mayo rectal bleeding subscores.)

Another round of data will come this summer describing 16-week outcomes, but Athersys Chairman and CEO Gil Van Bokkelen said he doesn’t expect that data to tell a different story.

“This data told us that one dose isn’t enough to generate meaningful response in this particular group of patients,” he explained. That answers the question that Athersys and Pfizer set out to answer with this trial, but doesn’t mean that the therapy couldn’t be effective in a different dosage, or in a different subset of patients. “We’re focused on completing the study, and then we’re all going to take a look at it and decide where to go from there.”

Athersys is concurrently developing and testing MultiStem, an off-the-shelf stem cell therapy, in several other indications including graft-versus-host disease and heart attack. It’s recruiting for a Phase 2 trial in ischemic stroke that’s expected to produce initial results later this year.

Studying the therapy in these other indications will be much different from the ulcerative colitis study, Van Bokkelen said. Stroke, for example, is an acute indication where the therapy will be administered with days of onset, rather than within years or even decades of onset as in the ulcerative colitis study. “It’s a bit like getting a ship from point A to point B,” he said. “If you can make a much smaller turn early in the process, it will have a bigger impact later on.”

The treatment did show a positive safety and tolerability profile consistent with previous studies, the company said.

Its stock was down more than 50 percent this morning.

[Image credit: FreeDigitalPhotos user moggara12]