Aastrom Maps Out Pivotal Trial Strategy With Adult Stem Cell Therapy

Xconomy Detroit/Ann Arbor — 

Biotech is one of the most regulated businesses on the planet, so it’s clear that if Aastrom Biosciences is going to get anywhere, it had better have a good strategy for working with U.S. drug regulators. This week, the Ann Arbor, MI-based company took a couple of important steps in the direction that investors like to see.

On Monday, Aastrom (NASDAQ: ASTM) said its experimental adult stem cell therapy was granted “Fast Track” designation by the FDA, which means it is eligible for a faster-than-usual six-month review that regulators sometimes grant for new life-saving therapies. A couple days later, Aastrom filed its all-important pivotal stage clinical trial proposal for review by the FDA. If the agency agrees this is a well-designed experiment that can prove the value of the Aastrom approach, then the company could start recruiting patients before the end of March.

This clinical trial is being designed to enroll between 500 and 600 patients with critical limb ischemia (CLI). This is a severe form of cardiovascular disease in the legs, known as peripheral artery disease, in which blood vessels get so clogged up that doctors choose to amputate. Aastrom’s approach involves withdrawing a patient’s bone marrow cells, incubating them in a proprietary process at its Ann Arbor facility, and spurring growth of adult stem cells and progenitor cells that promote healing. Those revved up cells get re-infused into the patient, and they are supposed to foster growth of new blood vessels to improve circulation.

There could still be some back-and-forth negotiating left between the company and regulators about the design of this trial, but a few important elements are already known, says Aastrom CEO Tim Mayleben. Like a recent (failed) trial Sanofi-Aventis ran for critical limb ischemia, the Aastrom study will be designed to see if its method can reduce the rate of amputations, and death, after 12 months of follow-up, Mayleben says. It will enroll patients in North America. It will probably take 18 months to recruit them all, and another year of follow-up, he says. An independent panel of experts will review the blinded study data part-way through, probably in the second half of 2012, and recommend whether researchers should keep going, or whether to pull the plug.

Tim Mayleben

Tim Mayleben

The study is a big, bold wager for a company like Aastrom, with a market valuation of a little more than $40 million. It will cost about $30,000 to $35,000 per patient to conduct the study, and the total budget will run between $15 million and $20 million, Mayleben says. So there’s obviously pressure to make sure the company is on the same page with the FDA, and to get the trial done right the first time.

“We don’t expect a lot of disagreements with the agency,” Mayleben says. “We’ve had a good collegial discussion with them thus far. We understand where they are coming from, and they understand where we are coming from. Our goals are to bring forward a new treatment for critical limb ischemia.”

One of the important points for regulators, and the company, is that this trial shouldn’t be plagued by the kinds of subjective biases that often trip up other companies. With cancer drugs, for example, researchers who treat patients often look at a CT image to see if a tumor is really shrinking, and they often have different opinions than radiologists who look at the same picture in a central office. Tumor shrinkage itself is really just a “surrogate” measurement that’s supposed to provide a quick read on whether a drug is actually going to help people live longer, the gold standard for success in cancer drugs.

But with critical limb ischemia, patients have essentially run out of options other than amputation. About one-fourth of patients die within the first year of diagnosis, and less than one-fourth of patients survive as long as four years. So a trial that straightforwardly measures survival and amputation rates is practical for a company of Aastrom’s size to run, and will provide hard objective data that will say whether it’s working.

“If your therapy works, you know it, and if it doesn’t work, you know that too,” Mayleben says.

Besides the interactions with the FDA, which will probably take a couple months to nail down, the next big item on Aastrom’s to-do list is an appearance at the VEITH symposium, a meeting of vascular surgeons in New York in November. We’ll keep an eye out for those findings to see if it says anything really new about the Aastrom approach, and offers much confidence on whether it might work in the upcoming Phase III trial.

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