Positive results from phase I clinical trial of MultiStem in patients with AMI announced

Angiotech Pharmaceuticals, Inc. (NASDAQ: ANPI, TSX: ANP) ("Angiotech") and partner Athersys, Inc. (NASDAQ: ATHX) announced positive results from its phase I clinical trial of MultiStem(R), its allogeneic cell therapy product, administered to individuals following acute myocardial infarction (AMI), more commonly referred to as a heart attack. The study results, which represent at least four months of post-treatment patient data, demonstrate that MultiStem was well tolerated at all dose levels and also suggest improvement in heart function in treated patients.

The phase I clinical trial is an open label, multi-center dose escalation trial evaluating the safety and maximum tolerated dose of a single administration of allogeneic MultiStem cells following an AMI. Enrolled patients received MultiStem delivered via a catheter into the damaged region of the heart 2-5 days following percutaneous coronary intervention (PCI), a standard treatment for heart attack. The study includes patients in three treatment cohorts or dose groups (20 million, 50 million and 100 million cells per patient) and a registry group where patients received only standard of care. Nineteen treated and six registry subjects participated in the study. The trial is being conducted at cardiovascular treatment centers in the United States, including the Cleveland Clinic, Columbia University Medical Center and Henry Ford Health System.

Highlights of the Study:

- Administration of MultiStem was found to be well tolerated at all dose levels - No clinically significant changes in vital signs, allergic reactions, or infusion-related toxicities were associated with MultiStem administration - Each dose group showed improvement in mean left ventricular ejection fraction (LVEF), a measure of heart function, compared to baseline and relative to the registry group - Patients in the 50 million dose group had a statistically significant absolute improvement in mean 4-month LVEF relative to baseline (9.8 percentage points, representing a 23.4% improvement over baseline, p less than 0.02) - Among patients with more severe heart attacks - as measured by baseline LVEFs less than or equal to 45% - the 50 and 100 million dose groups each demonstrated better than a 25% improvement in mean LVEF at 4 months post treatment over baseline

"Myocardial infarction remains one of the leading causes of death and disability in the United States," said William Hunter, M.D., President and CEO of Angiotech. "We believe these positive Phase 1 results validate the value of our partnership with Athersys, and we are looking forward to working with Athersys to formulate the next clinical development steps for this important product candidate."

Dr. Marc Penn, M.D., Ph.D., co-principal investigator of this study and Director of Cardiovascular Cell Therapy at the Cleveland Clinic, and Director of the Skirball Laboratory for Cardiovascular Cellular Therapeutics, plans to present additional data and results and further discuss the study on September 22, 2010 in Washington, D.C. at the Symposium "Strategies for Cardiovascular Repair: Stem Cell Therapy and Beyond," at the Transvascular Cardiovascular Therapeutics Conference.

"These phase I results suggest that MultiStem is well tolerated when administered to the damaged region of the heart following a heart attack," said Dr. Penn. "MultiStem's safety profile, together with trends suggesting meaningful improvement in functional measures, illustrates the potential of this therapy in this area and supports further clinical study of MultiStem for the treatment of heart disease."

During the first 24 hours following MultiStem administration, patients were assessed for infusion-related toxicity and other acute adverse events. Subsequently, patients were evaluated for cardiac adverse events. The primary endpoints for the study were the assessment of acute adverse events during the first 24 hours following administration, post-acute adverse events up to 30 days, and catheter-related events.

The administration of MultiStem was found to be well tolerated at all dose levels evaluated. There were no dose limiting toxicities associated with the administration of MultiStem. Immediately following dosing, there were no clinically significant changes to vital signs or evidence of allergic reaction associated with MultiStem administration. Over the 30-day post-acute observation period, no infusional toxicities or clinically significant cardiac adverse events deemed to be definitely related to MultiStem occurred.

MultiStem had a favorable safety profile over the four-month period following treatment. There was no dose dependent effect of MultiStem on adverse events (AEs) and generally AEs were mild to moderate in nature. Overall, there were several observed AEs characterized as potentially related to MultiStem or catheter delivery. These were generally mild to moderate in nature and were not dose dependent.

Heart Function

While the primary objective of this phase I study is to evaluate the safety of MultiStem administered to AMI patients, echocardiogram data are being collected and evaluated for evidence of efficacy signals to facilitate planning for subsequent clinical studies, noting importantly that the study was not powered for efficacy endpoints. Specifically, following a heart attack, patients were screened by left ventriculogram and/or echocardiogram, analyzed at the clinical site, to determine if their LVEFs met inclusion criteria (30 to 45). Prior to MultiStem administration (and between 2-5 days following PCI for registry patients), an additional echocardiogram was performed, which served as the baseline for subsequent analysis. Additional echocardiogram data were collected at prescribed time points according to the protocol. Echocardiogram data collected for each patient were blinded, and evaluated at a central facility.

The preliminary echocardiogram data demonstrated that each group had improvement in mean LVEF at four months compared to mean baseline LVEF. Patients receiving 20, 50, or 100 million MultiStem cells demonstrated absolute improvements in mean LVEF at 4 months of 5.2, 9.8 and 1.5 percentage points, respectively, compared to an absolute improvement of 1.1 percentage points in the registry group. Although the study was not powered for efficacy endpoints, patients in the medium dose group exhibited a statistically significant improvement in LVEF over mean baseline for that group, 9.8 percentage points (p less than 0.02), representing a 23.4% improvement over baseline. The improvement in mean LVEF for each group compared to the registry group, though meaningful, was not statistically significant.

Notably, several patients in the high dose group exhibited substantially higher baseline LVEFs than their initial screening LVEFs, which created a higher baseline mean for that patient group. Including only patients whose baseline LVEFs are less than or equal to 45, the absolute improvements in mean LVEF were 3.9, 13.5 and 10.9 percentage points for the 20, 50, or 100 million dose groups, respectively, compared to an absolute improvement of 0.9 percentage points in the registry group. Among these patients (i.e., LVEFs less than or equal to 45), those in both the medium and high dose groups exhibited a substantial increases in LVEF, representing more than 25% improvements relative to baseline LVEF for those patient groups. Additional analysis of the echocardiogram data is ongoing, and we will evaluate possible effects on other measures of heart function.

"These preliminary phase I MultiStem results are consistent with the results obtained in preclinical studies and compare favorably to the results from other cell therapy treatments for AMI. This suggests that MultiStem could have a meaningful impact on improving heart function following heart attack," stated Dr. Warren Sherman, co-principal investigator and Director of Stem Cell Research and Regenerative Medicine, Center for Interventional Vascular Therapy at Columbia University Medical Center in New York.

Further Evaluation and Development

Athersys and Angiotech will continue to evaluate the phase I results and intend to begin planning for a subsequent clinical study, which they currently anticipate will be initiated in 2011. Further guidance about subsequent clinical development, such as trial design and timing, will be provided after evaluation and planning are completed and discussion with the FDA has occurred.