Athersys Reports TREASURE Phase 2/3 Trial of MultiStem (invimestrocel) for Ischemic Stroke Did Not Meet Primary Endpoint

On May 20, Athersys announced that the Phase II/III study, code-named TREASURE, conducted by its partner HEALIOS K.K. on ischemic stroke patients in Japan using the stem cell therapy product MultiStem (invimestrocel), did not meet the primary endpoint.

This randomized, double-blind, placebo-controlled study enrolled a total of 206 patients with moderate to moderately severe ischemic stroke (baseline NIHSS 8-20), who were administered a single intravenous dose of MultiStem or placebo treatment within 18-36 hours after the occurrence of stroke.

The main results of the study are as follows:

The pre-specified evaluation metric "Independence" showed improvement and achieved a "Good Outcome," such as: modified Rankin Scale (mRS) score ≤2, Barthel Index ≥95, and overall recovery status.

Did not reach the primary endpoint of achieving an "excellent outcome" by Day 90;

Overall, after a year, the measurement results of basically all evaluation functions have continued to improve, supporting the long-term impact and continuous improvement on patients' quality of life.

TREASURE results suggest a high probability of success for the primary outcome measure mRS in Athersys' ongoing MASTERS-2 study.

No substantial differences in safety outcomes, including mortality and life-threatening adverse events, were observed between the treatment group and the placebo group.

MASTERS-2 Study is a Phase III clinical trial conducted by Athersys in the United States, Europe, and the Asia-Pacific region to evaluate MultiStem for the treatment of ischemic stroke, with a total of 300 patients enrolled. Based on current registration information, the MASTERS-2 population is expected to be younger than the TREASURE population, with a lower average stroke severity. With a larger sample size, the probability of the trial's success is considered high.

Clinical Studies Conducted with MultiStem

MultiStem Cell Therapy (invimestrocel) is an allogeneic bone marrow-derived multipotent adult progenitor cell (MAPC) with the ability to promote tissue repair and healing in multiple ways, such as by producing therapeutic factors in response to signals of inflammation and tissue damage. MultiStem represents a unique "off-the-shelf" stem cell candidate product that can be manufactured in a scalable manner and stored frozen for several years; it does not require tissue matching or cause immunosuppression upon administration.

MultiStem Mechanism of Action

Stroke is a leading cause of death and severe disability worldwide, with significant clinical demand. Currently, there are nearly 17 million stroke patients globally, and over 2 million people in the United States, Europe, and Japan suffer from strokes each year. Ischemic stroke is the most common form, causing neurological damage due to blocked blood flow in the brain, which cuts off the supply of oxygen and nutrients, leading to long-term or permanent disability.

Currently, treatment options for patients with ischemic stroke are limited. The only available treatments are the administration of the clot-dissolving agent tPA, also known as "thrombolysis," or surgical intervention to remove the clot, both of which must be performed within hours after the stroke occurs. Due to this limited time window, only a small proportion of stroke patients receive the currently available treatments, while the majority of patients receive only supportive or "palliative" care.