27 March 2023 - - US-based cell therapy and regenerative medicine company Athersys, Inc. (NASDAQ: ATHX) has announced planned amendments to its MASTERS-2 clinical trial protocol following a Type B meeting with the US Food & Drug Administration.

Held on March 21, 2023, the meeting addressed Athersys' proposed modifications that seek to establish primary and secondary endpoints that it believes best reflect the full potential benefit of MultiStem treatment for patients with acute, moderate-to-severe ischemic stroke as well as the evolving standard of care.

Following a meeting Athersys convened in November 2022 of leading stroke experts, regulatory specialists, and statisticians to discuss potential changes, Athersys proposed four modifications to its ongoing pivotal Phase 3 MASTERS-2 clinical trial protocol, all of which were accepted by the FDA.

After finalizing agreement around the statistical approach, Athersys will implement the following amendments to the MASTERS-2 protocol:

Athersys will change the timing of the primary endpoint assessed by shift analysis in modified Rankin Scale score to Day 365, from Day 90 previously.

Athersys will retain shift analysis in mRS score at Day 90 as a key secondary endpoint, along with other revised secondary endpoints.

Athersys will remove eligibility caps on concomitant reperfusion therapy (e.g., tPA, MR imaging or tPA+MR imaging) to ensure the final study population is reflective of current standard of care in the population eligible for this therapy.

Athersys may elect to have an independent statistician conduct an interim analysis to assess potential sample size adjustment. MASTERS-2 currently plans to enroll 300 patients and enrollment, as previously communicated, is >50% complete.

Athersys was previously granted Regenerative Medicine Advanced Therapy, Fast Track designation and Special Protocol Assessment agreement for the use of MultiStem in the treatment of ischemic stroke.

These designations enable sponsors to work closely with the FDA and receive guidance on expediting advancement of designated programs.

MultiStem (invimestrocel) cell therapy is a patented regenerative medicine product in clinical development that has shown the ability to promote tissue repair and healing in a variety of ways, such as through the production of therapeutic factors in response to signals of inflammation and tissue damage.

MultiStem therapy's potential for multidimensional therapeutic impact distinguishes it from traditional biopharmaceutical therapies focused on a single mechanism of benefit.

The therapy represents a unique "off-the-shelf" stem cell product that can be manufactured in a scalable manner, may be stored for years in frozen form, and is administered without tissue matching or the need for immune suppression.

Based upon its efficacy profile, its novel mechanisms of action, and a favorable and consistent tolerability demonstrated in clinical studies, we believe that MultiStem therapy could provide a meaningful benefit to patients, including those suffering from serious diseases and conditions with unmet medical need.

Athersys is a biotechnology company engaged in the discovery and development of therapeutic product candidates designed to extend and enhance the quality of human life.