Report of Placebo-Controlled Clinical Trial Evaluating MultiStem® Cell Therapy for Acute Respiratory Distress Syndrome Published in Intensive Care Medicine

Results show therapy was well-tolerated and support potential benefits in mortality, ventilator-free days, ICU-free days and quality of life outcomes

Separately, data pooled from two independent studies provide further evidence of potential clinically meaningful benefit of MultiStem as a treatment for ARDS patients

Athersys, Inc. (NASDAQ: ATHX) announced today that a manuscript reporting data from the Company’s MUST-ARDS clinical trial have been published in the peer-reviewed journal Intensive Care Medicine. MUST-ARDS was a randomized, double-blind placebo-controlled Phase 1/2 trial evaluating the safety and efficacy of MultiStem^® (invimestrocel) cell therapy in patients with acute respiratory distress syndrome (ARDS). Enrolling patients at 12 intensive care units in the United Kingdom and the U.S., the study confirmed that intravenous administration of MultiStem cell therapy was well-tolerated among critically ill patients early in the course of moderate to severe ARDS. The trial also assessed multiple efficacy endpoints, including mortality, liberation from mechanical ventilation, discharge from intensive care, and quality of life (QoL) among survivors over one full year of recovery. Mechanisms of action were further explored by comparing acute changes in plasma inflammatory and lung injury biomarkers in MultiStem-treated and placebo-treated study participants. The results of this study provided the basis for the Food and Drug Administration (FDA) to grant the Company’s ARDS program Regenerative Medicine Advanced Therapy (RMAT) and Fast Track designation. The open access publication can be found online at the following link: https://link.springer.com/content/pdf/10.1007/s00134-021-06570-4.pdf.

Highlights from the publication, including new and previously disclosed data:

• MultiStem treatment was well-tolerated in this clinical trial, with no allergic or serious adverse reactions associated with the cell therapy in any cohort through one year of follow-up;
• Notably higher median ICU-free and ventilator-free days (VFDs) among MultiStem cell recipients compared to the placebo group at the 28-day benchmark;
• Lower all-cause mortality in the MultiStem-treatment group compared to the placebo group;
• QoL outcomes, assessed by the EQ-5D-3L at days 28, 90, and 365, showed greater recovery among survivors who received MultiStem treatment compared to those who received placebo;
• Decreases in several pro-inflammatory plasma biomarkers were observed in the cell treatment group through Day 7 compared with increases among placebo recipients; and
• Similar acute plasma biomarker responses to MultiStem, including decreases in pro-inflammatory cytokines IL-1beta, TNFα, IL-6, IFN-gamma and IL-2, have been observed following treatment for ischemic stroke.

In addition (not reported in the published manuscript), preliminary analyses of the data pooled from the MUST-ARDS study and the recently completed ONE-BRIDGE study, which was conducted by Athersys’ partner, HEALIOS K.K. (Healios), in Japan, further supports potential clinically meaningful benefit of MultiStem as a treatment for ARDS patients. These pooled randomized data sets include 40 non-COVID ARDS patients treated with MultiStem cell therapy and 20 ARDS patients treated with placebo or receiving standard of care. Analysis of covariance, adjusting for baseline severity, age, and study participation, revealed an estimate of 5.4 greater (90% confidence interval 0.48-10.32; two-sided p=0.07) VFDs among MultiStem recipients compared to the control group. Similar analyses supported lower mortality in the MultiStem treatment group as well. The pooled data analyses can be found on the Company’s corporate presentation at this link: https://s23.q4cdn.com/674737627/files/11-02-2021-ATHX-Corp-Investor-Presentation.pdf.

“The MUST-ARDS study, completed before the emergence of COVID-19 as a human disease, was an important contribution to the field of cell therapy in the treatment of ARDS. The trial confirmed tolerability of MultiStem infusion in critically ill adults with severe hypoxemic respiratory failure, and often with other coincident organ failure syndromes, and revealed very encouraging signs of improved outcomes that matter to patients and their families,” commented Dr. Eric Jenkins, study co-author, Senior Medical Director and Head of Clinical Programs at Athersys.

“The results of this study, previously presented only as an oral abstract, provided the basis for the advancement of Healios’ ONE-BRIDGE ARDS trial and our own MACoVIA pivotal trial of MultiStem for the treatment of ARDS resulting from COVID and other severe infections. While the study was small, and therefore not powered to provide definitive conclusions about efficacy, the trial provided a strong foundation of safety and persuading support that MultiStem could be an effective immunomodulatory therapy for this previously untreatable and high morbidity inflammatory lung injury syndrome. These results encouraged Athersys, Healios, our clinical collaborators, and others in the field to advance cell therapy for the treatment of ARDS into confirmatory and late-stage clinical trials. It is important that these results are now available in the peer-reviewed literature. I would like to thank our co-authors, the MUST-ARDS clinical research teams, and, most importantly, the patients and families, who on their behalf chose, in their most desperate vulnerability, to contribute to the advancement of medical care for future patients,” concluded Dr. Jenkins.

There remains a strong need for a safe treatment option that can reduce the mortality of patients who develop ARDS, speed recovery, and improve the quality of life for survivors. The MUST-ARDS study has shown safety and tolerability of intravenous administration of MultiStem at doses up to 900 million cells in patients with ARDS. The study data, along with preclinical data, suggest that MultiStem may modulate multiple host responses to tissue injury simultaneously, including down-regulation of hyperinflammatory responses, stimulation of tissue repair, and restoration immune system balance, and support the rationale to conduct an additional larger size study to evaluate efficacy. The Company’s MACoVIA study is a multi-center, randomized, double-blind, placebo-controlled, Phase 2/3 trial to investigate the therapeutic efficacy of MultiStem for the treatment of pathogen-induced ARDS.

About ARDS

ARDS is a serious immunological and inflammatory condition characterized by widespread inflammation in the lungs. ARDS can be triggered by pneumonia, sepsis, trauma or other events and represents a major cause of morbidity and mortality in the critical care setting. ARDS is associated with a high mortality rate and significant sequelae among survivors. The condition prolongs ICU and hospital stays and often requires extended convalescence in the hospital and rehabilitation care settings. There are limited interventions and no effective drug treatments for ARDS. There is a large unmet need for a safe treatment that can reduced mortality and improve quality of life for those suffering with ARDS. Additionally, given the high treatment costs associated with ARDS, a successful therapy could be expected to generate significant savings for the healthcare system by reducing days on a ventilator and in the ICU.

About MultiStem^®

MultiStem^® 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 safety profile demonstrated in clinical studies, MultiStem therapy could provide a meaningful benefit to patients, including those suffering from serious diseases and conditions with unmet medical need.

About Athersys

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. The Company is developing its MultiStem^® cell therapy product, a patented, adult-derived "off-the-shelf" stem cell product, initially for disease indications in the neurological, inflammatory and immune, cardiovascular and other critical care indications and has several ongoing clinical trials evaluating this potential regenerative medicine product. Athersys has forged strategic partnerships and a broad network of collaborations to further advance the MultiStem cell therapy toward commercialization. More information is available at www.athersys.com. Follow Athersys on Twitter at www.twitter.com/athersys.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that involve risks and uncertainties. These forward-looking statements relate to, among other things, the expected timetable for development of our product candidates, our growth strategy, and our future financial performance, including our operations, economic performance, financial condition, prospects, and other future events. We have attempted to identify forward-looking statements by using such words as “anticipates,” “believes,” “can,” “continue,” “could,” “estimates,” “expects,” “intends,” “may,” “plans,” “potential,” “should,” “suggest,” “will,” or other similar expressions. These forward-looking statements are only predictions and are largely based on our current expectations. A number of known and unknown risks, uncertainties, and other factors could affect the accuracy of these statements. Some of the more significant known risks that we face are the risks and uncertainties inherent in the process of discovering, developing, and commercializing products that are safe and effective for use as therapeutics, including the uncertainty regarding market acceptance of our product candidates and our ability to generate revenues. The following risks and uncertainties may cause our actual results, levels of activity, performance, or achievements to differ materially from any future results, levels of activity, performance, or achievements expressed or implied by these forward-looking statements: our ability to raise capital to fund our operations, including but not limited to, the timing and nature of results from MultiStem clinical trials, including the MASTERS-2 Phase 3 clinical trial evaluating the administration of MultiStem for the treatment of ischemic stroke, and the Healios TREASURE and ONE-BRIDGE clinical trials in Japan evaluating the treatment in stroke and ARDS patients, respectively, including the timing of the release of data by Healios from its clinical trials, which could be delayed by, among other things, the regulatory process with the PMDA; the success of our MACOVIA clinical trial evaluating the administration of MultiStem for the treatment of COVID-19 induced ARDS, and the MATRICS-1 clinical trial being conducted with The University of Texas Health Science Center at Houston evaluating the treatment of patients with serious traumatic injuries; the impact of the COVID-19 pandemic on our ability to complete planned or ongoing clinical trials; the possibility that the COVID-19 pandemic could delay clinical site initiation, clinical trial enrollment, regulatory review and the potential receipt of regulatory approvals, payment of milestones under our license agreements and commercialization of one or more of our product candidates, if approved; the availability of product sufficient to meet commercial demand shortly following any approval, such as in the case of accelerated approval for the treatment of COVID-19 induced ARDS; the impact on our business, results of operations and financial condition from the ongoing and global COVID-19 pandemic, or any other pandemic, epidemic or outbreak of infectious disease in the United States; the possibility of delays in, adverse results of, and excessive costs of the development process; our ability to successfully initiate and complete clinical trials of our product candidates; the impact of the COVID-19 pandemic on the production capabilities of our contract manufacturing partners and our MultiStem trial supply chain; the possibility of delays, work stoppages or interruptions in manufacturing by third parties or us, such as due to material supply constraints, contamination, operational restrictions due to COVID-19 or other public health emergencies, labor constraints, regulatory issues or other factors which could negatively impact our trials and the trials of our collaborators; uncertainty regarding market acceptance of our product candidates and our ability to generate revenues, including MultiStem cell therapy for neurological, inflammatory and immune, cardiovascular and other critical care indications; changes in external market factors; changes in our industry’s overall performance; changes in our business strategy; our ability to protect and defend our intellectual property and related business operations, including the successful prosecution of our patent applications and enforcement of our patent rights, and operate our business in an environment of rapid technology and intellectual property development; our possible inability to realize commercially valuable discoveries in our collaborations with pharmaceutical and other biotechnology companies; our ability to meet milestones and earn royalties under our collaboration agreements, including the success of our collaboration with Healios; our collaborators’ ability to continue to fulfill their obligations under the terms of our collaboration agreements and generate sales related to our technologies; the success of our efforts to enter into new strategic partnerships and advance our programs, including, without limitation, in North America, Europe and Japan; our possible inability to execute our strategy due to changes in our industry or the economy generally; changes in productivity and reliability of suppliers; the success of our competitors and the emergence of new competitors; and the risks mentioned elsewhere in our Annual Report on Form 10-K for the year ended December 31, 2020 under Item 1A, “Risk Factors” and our other filings with the SEC. You should not place undue reliance on forward-looking statements contained on our website and/or on our accounts on Twitter, Facebook, LinkedIn or other social media platforms, and we undertake no obligation to publicly update forward-looking statements, whether as a result of new information, future events or otherwise.

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