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Primary endpoint met with ABX464 demonstrating good safety and tolerability profile with 50mg once daily oral administration A statistically significant difference (p < 0.03) was met on key efficacy endpoint ACR20 [1] in the PP [2] population with 60% of ABX464 patients dosed with 50mg reaching that endpoint versus 22% in the placebo group Other key efficacy endpoints (ACR50, ACR70, DAS28-CRP [3] , CDAI [4] ) as well as biological markers (CRP, miR-124, IL-6) showed favorable differences with 50mg ABX464 over placebo Abivax is preparing to start a clinical phase 2b program in rheumatoid arthritis in early 2022 Given the demonstrated safety and efficacy of ABX464 in rheumatoid arthritis and ulcerative colitis, Abivax is exploring additional programs in chronic inflammatory indications Abivax to host webcast on Wednesday June 23, 2021 at 2:00 pm CEST (8:00 am EST) PARIS, FRANCE / ACCESSWIRE / June 23, 2021 / Abivax SA (Euronext Paris: FR0012333284 - ABVX), a clinical-stage biotechnology company developing novel therapies that modulate the immune system to treat chronic inflammatory diseases, viral infections, and cancer, announces excellent top-line results of the induction phase of its phase 2a clinical study of ABX464 administered in combination with methotrexate (MTX) for the treatment of active moderate to severe rheumatoid arthritis (RA). 60 patients who had either an inadequate response to methotrexate and/or TNFα inhibitors participated in the study. The primary endpoint of this study, safety and tolerability, was met with 50mg ABX464 once daily demonstrating a good safety and tolerability profile in the overall patient population during the 12-week induction phase. Although the sample size of this study was not powered to show efficacy, the 50mg group already showed statistically significant differences for the key secondary endpoint ACR20 compared to placebo at week 12 in the Per Protocol population. The ACR20 is the key primary efficacy endpoint required by the FDA for licensure of new drugs in rheumatoid arthritis. Based on these results, Abivax is preparing to start a clinical phase 2b program in RA in early 2022. [5] ABX464 is a small molecule for once-daily administration with a first-in-class mechanism of action, centered around the upregulation of the anti-inflammatory microRNA, miR-124. ABX464 was already shown to be efficacious and safe in phase 2a and phase 2b clinical studies for the treatment of ulcerative colitis (UC). Prof. Claire Daien, M.D., Ph.D., rheumatologist at the University Hospital at Montpellier and principal investigator of the study, said: "I am excited about these positive clinical phase 2a results. 50mg once daily oral treatment with ABX464 shows to be well tolerated and efficacious in patients in the induction study. This is remarkable, as these top-line efficacy results are at par with currently available treatments. Even if the standard of care made some progress during the past years, too many patients still do not respond or lose responsiveness to available drugs, and new molecules with a different mechanism of action, like ABX464, are needed. Therefore, ABX464 should move to phase 2b testing as quickly as possible." Prof. Hartmut J. Ehrlich, M.D., CEO of Abivax, added: "ABX464 has already shown good safety and robust, sustained efficacy in our phase 2a and phase 2b induction and maintenance clinical trials for the treatment of ulcerative colitis. Combined with the phase 2a results in RA, we believe that ABX464 may have an important potential as a novel, highly differentiated anti-inflammatory therapeutic agent across various inflammatory indications. Just as ulcerative colitis and Crohn's disease, rheumatoid arthritis is an irreversible, debilitating, and systemic autoimmune disease that often requires aggressive treatment to control it. This disease represents a major burden for the millions of affected patients, their families and for healthcare systems worldwide and there is an urgent need for new efficacious and well tolerated therapeutic management options." 50mg once daily oral administration of ABX464 is safe and well tolerated by RA patients with previous inadequate response to MTX and/or to one or more anti-tumor necrosis factor alpha (TNFα) biological therapeutics and shows very promising efficacy results The clinical phase 2a study was designed to evaluate the safety, tolerability and preliminary efficacy of two oral dose-levels of ABX464 administered once daily (50mg and 100mg), in combination with methotrexate (MTX). 60 patients who had an inadequate response to MTX and/or to one or more anti-tumor necrosis factor alpha (TNFα) biological therapeutics participated in this randomized, double-blind, placebo-controlled trial. Patients received ABX464 (50mg or 100mg) or placebo during the 12-week induction treatment phase. The study was conducted in 21 study centers across four European countries (France, Belgium, Poland and Hungary). The treatment groups were well balanced in terms of disease severity as well as patient demographics. The primary endpoint of the study was met with 50mg ABX464 once daily being safe and well tolerated during the 12-week induction phase. No deaths or malignancies were reported in the study. One serious adverse event (SAEs) was reported in the placebo group and one in the 100mg dose group, while no SAE was reported in the 50mg dose group. 3 patients in the 50mg group, 12 patients in the 100mg group and 1 patient in the placebo group prematurely discontinued the study. An increased incidence of largely mild to moderate gastrointestinal adverse events in the 100mg treatment group is likely due to an overlapping side effect profile with methotrexate (MTX), leading to a higher drop-out rate of patients, especially as it refers to nausea and emesis. Therefore, the 100mg dose will not be considered for future clinical development of ABX464 in rheumatoid arthritis. The nature of these adverse events is consistent with what has been observed in more than 800 subjects who have so far been treated in other clinical trials with ABX464 across different indications. Secondary efficacy endpoints included the proportion of patients achieving ACR20/50/70 responses, change from baseline in DAS28-CRP low disease activity (DAS28-CRP <= 3.2) and Clinical Disease Activity Index (CDAI). * P < 0.03 - Statistical tests were only conducted for ACR20 as part of topline results + PP Per Protocol population set for ACR levels In addition, a DAS28-CRP remission (DAS-CRP < 2.6) has been reported in 19% of patients dosed with 50mg ABX464 compared to 5% in the placebo group (ITT). Regarding biomarkers, a significant upregulation of miR-124 expression was observed for every patient dosed with ABX464, and a decrease in IL-6 blood levels was observed in both active dose groups compared to placebo. Patients who completed the induction study could roll over into a two-year open-label maintenance study to evaluate the long-term safety and efficacy of 50mg once daily oral ABX464 in RA. One-year data from this study will become available in Q1 2022. Epidemiology, unmet medical needs and market size in rheumatoid arthritis In 2020, there were an estimated 3.8M diagnosed cases of rheumatoid arthritis in G7 countries (US, France, Germany, Italy, Spain, UK and Japan). Despite the existing therapeutic options for RA including biologic disease-modifying antirheumatic drugs 74% of patients report dissatisfaction with their treatment plans mandates more patients-centered therapeutic options which are safe and easy to administer. [6] The total market size in RA is USD 20.4B annually, based on 2020 pharmaceutical sales estimates for rheumatoid arthritis in these countries, estimated to grow to USD 22.9B by 2025. The currently accessible market for ABX464 in IBD and RA is estimated to grow to USD 48B by 2025, while the overall chronic inflammation market is estimated to exceed USD 110B at that time. [7] ABX464 phase 3 in UC, phase 2b in Crohn's disease and phase 2b clinical trial in rheumatoid arthritis (RA) A pivotal phase 3 clinical trial program in UC is expected to be initiated by the end of 2021. A dose ranging, randomized, placebo-controlled pivotal phase 2b trial in Crohn's disease patients is expected to be initiated before the end of the year. A phase 2b dose ranging study in RA is expected to start in early 2022. Based on the encouraging data in UC and RA, Abivax is planning to explore additional chronic inflammatory indications in the near future. About ABX464 [8] [9] ABX464 is a highly differentiated oral drug candidate, with a novel mechanism of action based on the upregulation of a single microRNA (miR-124) with potent anti-inflammatory properties. ABX464 was shown to exert its anti-inflammatory effects through binding to the cap binding complex (CBC), which sits at the 5' end of every RNA molecule in the cell. By binding to the CBC, ABX464 reinforces the biological functions of CBC in cellular RNA biogenesis. Specifically, ABX464 enhances the selective splicing of a single long non-coding RNA to generate the anti-inflammatory microRNA, miR-124, which downregulates pro-inflammatory cytokines and chemokines like TNF-α, IL-6, MCP-1 and IL-17, as well as Th17+ cells thereby "putting a brake" on inflammation and suggesting broad potential as a novel anti-inflammatory therapeutic agent. A seven- to ten-fold increase in miRNA-124 levels was observed in colorectal biopsies of UC patients treated with ABX464. ABX464 does not impact the splicing of cellular genes. Ulcerative colitis phase 2b top-line results as well as phase 2a induction and maintenance data after one and two years of treatment were previously reported. ***** Investor webcast on phase 2a study results Abivax will host a webcast on Wednesday, June 23, 2021 at 2:00 pm CEST (8:00 am EST) , to present the top-line data of its ABX464 phase 2a clinical study in RA. Following the formal presentation, Abivax senior management, will be available to answer questions. To participate in the webcast, please follow the weblink: ***** About Abivax () Abivax, a clinical stage biotechnology company, is developing novel therapies that modulate the physiological inflammation and immunological pathways to treat patients with chronic inflammatory diseases, viral infections, and cancer. Abivax is listed on Euronext compartment B (ISIN: FR0012333284 - Mnémo: ABVX). Based in Paris and Montpellier, Abivax has two drug candidates in clinical development, ABX464 to treat severe inflammatory diseases, and ABX196 to treat hepatocellular carcinoma. More information on the company is available at . Follow us on Twitter @ABIVAX_. Contacts Abivax Communications Regina Jehle regina.jehle@abivax.com +33 6 24 50 69 63 Investors LifeSci Advisors Chris Maggos chris@lifesciadvisors.com +41 79 367 6254 Press Relations & Investors Europe MC Services AG Anne Hennecke anne.hennecke@mc-services.eu +49 211 529 252 22 Public Relations France Actifin Ghislaine Gasparetto ggasparetto@actifin.fr +33 6 21 10 49 24 Public Relations France DGM Conseil Thomas Roborel de Climens thomasdeclimens@dgm-conseil.fr +33 6 14 50 15 84 Public Relations USA Rooney Partners LLC Marion Janic mjanic@rooneyco.com +1 212 223 4017 DISCLAIMER This press release contains forward-looking statements, forecasts and estimates (including patient recruitment) with respect to certain of the Company's programs. Although the Company believes that its forward-looking statements, forecasts and estimates are based on assumptions and assessments of known and unknown risks, uncertainties and other factors that have been deemed reasonable, such forward-looking statements, forecasts and estimates are subject to a number of risks and uncertainties that could cause actual results to differ materially from those anticipated in such forward-looking statements, forecasts and estimates. A description of these risks, contingencies and uncertainties can be found in the documents filed by the Company with the French Autorité des Marchés Financiers pursuant to its legal obligations including its registration document (Document d'Enregistrement Universel). Special consideration should be given to the potential hurtles of clinical and pharmaceutical development including further assessment by the company and regulatory agencies and ethics committees of preclinical, pharmacokinetic, carcinogenicity, toxicity, CMC, clinical data, Furthermore, these forward-looking statements, forecasts and estimates are only as of the date of this press release. Readers are cautioned not to place undue reliance on these forward-looking statements. Abivax disclaims any obligation to update these forward-looking statements, forecasts or estimates to reflect any subsequent changes that the Company becomes aware of, except as required by law. This press release is for information purposes only, and the information contained herein does not constitute either an offer to sell, or the solicitation of an offer to purchase or subscribe securities of the Company in any jurisdiction, in particular in France. Similarly, it does not give and should not be treated as giving investment advice. It has no connection with the investment objectives, financial situation or specific needs of any recipient. It should not be regarded by recipients as a substitute for exercise of their own judgement. All opinions expressed herein are subject to change without notice. The distribution of this document may be restricted by law in certain jurisdictions. Persons into whose possession this document comes are required to inform themselves about and to observe any such restrictions. [1] The American College of Rheumatology ACR score measures the efficacy of treatments for rheumatoid arthritis patients. The ACR20/50/70 measures a 20/50/70% improvement in the tenderness and swelling in designated joints and a 20/50/70% improvement in at least 3 of the 5 following measures: investigator's and patient's reported global assessment of disease scales, patient's reported pain scale, CRP level, healthy assessment questionnaire. [2] PP: Per protocol data [3] DAS28-CRP-Disease Activity Score for 28 joints - C reactive Protein [4] The Clinical Disease Activity Index (CDAI) is a composite index based on the tenderness and swelling in designated 28 joints and on investigator's and patient's reported global assessment of disease scales. [5] Future clinical development including phase 2b design and initiation is subject to assessment of the overall preclinical, CMC, toxicology, clinical efficacy and safety data of ABX464 by EMA, FDA and other regulatory authorities. These top-line results have not yet been reviewed by regulatory authorities. [6] Radawski C, Genovese MC, Hauber B, et al. Patient perceptions of unmet medical need In rheumatoid arthritis: a cross-sectional survey in the USA. Rheumatol Ther. 2019;6:461-471. [7] Source: Informa [8] J. Tazi et al.: Specific and selective induction of miR-124 in immune cells by the quinoline ABX464: a transformative therapy for inflammatory diseases, Drug Discovery Today, Volume 26, Issue 4, April 2021, Pages 1030-1039 [9] S. Vermeire et al.: Induction and long-term follow-up with ABX464 for moderate-to-severe ulcerative colitis: Results of phase 2a trial, Gastroenterology, March 2021 SOURCE: ABIVAX View source version on accesswire.com:

TORONTO and CAMBRIDGE, Mass., May 12, 2021 (GLOBE NEWSWIRE) -- ProMIS Neurosciences, Inc. (TSX: PMN); (OTCQB: ARFXF), a biotechnology company focused on the discovery and development of antibody therapeutics selectively targeting toxic oligomers implicated in the development of neurodegenerative diseases, today announced the appointment of Rudolph Tanzi, Ph.D, as Chair of the Company’s scientific advisory board (SAB). Dr. Tanzi is the Joseph P. and Rose F. Kennedy Professor of Neurology at Harvard University and Vice-Chair of Neurology, Director of the Genetics and Aging Research Unit, and Co-Director of the Henry and Allison McCance Center for Brain Health at Massachusetts General Hospital. “Dr. Rudy Tanzi has been a valuable member of our scientific advisory board for years, and we are thrilled that he has agreed to accept the Chairman’s role as we work to expand our portfolio of potential best in class products,” stated Eugene Williams, ProMIS Executive Chairman. “As an expert neuroscientist in the field of neurodegenerative disorders, with over three decades of outstanding research accomplishments in Alzheimer’s, ALS, and other diseases, Dr. Tanzi can help us fully develop the potential of our portfolio, capitalizing on the recent strong financial support from a Boston-based group of investors.” Commenting on the appointment, Dr. Tanzi stated: “I am delighted to take on this new role with the ProMIS SAB. I have been impressed with the progress of the scientific portfolio, based on ProMIS’ unique technology platform, that continues to create potential antibody therapies highly selective for the toxic forms of proteins. I look forward to advising ProMIS Neurosciences as the Company progresses its innovative programs into the clinic, including PMN310 in Alzheimer’s disease.” Dr. Rudolph Tanzi is a neuroscientist and geneticist with scientific expertise in Alzheimer’s disease (AD) and brain health. He is one of the world’s leading scientists in research aimed at preventing and treating Alzheimer’s disease. His research studies and books have also focused on preserving and promoting brain health. In his research achievements, Dr. Tanzi served on the team that was the first to find a disease gene (Huntington’s disease) using human genetic markers, helping to launch the field of neurogenetics. Dr. Tanzi went on to identify all three early-onset familial AD genes: the amyloid precursor protein and presenilins 1 and 2. As leader of the Cure Alzheimer’s Fund Alzheimer’s Genome Project, he has identified several other AD-related genes, including the first shown to causing neuroinflammation in AD (CD33). Dr. Tanzi also uncovered the Wilson’s disease gene and several other neurological disease-related genes. Dr. Tanzi and his team have used AD genes and human stem cells to create “Alzheimer’s-in-a-Dish” - a three-dimensional human stem cell-derived neural culture system that was the first to recapitulate both pathological hallmarks of AD: plaques and tangles. This model has made drug screening for AD considerably faster and more efficient. Using this system, Dr. Tanzi has developed several promising therapeutic candidates for AD including gamma secretase modulators aimed at beta-amyloid pathology. Most recently, Dr. Tanzi and his team have discovered that beta-amyloid may play a role in the innate immune system of the brain operating as an anti-microbial peptide, suggesting a possible role for infection in the etiology and pathogenesis of AD. Dr. Tanzi has published over 600 research papers and has received the highest awards in his field, including the Metropolitan Life Foundation Award, Potamkin Prize, Ronald Reagan Award, Silver Innovator Award, and the Smithsonian American Ingenuity Award, the top national award for invention and innovation. He serves on dozens of editorial boards and scientific advisory boards and was named to TIME magazine’s list of TIME100 Most Influential People in the World. He also co-authored the books Decoding Darkness, and the three international bestsellers, Super Brain, Super Genes, and The Healing Self. Dr. Tanzi is also a musician who professionally records and performs (keyboards), most recently with Joe Perry and Aerosmith. About the ProMIS Scientific Advisory BoardThe ProMIS SAB brings together a multidisciplinary group of specialists in Alzheimer's disease and neurodegenerative disease along with experts in neurotoxic, prion-like misfolded proteins. In addition to Dr. Tanzi, the current members of the Company’s SAB include: About ProMIS Neurosciences, Inc.ProMIS Neurosciences, Inc. is a development stage biotechnology company focused on discovering and developing antibody therapeutics selectively targeting toxic oligomers implicated in the development and progression of neurodegenerative diseases, in particular Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS) and Parkinson’s disease (PD). The Company’s proprietary target discovery engine is based on the use of two complementary techniques. The Company applies its thermodynamic, computational discovery platform -ProMIS™ and Collective Coordinates - to predict novel targets known as Disease Specific Epitopes on the molecular surface of misfolded proteins. Using this unique approach, the Company is developing novel antibody therapeutics for AD, ALS and PD. ProMIS is headquartered in Toronto, Ontario, with offices in Cambridge, Massachusetts. ProMIS is listed on the Toronto Stock Exchange under the symbol PMN, and on the OTCQB Venture Market under the symbol ARFXF. For further information about ProMIS Neurosciences, please consult the Company’s website at: Follow us on TwitterLike us on LinkedIn For Investor Relations please contact:Alpine Equity AdvisorsNicholas Rigopulos, Presidentnick@alpineequityadv.comTel. 617 901-0785 The TSX has not reviewed and does not accept responsibility for the adequacy or accuracy of this release. This information release contains certain forward-looking information. Such information involves known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements to be materially different from those implied by statements herein, and therefore these statements should not be read as guarantees of future performance or results. All forward-looking statements are based on the Company's current beliefs as well as assumptions made by and information currently available to it as well as other factors. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. Due to risks and uncertainties, including the risks and uncertainties identified by the Company in its public securities filings, actual events may differ materially from current expectations. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. A photo accompanying this announcement is available at