Isoquercetin

Paris, 8 July 2024, 8am CET AB Science SA (Euronext - FR0010557264 - AB) today announces the results of a Phase 2 study evaluating masitinib in COVID-19. This randomized (1:1), open-label, phase 2 study (AB20001) was designed to evaluate the safety and efficacy of masitinib plus isoquercetin in hospitalized patients with moderate COVID-19 (WHO 7-point ordinal scale level 4) or severe COVID-19 (level 5). The study initially planned to recruit 200 patients (over 18 years of age with no upper age limit). The primary objective was to improve the clinical status of patients after 15 days of treatment, as measured by the WHO 7-point ordinal scale. Following a DSMB recommendation, decision was taken to continue the study only in level 4 patients (i.e. hospitalized patients with oxygen supply <6 L/min with SpO2 maintained ≥92%). The study could not recruit the planned 200 patients. The decision was therefore taken to stop inclusion after 95 patients were randomized. The objective was to detect a trending treatment effect with 95 patients that would translate into a significant effect when simulating the same effect with the planned enrolment of 200 patients. If this objective was reached, then the conclusion would be that it is worth continuing to evaluate masitinib as an agent in the treatment of covid in patients hospitalized with moderate need of oxygen. The study showed an odds ratio of 2.4 in favor of the treatment arm after 15 days of treatment, superior to the odds ratio of 2.2 initially hypothesized, with p=0.038 simulated with 200 patients and p=0.072 detected with 95 patients recruited. Sensitivity analyses at day 12, 13 and 14 with 95 patients recruited displayed a p-value of respectively p=0.016, 0.019, 0.018 and odds ratio 3.2, 3.2 and 3.4. This was due to improvement of certain placebo patients at day 15 but not before. The safety was in line with the known safety pro masitinib. Professor Olivier Hermine, MD, President of the Scientific Committee of AB Science and member of the Académie des Sciences in France said: “This result confirms the anti-inflammatory activity of masitinib, by controlling activated macrophages and mast cells involved in COVID. In addition, several publications highlighted the capacity of masitinib to act as an indirect broad antiviral agent against COVID. With this result, masitinib can be considered a drug of choice to be evaluated in the context of a future pandemic”. Alain Moussy, co-founder and CEO of AB Science said: “We are thankful to the European Investment Bank for having funded this development of masitinib in COVID, and to our partner Quercegen for having proposed to combine masitinib with isoquercetin. This result warrants further evaluation and we will discuss such opportunity with public entities or private partners”. About AB Science Founded in 2001, AB Science is a pharmaceutical company specializing in the research, development and commercialization of protein kinase inhibitors (PKIs), a class of targeted proteins whose action are key in signaling pathways within cells. Our programs target only diseases with high unmet medical needs, often lethal with short term survival or rare or refractory to previous line of treatment. AB Science has developed a proprietary portfolio of molecules and the Company’s lead compound, masitinib, has already been registered for veterinary medicine and is developed in human medicine in oncology, neurological diseases, inflammatory diseases and viral diseases. The company is headquartered in Paris, France, and listed on Euronext Paris (ticker: AB). Further information is available on AB Science’s website: . Forward-looking Statements - AB Science This press release contains forward-looking statements. These statements are not historical facts. These statements include projections and estimates as well as the assumptions on which they are based, statements based on projects, objectives, intentions and expectations regarding financial results, events, operations, future services, product development and their potential or future performance. These forward-looking statements can often be identified by the words "expect", "anticipate", "believe", "intend", "estimate" or "plan" as well as other similar terms. While AB Science believes these forward-looking statements are reasonable, investors are cautioned that these forward-looking statements are subject to numerous risks and uncertainties that are difficult to predict and generally beyond the control of AB Science and which may imply that results and actual events significantly differ from those expressed, induced or anticipated in the forward-looking information and statements. These risks and uncertainties include the uncertainties related to product development of the Company which may not be successful or to the marketing authorizations granted by competent authorities or, more generally, any factors that may affect marketing capacity of the products developed by AB Science, as well as those developed or identified in the public documents published by AB Science. AB Science disclaims any obligation or undertaking to update the forward-looking information and statements, subject to the applicable regulations, in particular articles 223-1 et seq. of the AMF General Regulations. For additional information, please contact: AB Science Financial Communication & Media Relations investors@ab-science.com Attachment CP Covid Results vENG VF