PD-1 x IL-7

Nantes, France – July 1st, 2024 – 7:30 am CET – OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) today announced the publication of an article on latest preclinical efficacy data on the use of its anti-IL-7 receptor (IL-7R A&io) antagonist Lusvertikimab (OSE-127) for the treatment of B- and T-Cell Acute Lymphoblastic Leukemia (B- and T-ALL) in ‘Blood’, a peer-reviewed medical journal published by the American Society of Hematology. The preclinical data on Lusvertikimab published in ‘Blood’ was generated from a collaborative research program between OSE Immunotherapeutics and the University Medical Center Schleswig-Holstein in Kiel (Germany). This collaboration is using patient-derived samples and in-vivo xenograft models to evaluate the therapeutic potential of anti-IL-7R antagonist Lusvertikimab in targeting and blocking the high and dysregulated IL-7R-expression observed in nearly 85% of B- or T-Acute Lymphoblastic Leukemia (ALL) patients. Pr. Denis Schewe (newly appointed Head of Pediatric Hematology/Oncology, University Hospital Dresden and National Center for Tumor Diseases, Partner Site Dresden, and formerly from the University Medical Center Schleswig-Holstein of Kiel) and Dr. Lennart Lenk (Department of Pediatrics I, Christian-Albrechts University Kiel and University Medical Center Schleswig-Holstein, Kiel), leading the research program in collaboration with OSE Immunotherapeutics, comment: “Treatment options for T-ALL remain very limited and there is an urgent need for novel immunotherapy approaches to reduce toxicity and to target relapsed or refractory disease in ALL patients. Through its dual mode of action comprising both IL-7R signaling blockade and antibody-dependent cellular phagocytosis induction, Lusvertikimab may represent a promising novel immunotherapy option for CD127 positive ALL patients, particularly in combination with polychemotherapy standard of care. When translated into the clinic, Lusvertikimab could significantly improve ALL-therapy and the outcome of relapsed/refractory disease.” Nicolas Poirier, Chief Executive Officer of OSE Immunotherapeutics, concludes: “We are very pleased with this publication on Lusvertikimab in ‘Blood’, a high-level journal within the field of hematology whose manuscripts are reviewed by prominent specialists. Novel targeted immunotherapy options are urgently needed for B-ALL and T-ALL patients and we are happy to collaborate with the research leaders in hematology from the University of Kiel to face this clinical challenge.” The abstract, titled: “The IL-7R antagonist Lusvertikimab reduces leukemic burden in xenograft-ALL via antibody-dependent cellular phagocytosis” reported that IL-7R immunotherapy with Lusvertikimab shows significant in vivo efficacy in preclinical models using samples from B-ALL and T-ALL. Mechanistically, Lusvertikimab targeted ALL cells via a dual mode: On one hand it blocks IL-7 receptor signaling and hence block proliferative and pro-survival signals induced by Interleukin-7. In parallel, it induces leukemic cells elimination by macrophages (antibody-dependent phagocytosis), in particular with strong correlation with the level of IL-7R surface expression on leukemic cells. About Acute Lymphoblastic Leukemia (ALL) Acute lymphoblastic leukemia (ALL) is a heterogeneous group of lymphoid disorders resulting from clonal proliferation of immature lymphocytes of B-cell (85%) or T-cell (15%) lineages (3) in the blood, bone marrow, and other lymphoid organs. Although it is one of the most common cancers in children, accounting for approximately 25% of all childhood cancer diagnoses among children under 15 years of age (4), adults can also develop ALL. About 40% cases of ALL diagnosed are in adults and among them about 50% present refractory disease or undergo relapse under current conventional therapies (4). The American Cancer Society estimates that almost 6,660 new cases of ALL will be diagnosed in the United States in 2022(5). In Europe, 7,000 cases of ALL are diagnosed each year (6). The number of patients in Japan was reported to be about 5,000 in a survey by the Japanese MHLW in 2017. The number of diagnosed incident cases of acute lymphocytic leukemia (ALL) in Europe, US, Japan and China is estimated to achieve 26,482 cases in 2029(7). (1) ASH Publication – Blood (2022) 140 (Supplement 1): 1045 - 1047 (2) Lennart Lenk, PhD, Irène Baccelli, PhD, Dorothee Winterberg, PhD, Anna Dietterle, Frédérique Corallo, MD, Julien Taurelle, Emma Narbeburu*, Anna Laqua, PhD, Beat Bornhauser, PhD, Jean-Pierre Bourquin, MD, PhD, Fotini Vogiatzi, PhD, Martin Schrappe, MD, Gunnar Cario, Monika Brüggemann, MD, Nicolas Poirier, PhD and Denis Martin Schewe, MD (3)DeVita, Jr. VT, Hellman S, Rosenberg SA, eds.; Cancer: Principles and Practice of Oncology, 10th ed.; Lippincott-Raven, Philadelphia, PA; 2014. (4) Childhood Acute Lymphoblastic Leukemia Treatment (PDQ®)–Health Professional Version, accessed October 2022 (5) American Cancer Society. Key 2022 Statistics for Acute Lymphocytic Leukemia (ALL). Available at: ., accessed October 2022 (6) Gatta G, van der Zwan JM, Casali P, et al. Rare cancers are not so rare: The rare cancer burden in Europe. Eur. J. Cancer. 2011; 47: 2493-2511. (7) Global Data ABOUT OSE IMMUNOTHERAPEUTICS OSE Immunotherapeutics is a biotech company dedicated to developing first-in-class assets in immuno-oncology (IO) and immuno-inflammation (I&I). The Company’s current well-balanced first-in-class clinical pipeline includes: Tedopi® (immunotherapy activating tumor specific T-cells, off-the-shelf, neoepitope-based): this cancer vaccine is the Company’s most advanced product; positive results from the Phase 3 trial (Atalante 1) in Non-Small Cell Lung Cancer patients in secondary resistance after checkpoint inhibitor failure. Other Phase 2 trials, sponsored by clinical oncology groups, of Tedopi® in combination are ongoing in solid tumors. OSE-279 (anti-PD1): first positive results in the ongoing Phase 1/2 in solid tumors. OSE-127 - lusvertikimab (humanized monoclonal antibody antagonist of IL-7 receptor); ongoing Phase 2 in Ulcerative Colitis (sponsor OSE Immunotherapeutics); ongoing preclinical research in leukemia (OSE Immunotherapeutics). FR-104/VEL-101 (anti-CD28 monoclonal antibody): developed in partnership with Veloxis Pharmaceuticals, Inc. in transplantation; ongoing Phase 1/2 in renal transplant (sponsor Nantes University Hospital); successful Phase 1 in the US (sponsor Veloxis Pharmaceuticals, Inc.). Anti-SIRPα monoclonal antibody developed in partnership with Boehringer Ingelheim in advanced solid tumors and cardiovascular-renal-metabolic diseases (CRM); positive Phase 1 dose escalation results in monotherapy and in combination; Phase 2 in CRM diseases planned to be initiated end of 2024. ABBV-230 (ChemR23 agonist mAb) developed in partnership with AbbVie in chronic inflammation. OSE Immunotherapeutics expects to generate further significant value from its three proprietary drug discovery platforms, which are central to its ambitious goal to deliver next-generation first-in-class immunotherapies: Pro-resolutive mAb platform focused on targeting and advancing inflammation resolution and optimizing the therapeutic potential of targeting Neutrophils and Macrophages in I&I. ABBV-230 (licensed to AbbVie) is the first candidate generated by the platform, additional discovery programs ongoing on new pro-resolutive GPCRs. Myeloid Checkpoint platform focused on optimizing the therapeutic potential of myeloid cells in IO by targeting immune regulatory receptors expressed by Macrophages and Dendritic cells. BI 765063 and BI 770371 (licensed to Boehringer Ingelheim) are the most advanced candidates generated by the platform. Ongoing additional discovery programs, in particular with positive preclinical results obtained in monotherapy with new anti-CLEC-1 mAbs. BiCKI® Platform is a bifunctional fusion protein platform built on the key backbone component of anti-PD1 combined with a new immunotherapy target to increase anti-tumor efficacy by “cis-potentiating” tumor-specific T cells. A first program has been acquired by Boehringer Ingelheim. mRNA Therapeutic platform allows local delivery into the inflammatory site of innovative immunotherapies encoded by RNA to locally controls and/or suppress immune responses and inflammation. Additional information about OSE Immunotherapeutics assets is available on the Company’s website: Follow us on Twitter and LinkedIn Contacts OSE Immunotherapeutics Sylvie Détry sylvie.detry@ose-immuno.com Nicolas Poirier Chief Executive Officer nicolas.poirier@ose-immuno.com French Media: FP2COM Florence Portejoie fportejoie@fp2com.fr +33 6 07 768 283 U.S. Media Contact RooneyPartners LLC Kate Barrette kbarrette@rooneypartners.com +1 212 223 0561 Forward-looking statements This press release contains express or implied information and statements that might be deemed forward-looking information and statements in respect of OSE Immunotherapeutics. They do not constitute historical facts. These information and statements include financial projections that are based upon certain assumptions and assessments made by OSE Immunotherapeutics’ management in light of its experience and its perception of historical trends, current economic and industry conditions, expected future developments and other factors they believe to be appropriate. These forward-looking statements include statements typically using conditional and containing verbs such as “expect”, “anticipate”, “believe”, “target”, “plan”, or “estimate”, their declensions and conjugations and words of similar import. Although the OSE Immunotherapeutics management believes that the forward-looking statements and information are reasonable, the OSE Immunotherapeutics’ shareholders and other investors are cautioned that the completion of such expectations is by nature subject to various risks, known or not, and uncertainties which are difficult to predict and generally beyond the control of OSE Immunotherapeutics. These risks could cause actual results and developments to differ materially from those expressed in or implied or projected by the forward-looking statements. These risks include those discussed or identified in the public filings made by OSE Immunotherapeutics with the AMF. Such forward-looking statements are not guarantees of future performance. This press release includes only summary information and should be read with the OSE Immunotherapeutics Universal Registration Document filed with the AMF on April 30, 2024, including the annual financial report for the fiscal year 2023, available on the OSE Immunotherapeutics’ website. Other than as required by applicable law, OSE Immunotherapeutics issues this press release at the date hereof and does not undertake any obligation to update or revise the forward-looking information or statements. Attachment EN_240701_OSE-127 Blood

OSE Immunotherapeutics Reports on its 2024 General Shareholders’ Meeting and the Evolution of the Board of Directors Ready to Drive the Strategic Company’s Growth Nantes, France – June 19, 2024, 6:15pm CET – OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) today announced that all the resolutions submitted to a vote at the Combined General Shareholders’ Meeting were approved as proposed by OSE Immunotherapeutics’ Board of Directors. Shareholders also approved appointment of four new independent Directors: Marc Dechamps, Martine George, Markus Goebel and Cécile Nguyen-Cluzel who together bring a wealth of experience from leadership roles in the biopharmaceutical and health financial industry reenforcing the key strategic skills of the Board. The newly installed Board has appointed Didier Hoch as its Chairman. He succeeds Dominique Costantini who did not run for a new mandate at this Shareholders’ meeting. Didier Hoch, of OSE Immunotherapeutics’ Chairman of the Board, comments: “I am very honoured by the confidence the Board of Directors has placed in me by appointing me as OSE Chairman of the Board. I would like to thank Dominique Costantini for her support and active collaboration throughout the past years. I am very pleased to welcome new international board members, highly experienced pharmaceutical and financial experts who bring strong track record in scientific and medical innovation, business strategy and international scope. Alongside the OSE Management team and Nicolas Poirier, the CEO, they will contribute to further Company’s development and growth strategy.” Dominique Costantini adds:” I am very proud since the founding of OSE to have contributed to its evolution and its current positioning on attractive therapeutic innovations, through the exceptional work carried out by the entire OSE team. I am very pleased with the appointment of Didier Hoch as OSE Chairman and by the support of such a highly qualified Board. Didier’s deep knowledge and understanding of the Company and his rich international experience in the pharmaceutical industry fit perfectly with the OSE growth strategy. I am fully confident in the management team, which will be strengthened as part of a succession plan, we have implemented to ensure the continuity of my operational functions.” The results of each resolution voted on can be found on the Company’s website in the “Investor – General Shareholders’ Meeting” section: https://ose-immuno.com/en/general-shareholders-meetings/ In total, the shareholders who participated in person, by proxy to the chairwoman, by proxy to a third party or by postal vote owned 8,054,991 shares representing 12,131,115 votes, i.e. 37% of the share capital and 44.4% of the voting rights. The shareholders approved the annual and consolidated financial statements as of December 31, 2023. The Board of Directors of OSE Immunotherapeutics now includes the 10 following members: Didier Hoch, ChairmanMaryvonne Hiance, Vice-ChairwomanAnne-Laure Autret-Cornet, Director representing the employee shareholders and Chief Financial OfficerMarc Dechamps, independent DirectorBrigitte Dréno, independent DirectorMartine George, independent DirectorMarkus Goebel, independent DirectorEric Leire, independent DirectorCécile Nguyen-Cluzel, independent DirectorNicolas Poirier, Director and Chief Executive Officer ABOUT OSE IMMUNOTHERAPEUTICS OSE Immunotherapeutics is a biotech company dedicated to developing first-in-class assets in immuno-oncology (IO) and immuno-inflammation (I&I). The Company’s current well-balanced first-in-class clinical pipeline includes: Tedopi® (immunotherapy activating tumor specific T-cells, off-the-shelf, neoepitope-based): this cancer vaccine is the Company’s most advanced product; positive results from the Phase 3 trial (Atalante 1) in Non-Small Cell Lung Cancer patients in secondary resistance after checkpoint inhibitor failure. Other Phase 2 trials, sponsored by clinical oncology groups, of Tedopi® in combination are ongoing in solid tumors.OSE-279 (anti-PD1): first positive results in the ongoing Phase 1/2 in solid tumors. OSE-127 - lusvertikimab (humanized monoclonal antibody antagonist of IL-7 receptor); ongoing Phase 2 in Ulcerative Colitis (sponsor OSE Immunotherapeutics); ongoing preclinical research in leukemia (OSE Immunotherapeutics).FR-104/VEL-101 (anti-CD28 monoclonal antibody): developed in partnership with Veloxis Pharmaceuticals, Inc. in transplantation; ongoing Phase 1/2 in renal transplant (sponsor Nantes University Hospital); successful Phase 1 in the US (sponsor Veloxis Pharmaceuticals, Inc.).Anti-SIRPα monoclonal antibody developed in partnership with Boehringer Ingelheim in advanced solid tumors and cardiovascular-renal-metabolic diseases (CRM); positive Phase 1 dose escalation results in monotherapy and in combination; Phase 2 in CRM diseases planned to be initiated end of 2024.ABBV-230 (ChemR23 agonist mAb) developed in partnership with AbbVie in chronic inflammation. OSE Immunotherapeutics expects to generate further significant value from its three proprietary drug discovery platforms, which are central to its ambitious goal to deliver next-generation first-in-class immunotherapies: Pro-resolutive mAb platform focused on targeting and advancing inflammation resolution and optimizing the therapeutic potential of targeting Neutrophils and Macrophages in I&I. ABBV-230 (licensed to AbbVie) is the first candidate generated by the platform, additional discovery programs ongoing on new pro-resolutive GPCRs.Myeloid Checkpoint platform focused on optimizing the therapeutic potential of myeloid cells in IO by targeting immune regulatory receptors expressed by Macrophages and Dendritic cells. BI 765063 and BI 770371 (licensed to Boehringer Ingelheim) are the most advanced candidates generated by the platform. Ongoing additional discovery programs, in particular with positive preclinical results obtained in monotherapy with new anti-CLEC-1 mAbs. BiCKI® Platform is a bifunctional fusion protein platform built on the key backbone component of anti-PD1 combined with a new immunotherapy target to increase anti-tumor efficacy. A first program has been acquired by Boehringer Ingelheim. Additional information about OSE Immunotherapeutics assets is available on the Company’s website: www.ose-immuno.com. Follow us on X and LinkedIn. Contacts Sylvie Détrysylvie.detry@ose-immuno.comNicolas PoirierChief Executive Officer nicolas.poirier@ose-immuno.comFrench Media: FP2COMFlorence Portejoiefportejoie@fp2com.fr+33 6 07 768 283U.S. Media ContactRooneyPartners LLCKate Barrettekbarrette@rooneypartners.com+1 212 223 0561 Forward-looking statements This press release contains express or implied information and statements that might be deemed forward-looking information and statements in respect of OSE Immunotherapeutics. They do not constitute historical facts. These information and statements include financial projections that are based upon certain assumptions and assessments made by OSE Immunotherapeutics’ management in light of its experience and its perception of historical trends, current economic and industry conditions, expected future developments and other factors they believe to be appropriate. These forward-looking statements include statements typically using conditional and containing verbs such as “expect”, “anticipate”, “believe”, “target”, “plan”, or “estimate”, their declensions and conjugations and words of similar import. Although the OSE Immunotherapeutics management believes that the forward-looking statements and information are reasonable, the OSE Immunotherapeutics’ shareholders and other investors are cautioned that the completion of such expectations is by nature subject to various risks, known or not, and uncertainties which are difficult to predict and generally beyond the control of OSE Immunotherapeutics. These risks could cause actual results and developments to differ materially from those expressed in or implied or projected by the forward-looking statements. These risks include those discussed or identified in the public filings made by OSE Immunotherapeutics with the AMF. Such forward-looking statements are not guarantees of future performance. This press release includes only summary information and should be read with the OSE Immunotherapeutics Universal Registration Document filed with the AMF on April 30, 2024, including the annual financial report for the fiscal year 2023, available on the OSE Immunotherapeutics’ website. Other than as required by applicable law, OSE Immunotherapeutics issues this press release at the date hereof and does not undertake any obligation to update or revise the forward-looking information or statements. té Nantes, France – le 19 juin 2024, 18 heures 15 – OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) annonce que l’Assemblée générale réunie ce jour a approuvé toutes les résolutions proposées par le Conseil d’administration. Les actionnaires ont également approuvé la nomination de quatre nouveaux administrateurs indépendants : Marc Dechamps, Martine George, Markus Goebel et Cécile Nguyen-Cluzel qui apportent à la Société leur grande expérience du leadership dans l’industrie biopharmaceutique et renforcent les compétences clés du Conseil d’administration. Le nouveau Conseil a nommé Didier Hoch en tant que Président du Conseil. Il succède à Dominique Costantini qui n’a pas souhaité renouveler son mandat d’administrateur lors de cette Assemblée générale des actionnaires. Didier Hoch, Président du Conseil d’administration d’OSE Immunotherapeutics, commente : « Je suis très honoré de la confiance que me témoigne le Conseil en me nommant Président d’OSE. Je voudrais remercier Dominique Costantini pour son soutien et pour sa collaboration active tout au long de ces dernières années. Je suis très heureux d’accueillir des nouveaux administrateurs internationaux très expérimentés dans les domaines de l’industrie pharmaceutique et de la finance. Ils nous apportent leur expérience de la science, de l’innovation médicale et de la stratégie d’entreprise. Aux côtés de l’équipe de direction d’OSE et de Nicolas Poirier, son Directeur général, ils vont contribuer au développement et à la stratégie de croissance de la Société ». Dominique Costantini ajoute : « Je suis très honorée d’avoir contribué à l’évolution d’OSE depuis sa création et à son positionnement actuel sur des innovations thérapeutiques de premier plan grâce au travail exceptionnel de toute l’équipe d’OSE. Je suis très heureuse de la nomination de Didier Hoch en tant que Président d’OSE et du soutien d’un Conseil hautement qualifié. Son excellente connaissance de la Société et de ses enjeux et son expérience internationale dans l’industrie pharmaceutique sont en parfaite adéquation avec la stratégie de croissance d’OSE. J’ai toute confiance dans l’équipe de direction qui sera renforcée dans le cadre d’un plan de succession que nous avons mis en place pour assurer la continuité de mes fonctions opérationnelles ». Le résultat complet des votes de l’Assemblée générale mixte est disponible sur le site internet de la Société, rubrique Investisseurs/Assemblée Générale : https://www.ose-immuno.com/assemblees-generales/ Au total, les actionnaires ayant participé en présentiel, par pouvoir au président, pouvoir à un tiers ou vote par correspondance possédaient 8 054 991 actions représentant 12 131 115 voix, soit 37 % du capital et 44,4 % des droits de vote. L’Assemblée générale mixte a adopté toutes les résolutions proposées par le Conseil d’administration. Les actionnaires ont approuvé les comptes sociaux et les comptes consolidés de l’exercice clos le 31 décembre 2023. Le Conseil d’administration d’OSE Immunotherapeutics comprend 10 administrateurs : Didier Hoch, PrésidentMaryvonne Hiance, Vice-PrésidenteAnne-Laure Autret-Cornet, Administratrice représentant les salariés actionnaires et Directrice financièreMarc Dechamps, administrateur indépendantBrigitte Dréno, administratrice indépendanteMartine George, administratrice indépendanteMarkus Goebel, administrateur indépendantEric Leire, administrateur indépendantCécile Nguyen-Cluzel, administratrice indépendanteNicolas Poirier, administrateur et Directeur général À PROPOS D’OSE IMMUNOTHERAPEUTICS OSE Immunotherapeutics est une société de biotechnologie qui développe des produits first-in-class en immuno-oncologie (IO) et immuno-inflammation (I&I). Son portefeuille clinique first-in-class comprend : Tedopi® (immunothérapie d’activation des lymphocytes T spécifiques contre les cellules cancéreuses, « off-the-shelf » à base de néo-épitopes) : le produit le plus avancé de la Société ; résultats positifs de l’essai de Phase 3 (Atalante 1) dans le cancer du poumon non à petites cellules (CPNPC) chez les patients en résistance secondaire après échec d’un inhibiteur de point de contrôle. D’autres essais, promus par des groupes cliniques en oncologie, de Tedopi® en combinaison sont en cours dans des tumeurs solides.OSE-279 (anti-PD1) : Premiers résultats positifs de l’étude de Phase 1/2 en cours dans les tumeurs solides.OSE-127 - Lusvertikimab (anticorps monoclonal humanisé antagoniste du récepteur IL-7) : Phase 2 en cours dans la rectocolite hémorragique (promoteur OSE Immunotherapeutics) ; des travaux de recherche préclinique en cours dans les leucémies (OSE Immunotherapeutics). FR104/VEL-101 (anticorps monoclonal anti-CD28) : développé en partenariat avec Veloxis Pharmaceuticals, Inc. dans la transplantation ; Phase 1/2 en cours dans la transplantation rénale (sous la promotion du Centre Hospitalier Universitaire de Nantes) ; Phase 1 finalisée avec succès aux Etats-Unis (promoteur Veloxis Pharmaceuticals, Inc.).Anticorps monoclonaux anti-SIRPα développés en partenariat avec Boehringer Ingelheim (BI) dans les tumeurs solides avancées et les maladies cardiovasculaires, rénales et métaboliques (CVRM) ; résultats positifs de la Phase 1 d’escalade de dose en monothérapie et en association ; démarrage d’une Phase 2 dans les maladies CVRM prévu fin 2024.ABBV-230 (anticorps monoclonal agoniste de ChemR23) développé en partenariat avec AbbVie dans l’inflammation chronique. OSE Immunotherapeutics vise à créer une valeur significative à travers ses trois plateformes de recherche brevetées, au centre de son objectif de délivrer des traitements d’immunothérapie de nouvelle génération first-in-class : Plateforme Anticorps monoclonaux pro-résolutifs qui vise à améliorer la résolution de l’inflammation et à optimiser le potentiel thérapeutique du ciblage des neutrophiles et des macrophages en I&I. ABBV-230 (licencié à AbbVie) est le premier candidat issu de cette plateforme, d’autres programmes de recherche sont en cours sur des nouvelles cibles GPCRs.Plateforme Points de contrôle myéloïdes qui vise à optimiser le potentiel thérapeutique des cellules myéloïdes en IO en ciblant les récepteurs immunitaires régulateurs exprimés par les macrophages et les cellules dendritiques. BI 765063 et BI 770371 (licenciés à Boehringer Ingelheim) sont les candidats les plus avancés générés par cette plateforme. D’autres programmes de recherche sont en cours, en particulier le nouvel anticorps monoclonal anti-CLEC-1 qui a montré des résultats précliniques positifs en monothérapie.Plateforme BiCKI®, une plateforme bifonctionnelle de protéines de fusion construite autour d’une ossature centrale anti-PD1 fusionnée à une nouvelle cible d’immunothérapie pour augmenter l’efficacité antitumorale. Un premier programme a été acquis par Boehringer Ingelheim. Plus d’informations sur les actifs d’OSE Immunotherapeutics sont disponibles sur le site de la Société : http://ose-immuno.comSuivez-nous sur X et Linkedln. Contacts Sylvie Détrysylvie.detry@ose-immuno.comNicolas PoirierChief Executive Officer nicolas.poirier@ose-immuno.comFrench Media: FP2COMFlorence Portejoiefportejoie@fp2com.fr+33 6 07 768 283U.S. Media ContactRooneyPartners LLCKate Barrettekbarrette@rooneypartners.com +1 212 223 0561 Déclarations prospectives Ce communiqué contient de manière implicite ou expresse des informations et déclarations pouvant être considérées comme prospectives concernant OSE Immunotherapeutics. Elles ne constituent pas des faits historiquement avérés. Ces informations et déclarations comprennent des projections financières reposant sur des hypothèses ou suppositions formulées par les dirigeants d’OSE Immunotherapeutics à la lumière de leur expérience et de leur perception des tendances historiques, de la situation économique et sectorielle actuelle, de développements futurs et d’autres facteurs qu’ils jugent opportuns.Ces déclarations prospectives peuvent être souvent identifiées par l’usage du conditionnel et par les verbes « s’attendre à », « anticiper », « croire », « planifier » ou « estimer » et leurs déclinaisons et conjugaisons ainsi que par d’autres termes similaires.Bien que la direction d’OSE Immunotherapeutics estime que ces déclarations prospectives sont raisonnables, les actionnaires d’OSE Immunotherapeutics et les autres investisseurs sont alertés sur le fait que leur réalisation est sujette par nature à de nombreux risques connus ou non et incertitudes, difficilement prévisibles et en dehors du contrôle d’OSE Immunotherapeutics. Ces risques peuvent impliquer que les résultats réels et développements effectivement réalisés diffèrent significativement de ceux indiqués ou induits dans ces déclarations prospectives. Ces risques comprennent notamment ceux développés ou identifiés dans les documents publics déposés par OSE Immunotherapeutics auprès de l’AMF. De telles déclarations prospectives ne constituent en rien la garantie de performances à venir.Ce communiqué n’inclut que des éléments résumés et doit être lu avec le Document d’Enregistrement Universel d’OSE Immunotherapeutics, enregistré par l’AMF le 30 avril 2024, incluant le rapport financier annuel 2023, disponible sur le site internet d’OSE Immunotherapeutics.OSE Immunotherapeutics ne prend aucun engagement de mettre à jour les informations et déclarations prospectives à l’exception de ce qui serait requis par les lois et règlements applicables. Attachment EN_240619_GAM Results

NANTES, France--(BUSINESS WIRE)-- Regulatory News: OSE Immunotherapeutics SA (ISIN: FR0012127173; Mnemo: OSE) updates on its clinical portfolio advancements and provides 2024 outlook. Nicolas Poirier, Chief Executive Officer of OSE Immunotherapeutics, comments: “The Company has a broad portfolio of 5 products in clinical development with significant advances reached in 2023 and key milestones expected in 2024. Our preclinical programs are focused on 3 immunotherapy platforms, a source of innovation in immuno-oncology and inflammatory diseases linked to myeloid cells or T lymphocytes. Part of the portfolio generates revenues from existing industrial agreements and the progress of proprietary products, in clinical and preclinical stages, is a source of potential future revenue in markets with high medical needs. Our shared ambition at OSE is to create value by leading our two advanced assets in phase 2 and phase 3 to a clinical inflection point allowing a structuring agreement. Moreover, we will reinforce the partnership and recurrent revenue strategy by relying on pharmaceutical partners recognized in the relevant markets for our other first-in-class innovative programs. All of which has been put in place over the last 12 months will help advance the Company’s growth path in the coming weeks and months.” Proprietary programs: a broad portfolio of advanced products Tedopi®, optimized epitope-based cancer vaccine Dossier and protocol approved by the FDA (Food and Drug Administration) in mid-January to launch a new confirmatory Phase 3 clinical trial in second-line lung cancer In September 2023, the positive results from the first Phase 3 clinical trial in third-line lung cancer with secondary resistance to immune checkpoint inhibitors (ICI) were published in Annals of Oncology. In March 2023, based on these results, compassionate use programs had been approved in France and Italy as well as an extended access made available in Spain. In July 2023, a patent was granted in the United States for the use of Tedopi® in cancer after failure with ICI. Based on the positive recommendations from the US FDA and from the European Medicines Agency (EMA) in early 2023, the Company filed a dossier to the FDA to continue the development of Tedopi® in the same patient population in secondary resistance, but in second-line treatment (due to changing medical practice and earlier administration of ICI, now used in first-line treatment in combination with chemotherapy). Moreover, a specific dossier was filed to the FDA to validate a companion diagnostic test to identify HLA-A2-positive cancer patients eligible for treatment with Tedopi®. This test, currently under evaluation, has been developed in close collaboration with GenDx (as part of funding from Bpifrance received in June 2023). The full dossier to initiate the new confirmatory Phase 3 trial of Tedopi® was filed to the FDA end of 2023. Both dossiers have just received a positive review from the American Agency that should enable trial initiation in the US in Q2 2024, and extension to Europe in S2 2024. In parallel, three exploratory Phase 2 clinical trials, sponsored by cooperative clinical oncology groups, explored the interest of Tedopi® in combination in several types of solid tumors: Pancreatic cancer: results expected in 2024, in combination with chemotherapy by FOLFIRI (sponsor: GERCOR); Ovarian cancer: results expected in 2025, in combination with an anti-PD1, pembrolizumab (sponsor: ARCAGY-GINECO); in lung cancer: results expected in 2025, in combination with an anti-PDA, nivolumab (sponsor: FoRT). OSE-127/Lusvertikimab: anti-IL-7 Receptor monoclonal antibody Phase 2 clinical trial ongoing in ulcerative colitis; end of patient enrollment expected in Q1 2024 An article published in The Journal of Immunology (February 2023), reported on the positive Phase 1 clinical results with a tolerability pro pharmacodynamic parameters determining the recommended dose in Phase 2. A decreased IL-7 pathway gene signature in human peripheral blood cells has been demonstrated confirming the efficient blockade of the target. In May 2023, OSE retained global and full rights on Lusvertikimab to continue its strategic development in ulcerative colitis. Further to a mutual agreement between both companies, Servier decided not to continue the clinical development of its program after an exploratory negative trial (a phase 2 in a complex and rare systemic disease: the Sjögren syndrome) and a review of its portfolio. The ongoing Phase 2 trial (CoTikiS trial: NCT04882007), a randomized, double-blind versus placebo study, is evaluating the efficacy and safety of Lusvertikimab in patients with moderate to severe active Ulcerative Colitis, naïve of any treatment or who previously failed or lost response or were intolerant to previous treatment(s) including biotherapies and immunosuppressive treatments. In July 2023, based on regular positive reviews, the study’s Drug Monitoring Board recommended continuing the trial until its completion. Another recommendation from the Committee was implemented to strengthen the recruitment planned after the failure of biological treatments (biotherapies of the anti-TNF type or other biological classes), due to patients naive to biotherapies (having not previously received biotherapies). Due to this recommendation, as well as to the geopolitical context, the trial was redirected towards new clinical centers in countries further west in Europe, concerning patients naive to biological treatments, who are much more numerous in the countries from Eastern Europe. Due to this rebalancing, the end of recruitment is now expected in Q1 2024, and the first results (from induction to week 10 and after 6 months of maintenance) are expected in mid-2024. Moreover, in July 2023, the EMA provided a positive opinion on Orphan Drug Designation for Lusvertikimab for the treatment of Acute Lymphoblastic Leukemia (ALL), opening future potential new indications in ALL, rare diseases with limited treatment options. OSE-279: proprietary anti-PD1 Phase 1/2 clinical trial ongoing in solid tumors The first positive clinical results of the trial initiated in December 2022, and announced in October 2023, show several confirmed antitumor responses in patients with solid tumors. An updated presentation of these results is planned for the end of February 2024 (ESMO-TAT conference). Thus, from Q1 2024, the Company could have validated doses and therapeutic regimens to consider the implementation of possible other clinical trials. OSE-279, a potentially “best-in-class” product, represents a strategic opportunity currently being evaluated allowing continued development as a monotherapy in pre-identified niche indications in cancers with high medical need, and/or to explore combinations with other OSE drug candidates or with external active ingredients that could open the way to new potential partnerships. Industrial partnerships programs: important steps achieved OSE-172/BI 765063, selective SIRPα antagonist (that recognizes the V1 variant) and BI 770371 (that recognizes both the V1 and V2 variants), developed in partnership with Boehringer Ingelheim Clinical advancement of SIRPα selective inhibitors in solid tumors BI 765063 is being evaluated by Boehringer Ingelheim in different combinations in patients with metastatic or recurrent head and neck squamous cell carcinoma (HCC) or hepatocellular carcinoma (HCC) in an international study phase 1b initiated in May 2022 and conducted in the United States, Europe and Asia (NCT05249426). Promising results from the first Phase 1a study of early clinical efficacy data and biomarkers predictive of response and survival (on SIRPα, not CD47) were presented at the AACR Annual Meeting (American Association for Cancer Research) in April 2023 BI 770371 is a new selective anti-SIRPα monoclonal antibody (co-owned by OSE and Boehringer Ingelheim) recognizing both the V1 and V2 variants of SIRPα (the V2 allele being more common in Asian countries). It is currently being studied as a monotherapy and in combination with a PD1 inhibitor (BI 754091) in an international phase 1 dose escalation/expansion clinical trial (NCT05327946) conducted in Canada, the United States, and Japan in patients with solid tumors. The first clinical results of BI 770371, showing a manageable safety pro a maximum tolerated dose not reached, were presented at the ESMO (European Society for Medical Oncology) conference in October 2023. FR104/VEL-101: anti-CD28 selective monoclonal antibody, developed in partnership with Veloxis Pharmaceuticals, Inc. Two clinical trials, a phase 1/2 and a phase 1, completed in 2023 – Results expected in 2024 The ongoing phase 1/2 clinical trial, conducted and sponsored by the University Hospital Center of Nantes, evaluates the first use of FR104/VEL-101 intravenously in patients who have received a kidney transplant. After the end of recruitment was announced in July 2023, a positive interim analysis of the study was presented in December 2023 at the annual congress of the Société Francophone de Transplantation, showing the safety of the product used in combination and the first signals of efficacy in these kidney transplant recipients. Another phase 1 clinical trial was conducted and sponsored by Veloxis to evaluate FR104/VEL-101 subcutaneously. This trial was successfully completed in early 2023. Veloxis also obtained a “Fast Track” designation from the FDA for the development of FR104/VEL-101 for prophylaxis against transplant rejection. Following on from these two results, Veloxis plans to continue developing the product subcutaneously in an international phase 2 study in kidney transplantation. ABOUT OSE IMMUNOTHERAPEUTICS OSE Immunotherapeutics is a biotech company dedicated to developing first-in-class assets in immuno-oncology and immuno-inflammation. The Company’s current well-balanced first-in-class clinical pipeline includes: Tedopi® (immunotherapy activating tumor specific T-cells, off-the-shelf, neoepitope-based): this cancer vaccine is the Company’s most advanced product; positive results from the Phase 3 trial (Atalante 1) in Non-Small Cell Lung Cancer patients in secondary resistance after checkpoint inhibitor failure. Other Phase 2 trials, sponsored by clinical oncology groups, of Tedopi® in combination are ongoing in solid tumors. OSE-279 (anti-PD1): first positive results in the ongoing Phase 1/2 in solid tumors. OSE-279 is the backbone therapy of the BiCKI® platform. OSE-127 - lusvertikimab (humanized monoclonal antibody antagonist of IL-7 receptor); ongoing Phase 2 in Ulcerative Colitis (sponsor OSE Immunotherapeutics); ongoing preclinical research in leukemia (OSE Immunotherapeutics). FR-104/VEL-101 (anti-CD28 monoclonal antibody): developed in partnership with Veloxis Pharmaceuticals, Inc. in transplantation; ongoing Phase 1/2 in renal transplant (sponsor Nantes University Hospital); successful Phase 1 in the US (sponsor Veloxis Pharmaceuticals, Inc.). BI 765063 and BI 770371 (anti-SIRPα monoclonal antibody on CD47/SIRPα pathway) developed in partnership with Boehringer Ingelheim in advanced solid tumors; positive Phase 1 dose escalation results in monotherapy and in combination, in particular with anti-PD-1 antibody ezabenlimab; international Phase 1b ongoing clinical trial in combination with ezabenlimab alone or with other drugs in patients with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) and hepatocellular carcinoma (HCC). OSE Immunotherapeutics expects to generate further significant value from its two proprietary drug discovery platforms, which are central to its ambitious goal to deliver next-generation first-in-class immunotherapies: Myeloid checkpoint platform focused on optimizing the therapeutic potential of myeloid cells in immuno-oncology. - CLEC-1 (a C-type lectin receptor) is a myeloid checkpoint and a novel therapeutic target of interest in immuno-oncology. Pro-resolutive antibody platform focused on controlling myeloid cell-mediated inflammation. - OSE-230 (ChemR23 agonist mAb) is the most advanced candidate generated by this platform with the potential to resolve chronic inflammation by driving affected tissues to tissue integrity. Increased cytokine platform focused on delivering the potential of modified cytokine in immuno-oncology or in auto-immune diseases. - The most advanced candidate is BiCKI®-IL-7 targeting anti-PD1xIL-7 in immuno-oncology. Additional information about OSE Immunotherapeutics assets is available on the Company’s website: Click and follow us on Twitter and LinkedIn Forward-looking statements This press release contains express or implied information and statements that might be deemed forward-looking information and statements in respect of OSE Immunotherapeutics. They do not constitute historical facts. These information and statements include financial projections that are based upon certain assumptions and assessments made by OSE Immunotherapeutics’ management in light of its experience and its perception of historical trends, current economic and industry conditions, expected future developments and other factors they believe to be appropriate. These forward-looking statements include statements typically using conditional and containing verbs such as “expect”, “anticipate”, “believe”, “target”, “plan”, or “estimate”, their declensions and conjugations and words of similar import. Although the OSE Immunotherapeutics management believes that the forward-looking statements and information are reasonable, the OSE Immunotherapeutics’ shareholders and other investors are cautioned that the completion of such expectations is by nature subject to various risks, known or not, and uncertainties which are difficult to predict and generally beyond the control of OSE Immunotherapeutics. These risks could cause actual results and developments to differ materially from those expressed in or implied or projected by the forward-looking statements. These risks include those discussed or identified in the public filings made by OSE Immunotherapeutics with the AMF. Such forward-looking statements are not guarantees of future performance. This press release includes only summary information and should be read with the OSE Immunotherapeutics Universal Registration Document filed with the AMF on May 2, 2023, including the annual financial report for the fiscal year 2022, available on the OSE Immunotherapeutics’ website. Other than as required by applicable law, OSE Immunotherapeutics issues this press release at the date hereof and does not undertake any obligation to update or revise the forward-looking information or statements. View source version on businesswire.com: Contacts OSE Immunotherapeutics Sylvie Détry sylvie.detry@ose-immuno.com Nicolas Poirier Chief Executive Officer nicolas.poirier@ose-immuno.com French Media: FP2COM Florence Portejoie fportejoie@fp2com.fr +33 6 07 768 283 U.S. Media Contact RooneyPartners LLC Kate Barrette kbarrette@rooneypartners.com +1 212 223 0561 Source: OSE Immunotherapeutics View this news release online at: