17CHU Nantes, Service d’Anatomie et Cytologie Pathologiques, Nantes, France. OSE-127 (monoclonal antibody targeting the CD127 receptor, the alpha chain of the interleukin-7 receptor) is partnered with Servier under an option agreement up to the completion of a Phase 2 clinical trial planned in autoimmune bowel diseases; in parallel, Servier plans a development in the Sjögren syndrome. OSE-127 is being developed in partnership with Servier under an option agreement up to the completion of a Phase 2 clinical trial planned in autoimmune bowel diseases and in parallel, Servier plans a development in Sjögren’s syndrome. Forward-looking statementsThis press release contains express or implied information and statements that might be deemed forward-looking information and statements in respect of OSE Immunotherapeutics. OSE-127 is currently under Phase 1 clinical trial. In preclinical humanized models reconstituted with human T lymphocytes, OSE-127 significantly blocked pathological homing of human T lymphocytes to the inflamed colon thereby preventing destruction of gut mucosa by the T lymphocytes. 12CHU Nantes, Laboratoire d’Immunologie, Center for Immuno Monitoring Nantes-Atlantique (CIMNA), Nantes, France. 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. Interleukin-7 (IL7) is a cytokine that controls the proliferation, apoptosis and activation of CD4 and CD8 effector T-cells in humans. OSE-127, a humanized monoclonal antibody, is an antagonist of the IL7 receptor (IL7R) present on T effector cells, the CD127 receptor, thus down regulating the immune activity. This first notice of allowance in the U.S. is a major step in strengthening the product’s protection and should facilitate the grant of additional patents in other major territories covered by the same patent family. OSE-127 is under an option license agreement signed with Servier in December 2016 to be developed up to the completion of a phase 2 clinical trial planned in ulcerative colitis, an autoimmune bowel disease; in parallel, OSE-127 will be developed in Sjögren’s syndrome, the second most frequent auto-immune disease. The product is currently  in  a Phase 1 trial evaluating the safety and tolerability of single- and multiple-ascending intravenous and subcutaneous doses of OSE-127 in 63 healthy volunteers. NANTES, France, May 20, 2019 (GLOBE NEWSWIRE) -- OSE Immunotherapeutics (ISIN: FR0012127173; Mnémo: OSE) today announces that it has received the first notice of allowance of a patent from the United States Patent and Trademark Office (USPTO) strengthening the protection covering anti-interleukin-7 receptor (IL-7R) antagonist OSE-127, a humanized monoclonal antibody targeting the CD127 receptor, the alpha chain of the IL-7R, that has been shown to induce a powerful antagonistic effect on effector T lymphocytes responsible for causing autoimmune pathologies. Jean-Paul Soulillou, Dr. Sophie Brouard; Bpifrance; The London School of Medicine and Dentistry: Pr. Secondary endpoints included measures of pharmacokinetics, pharmacodynamics and immunogenicity to help assess and understand how the drug is absorbed and metabolized. This press release includes only summary information and should be read with the OSE Immunotherapeutics Reference Document filed with the AMF on 26 April 2019, including the annual financial report for the fiscal year 2018, available on the OSE Immunotherapeutics’ website. 2Centre de Recherche en Transplantation et Immunologie (CRTI), UMR 1064, Inserm, Université de Nantes, Nantes, France. OSE-127 significantly reduced production of gamma interferon expressed by proinflammatory mucosal T lymphocytes. BI 765063 (OSE-172) (anti-SIRPa monoclonal antibody) is under a license and collaboration agreement with Boehringer Ingelheim ; this checkpoint inhibitor has received CTA from French and Belgian health authorities for a Phase 1 clinical trial in multiple cancer indications.

3Institut de Transplantation Urologie Néphrologie (ITUN), Centre Hospitalier Universitaire de Nantes (CHU Nantes), Nantes, France. Click and follow us on Twitter and Linkedln, https://twitter.com/OSEIMMUNOhttps://www.linkedin.com/company/10929673. BiCKI® is a bispecific fusion protein platform built on the key backbone component anti-PD-1 (OSE-279) and targeting innovative targets. OSE-127 is being developed in partnership with Servier* under an option agreement up to the completion of a Phase 2 clinical trial planned in autoimmune bowel diseases and in parallel, Servier plans a development in Sjögren’s syndrome. The product is currently under a Phase 1 clinical trial in which the first healthy volunteers were enrolled and dosed in December 2018. Such forward-looking statements are not guarantees of future performance. This Phase 1 study aimed to evaluate the safety and tolerability of single- and multiple-ascending intravenous and subcutaneous doses of OSE-127 in 63 healthy volunteers. ABOUT OSE-127OSE-127 is a monoclonal immunomodulatory antibody targeting the CD127 receptor, the alpha chain of the interleukin-7 receptor (IL-7R) that induces a powerful antagonist effect on effector T lymphocytes. These risks could cause actual results and developments to differ materially from those expressed in or implied or projected by the forward-looking statements. The blockage of IL-7R prevents the migration of pathogenic T lymphocytes while preserving regulator T lymphocytes ) which have a positive impact in autoimmune diseases. Such forward-looking statements are not guarantees of future performance.

Thomas T. MacDonald; The Institute of Digestive Diseases (IMAD), Nantes;  Icahn School of Medicine at Mount Sinai, New York: Pr. OSE Immunotherapeutics Sylvie Détry Sylvie.detry@ose-immuno.com +33 153 198 757 French Media: FP2COM Florence Portejoie fportejoie@fp2com.fr +33 607 768 283 The Phase 1 study results show a good safety and tolerability profile for OSE-127. 15Université de Tunis El Manar, Laboratoire de génétique, immunologie et pathologies humaines, Faculté des sciences de Tunis, Tunis, Tunisia. 16Hepato-Gastroenterology Department, Claude Huriez Hospital, University of Lille 2, Lille, France. Si vous continuez à utiliser ce site, nous supposerons que vous en êtes satisfait. 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. The company has a diversified first-in-class clinical portfolio consisting of several scientific and technological platforms including neoepitopes and agonist or antagonist monoclonal antibodies, all ideally positioned to fight cancer and autoimmune diseases. “We are very pleased with this first U.S. notice of allowance for a patent application that strengthens OSE-127 intellectual property and further validates the product’s novel and differentiated mechanism of action as an IL-7R full-antagonist. In addition, exploratory biomarkers will be used to assess OSE-127’s potential for the treatment of inflammatory autoimmune diseases. 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. The most advanced therapeutic-candidate, Tedopi®, is a proprietary combination of 10 neo-epitopes aimed at stimulating T-lymphocytes and is currently in Phase 3 development in non-small cell lung cancer (NSCLC) after checkpoint inhibitor failure (anti PD-1 and anti PD-L1) and in Phase 2 testing in pancreatic cancer in combination with checkpoint inhibitor Opdivo®.