Onxeo

Report Publication Announcement • Sep 8, 2020

Onxeo to Attend Key Investor Conferences and Events in the Second Half of 2020

Paris (France), September 8, 2020 – 7:00 am CEST - Onxeo S.A. (Euronext Paris, NASDAQ Copenhagen: ONXEO), ("Onxeo" or "the Company"), a clinical-stage biotechnology company specializing in the development of innovative drugs targeting tumor DNA Damage response (DDR), in particular against rare or resistant cancers, today announced that its management team will attend the following key investor conferences in the coming months:

• H.C. Wainwright 22nd Annual Global Investment Conference

September 14-16, 2020 (virtual conference)

Onxeo's management team will present the Company on September 15 at 1:00 pm EDT (19:00 Paris time) and meet with international investors at this conference organized by the American investment bank H. C. Wainwright & Co. This presentation will be available in replay for 90 days on this link. For more information and to register, click here

• HealthTech Innovation Days - France Biotech

October 5-6, 2020 in Paris, France (virtual conference)

This event includes conferences and meetings between innovative European companies in the biotechnology, medical technology and digital health sectors, pharmaceutical companies, life science investors as well as experts and opinion leaders in the field of healthcare. For more information and to register, click here

• CIC Market Solutions Forum

November 10, 2020 in Paris, France This event gives the opportunity to French and international investors to interact with executives of listed companies. For more information and to register, click here

• Bryan Garnier & Co. European Healthcare Conference

November 16-17, 2020 in Paris, France This event brings together industry leaders, emerging fast-growth companies, innovative technology creators and members of the investment community. For more information and to register, click here

• Direct Dirigeants event – EasyBourse

November 24, 2020 in Paris, France

Presentation by Judith Greciet, CEO of Onxeo, to individual investors and shareholders, moderated by a fund manager.

* Given the evolving epidemic context, the reader is invited to refer to the organizers' websites for possible updates to the conditions of participation.

About Onxeo

Onxeo (Euronext Paris, NASDAQ Copenhagen: ONXEO) is a clinical-stage biotechnology company developing innovative oncology drugs targeting tumor DNA-binding functions through unique mechanisms of action in the soughtafter field of DNA Damage Response (DDR). The Company is focused on bringing early-stage first-in-class or disruptive compounds from translational research to clinical proof-of-concept, a value-creating inflection point appealing to potential partners.

platON™ is Onxeo's proprietary chemistry platform of oligonucleotides acting as decoy agonists, which generates new innovative compounds and broaden the Company's product pipeline.

AsiDNA™, the first compound from platON™, is a first-in-class, highly differentiated DNA Damage Response (DDR) inhibitor based on a decoy and agonist mechanism acting upstream of multiple DDR pathways. Translational research has highlighted the distinctive properties of AsiDNA™, notably its ability to abrogate tumor resistance to PARP inhibitors regardless of the genetic mutation status. AsiDNA™ has also shown a strong synergy with other tumor DNAdamaging agents such as chemotherapy and PARP inhibitors. The DRIIV-1 (DNA Repair Inhibitor-administered IntraVenously) phase I study has evaluated AsiDNA™ by systemic administration (IV) in advanced solid tumors and confirmed the active doses as well as a favorable human safety profile. The ongoing DRIIV-1b extension study is assessing the safety and efficacy of a 600 mg dose of AsiDNA™ in combination with carboplatin and then with carboplatin and paclitaxel, in patients with solid tumors who are eligible for such treatments. Preliminary results from the first cohort with carboplatin alone showed good tolerability, stabilization of the disease and an increase in the duration of treatment compared to previous treatments.

OX401 is a new drug candidate from platON™, optimized to be a next-generation PARP inhibitor acting on both the DNA Damage Response and the activation of immune response, without inducing resistance. OX401 is undergoing preclinical proof-of-concept studies, alone and in combination with immunotherapies.

For further information, please visit www.onxeo.com.

Forward looking statements

This communication expressly or implicitly contains certain forward-looking statements concerning Onxeo and its business. Such statements involve certain known and unknown risks, uncertainties and other factors, which could cause the actual results, financial condition, performance or achievements of Onxeo to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Onxeo is providing this communication as of this date and does not undertake to update any forward-looking statements contained herein as a result of new information, future events or otherwise. For a discussion of risks and uncertainties which could cause actual results, financial condition, performance or achievements of Onxeo to differ from those contained in the forward-looking statements, please refer to chapter 3 "Risk Factors" ("Facteurs de Risque") of the Company's universal registration document filed with the Autorité des marchés financiers on April 27, 2020 under number D.20-0362, which is available on the websites of the Autorité des marchés financiers(www.amf-france.org) an the Company (www.onxeo.com).

Contacts

Onxeo Valerie Leroy, Investor Relations investors@onxeo.com +33 1 45 58 76 00

Media Relations Nicolas Merigeau NewCap onxeo@newcap.eu +33 1 44 71 94 98

Investor Relations / Strategic Communication Dušan Orešanský / Emmanuel Huynh NewCap onxeo@newcap.eu +33 1 44 71 94 92

Investor Relations US Brian Ritchie LifeSci Advisors britchie@lifesciadvisors.com +1 212 915 2578