Onxeo

Regulatory Filings • Sep 11, 2019

Onxeo to Attend Key Investor and Scientific Conferences

Paris (France), September 11, 2019 – 5.45 pm CEST - Onxeo S.A. (Euronext Paris, NASDAQ Copenhagen: ONXEO - FR0010095596), ("Onxeo" or "the Company"), a clinical-stage biotechnology company specializing in the development of innovative drugs targeting tumor DNA Damage response (DDR) in oncology, in particular against rare or resistant cancers, today announced that its management team will attend the following key investor and scientific conferences in the coming months:

Investir Day

October 15, 2019, Paris, France

A new event providing shareholders and retail investors with the opportunity to meet and discuss with executives of listed companies. A masterclass session by Judith Greciet, CEO of Onxeo, is scheduled during the event.

The Galien Medstartup 2019

October 24, 2019, in New York, NYC, United-States

The Galien Foundation fosters, recognizes and rewards excellence in scientific innovation to improve the state of human health. Its vision is to be the catalyst for the development of the next generation of innovative treatment and technologies that will impact human health and save lives.

AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics

October 26-30, 2019, in Boston, MA, United-States

The premier international meeting featuring novel cancer therapeutics organized by the American Association for Cancer Research (AACR), the National Cancer Institute (NCI) and the European Organisation for Research and Treatment of Cancer (EORTC).

Direct Dirigeants event with Les Echos – Investir

November 6, 2019, in Paris, France Presentation by Judith Greciet, CEO of Onxeo, to individual investors and shareholders.

2 nd Annual DNA Damage Response Therapeutics Summit

January 29-31, 2019, in Boston, MA, United-States

The Summit brings together the leading pharma and biotech companies accelerating the development of DNA repair pathway inhibitors, to optimize drug discovery, broaden patient population and generate greater efficacy.

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 sought-after 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 DNA-damaging 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 carboplatin and paclitaxel, in patients with solid tumors who are eligible for such 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. In vivo preclinical proof-of-concept data are expected early Q4 2019.

Onxeo's portfolio also includes belinostat, an HDAC inhibitor (epigenetics). Belinostat is already conditionally FDA-approved in the US as a 2nd line treatment for patients with peripheral T cell lymphoma and marketed in the US under the name Beleodaq® (belinostat IV form).

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 the section 5.7.1.4 "Risk Factors" ("Facteurs de Risque") of the 2018 registration document filed with the Autorité des marchés financiers on April 5, 2019 under number D.19- 0282, which is available on the Autorité des marchés financiers website (www.amf-france.org) or on the Company's website (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