Onxeo

Regulatory Filings • Jan 28, 2020

Onxeo to Present Next-Generation PARP inhibitor, OX401, at PARP & DDR Inhibitors Summit 2020

Paris (France), January 28, 2020 – 5:45 pm CET – Onxeo S.A. (Euronext Paris, NASDAQ Copenhagen: ONXEO), ("Onxeo" or "the Company"), a clinical-stage biotechnology company specializing in the development of innovative drugstargeting tumor DNA Damage Response (DDR), in particular against rare or resistant cancers, today announces that the Company's Chief Scientific Officer, Françoise Bono, will present OX401, a next-generation PARP inhibitor (PARPi) of the Company, during an oral presentation at the PARP & DDR Inhibitors Summit 2020 held in Boston, MA on January 29-30, 2020.

"OX401 benefits from our accumulated insight into the unique decoy agonist mechanism already present in our clinical-stage DDR inhibitor AsiDNA™ and we are excited to present this very innovative PARP inhibitor to the world's most recognized stakeholders in DNA Damage Response," said Françoise Bono, Chief Scientific Officer of Onxeo. "We are in the process of building a strong preclinical data set for OX401, which was optimized to be potent on both PARP inhibition and STING response and to bypass resistance as well as homologous recombination deficiency requirements, two of the major hurdles faced by PARP inhibitors today."

OX401 is the second candidate sourced from Onxeo's proprietary platform of decoy agonists, platON™. This new compound was optimized to maintain this unique mechanism of action, while targeting other DNA-binding proteins and other mechanismsinvolved in tumor growth,such asthe immune response. Its properties position OX401 at the crossroads of two of the most active areas in oncology, DNA Damage Response and immunotherapy.

Session: Innovative Approaches to Targeting the DDR

Date: Thursday, January 30, 2019 - 2:30 pm EST Location: Revere Hotel Boston Common, Boston, MA - USA

Oral presentation: Introducing OX401, a Next Generation PARP Inhibitor Able to Exploit Metabolic Vulnerabilities of Cancer Cells and Inducing a Potent STING Response

• Introducing a 'first-in-class' Decoy Agonist candidate which sequesters and hyperactivates PARP
• Displaying selective activity in tumor cells versus healthy cells, regardless of HR status as OX401 does not induce DNA breaks or acquired resistance
• Exploiting a potentially synthetic lethal pathway in tumors with metabolic vulnerabilities by hyperactivating PARP and inducing NAD+ overconsumption
• Eliciting a potent STING response by inducing micronuclei induction

Access presentation

In addition, Onxeo will also give an update on its lead compound AsiDNA™ in poster sessions on Wednesday, January 29 at 3.15 pm and Thursday, January 30 at 10.50 am (EST).

Access poster

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 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 have shown good tolerance, stabilized disease and increased durations of treatment vs. previous treatment lines.

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.

Onxeo's portfolio also includes belinostat, an HDAC inhibitor (epigenetics). Belinostat is already conditionally FDAapproved 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 more 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 25, 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	Media Relations	Investor Relations / Strategic Communication
Valerie Leroy, Investor Relations	Nicolas Merigeau NewCap	Dušan Orešanský / Emmanuel Huynh NewCap
investors@onxeo.com	onxeo@newcap.eu	onxeo@newcap.eu
+33 1 45 58 76 00	+33 1 44 71 94 98	+33 1 44 71 94 92
		Investor Relations US Brian Ritchie
		LifeSci Advisors
		britchie@lifesciadvisors.com
		+1 212 915 2578