Onxeo : Terms of availability of the preparatory documents for the GM

PRESS RELEASE

Extraordinary General Meeting of February 6, 2023:

availability of preparatory documents

Paris (France), January 18, 2023 - 6:00 pm CET - Onxeo S.A. (Euronext Growth Paris: ALONX), hereafter "Onxeo" or the "Company", a clinical stage biotechnology company specializing in the development of innovative drugs targeting tumor DNA damage response (DDR) mechanisms to fight rare or resistant cancers, today announces the availability of the preparatory documents for its Extraordinary General Meeting which will be held on Monday, February 6, 2023 at 2:00 p.m. at the Renaissance Paris Nobel Tour Eiffel Hotel, 55 avenue Raymond Poincaré, 75116 Paris - France.

The shareholders are called upon to deliberate, in particular, on the authorization to be granted to the Board of Directors to proceed with a capital reduction by way of a reduction in the par value of the shares, as well as on a proposed reverse stock split of the shares comprising the Company's share capital. These two potential operations would only represent a purely arithmetical technical adjustment and have no impact on the value of the share portfolio held by a shareholder, nor on the market capitalization of Onxeo.

The notice of meeting was published in the BALO on December 28, 2022 and a corrective notice was published in the BALO on January 16, 2023. These notices, as well as all documents relating to this General Meeting are available on the Company's website, in theGeneral Meetings section.

About Onxeo

Onxeo (Euronext Growth Paris: ALONX) 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-stagefirst-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 highly differentiated, clinical-stagefirst-in-class candidate in the field of DNA damage response (DDR) applied to oncology. Its decoy and agonist mechanism acting upstream of multiple DDR pathways results in distinctive antitumor properties, including the ability to prevent or abrogate tumor resistance to targeted therapies such as PARP inhibitors and strong synergy with tumor DNA-damaging agents such as radio- chemotherapy. AsiDNA is currently being studied in Europe and the US in combination with other treatment modalities in difficult-to-treat solid tumors.

OX425, the second compound from platON, is a novel DDR Decoy Agonist with high antitumor activity. It also mediates multiple immunostimulatory effects by activating the STING pathway. OX425 is currently undergoing IND-enabling preclinical development.

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 risk factors described in the most recent Company's registration document or in any other periodic financial report and in any other press release, which are available free of charge on the websites of the Company Group (www.onxeo.com) and/or the AMF (www.amf-france.org).

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Contacts

Onxeo

Investor Relations

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Media Relations

Arthur Rouillé NewCap [e-mail][phone]

PRESS RELEASE

Investor Relations / Strategic Communication

Dušan Orešanský / Emmanuel Huynh

NewCap

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