UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the Month of May 2023

Commission File Number: 001-38281

ERYTECH Pharma S.A.

(Translation of registrant’s name into English)

60 Avenue Rockefeller

69008 Lyon France

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

☒  Form 20-F             ☐  Form 40-F

INCORPORATION BY REFERENCE

This Report on Form 6-K and Exhibits 99.1 and 99.2 to this Report on Form 6-K shall be deemed to be incorporated by reference into the registration statements on Form F-3 (File Nos. 333-248953 and 333-259690) and registration statements on Form S-8 (File Nos. 333-222673, 333-232670, 333-239429, 333-255900 and 333-265927), of ERYTECH Pharma S.A. (the “Company”) (including any prospectuses forming a part of such registration statements) and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

INFORMATION CONTAINED IN THIS REPORT ON FORM 6-K

On May 23, 2023, ERYTECH Pharma S.A. filed a document d’exemption (the “exemption document”) with the Autorité des marchés financiers (AMF) in France in connection with its previously announced business combination with PHERECYDES Pharma S.A. (“PHERECYDES”). An English translation version of the exemption document is attached as Exhibit 99.1 to this Report on Form 6-K and incorporated herein by reference.

The exemption document incorporates by reference, among others, PHERECYDES’ 2022 annual financial report published on April 27, 2023 (the “PHERECYDES 2022 Annual Financial Report”), including report of the Board of Directors of PHERECYDES on corporate governance included therein. An English translation version of the PHERECYDES 2022 Annual Financial Report is attached as Exhibit 99.2 to this Report on Form 6-K and incorporated herein by reference.

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Exhibit 99.1

MERGER-ABSORPTION OF

BY

EXEMPTION DOCUMENT PREPARED IN CONNECTION WITH THE MERGER BY ABSORPTION OF PHERECYDES PHARMA BY ERYTECH PHARMA

This exemption document (the “Exemption Document”) is available free of charge at the registered office of Erytech Pharma (60 Avenue Rockefeller, 69008 Lyon, France) and on its website (http://www.erytech.com/).

The Exemption Document is also available in electronic format on the AMF’s website (https://www.amf-france.org/).

The Exemption Document incorporates by reference:

In accordance with point 1.5 of Annex I of the Delegated Regulation n°2021-528, it is stated that:

1

Definitions:

In this Exemption Document, and unless otherwise indicated:

2

TABLE OF CONTENTS

3

4

5

6

Mr. Gil Beyen, Chief Executive Officer of Erytech

Persons responsible for the financial information:

Mr. Gil Beyen, Chief Executive Officer and Mr. Eric Soyer, Deputy Chief Executive Officer, Chief Financial Officer and Chief Operating Officer

Phone number: +33 4 78 74 44 38

Fax: +33 4 78 75 56 29

e-mail: investors@erytech.com

Mr. Thibaut du Fayet, Chief Executive Officer of Pherecydes

e-mail : investors@pherecydes-pharma.com

“I certify that the information contained in the Exemption Document relating to Erytech Pharma is, to the best of my knowledge, in accordance with the facts and contains no omission likely to affect its import.”

Mr. Gil Beyen

Chief Executive Officer

“I certify that the information contained in the Exemption Document relating to Pherecydes Pharma is, to the best of my knowledge, in accordance with the facts and contains no omission likely to affect its import.”

Mr. Thibaut du Fayet

Chief Executive Officer

Ruling on the joint request of Erytech and Pherecydes, the President of the Commercial Court of Lyon has, by order of February 28, 2023, appointed Finexsi as merger auditor (commissaire à la fusion), a French public limited liability company (société anonyme) whose registered office is located at 14 rue de Bassano, 75116 Paris, France, represented by Mr. Christophe Lambert, whose mission, in accordance

7

with Article L. 236-10 of the French Commercial Code (Code de commerce), is to (i) verify that the relative values attributed to the shares of the companies participating in the Merger are relevant and that the exchange ratio is fair and (ii) to prepare a report that will be made available to the shareholders of Erytech and Pherecydes (the “Merger Auditor”).

The reports of the Merger Auditor dated May 15, 2023 are attached as ANNEX 2 of the Exemption Document, and are made available to the shareholders of Erytech and Pherecydes.

The reports of the Merger Auditor have also been filed with the registry of the Commercial Courts of Lyon and Nantes in accordance with the regulations in force.

The Exemption Document contains information relating to the companies’ activities and the markets in which they operate. This information is derived from studies carried out either by internal or external sources (e.g. industry publications, specialized studies, information published by market research companies, analysts’ reports). Other information contained in the Exemption Document is publicly available information. The companies believe that this information provides an accurate picture of their reference markets and their competitive position in these markets.

To the best of the companies’ knowledge, such information has been accurately reproduced and no facts have been omitted that would make it inaccurate or misleading. However, this information has not been verified by an independent expert and the companies cannot guarantee that a third party using different methods to collect, analyze or calculate market data would obtain the same results.

ERYTECH Pharma is a public limited liability company incorporated under the laws of France on October 26, 2004, having its registered office at 60, avenue Rockefeller, 69008 Lyon and registered with the Lyon Trade and Companies Register under number 479 560 013.

Legal Entity Identifier (LEI): 969500U8ZZCODU8A9374

Website: http://www.erytech.com/ - The contents of this website are not part of the Exemption Document, unless expressly incorporated by reference.

Phone number: + 33 4 78 74 44 38

Statutory Auditors

8

KPMG S.A., public limited liability, Nanterre Trade and Companies Register 775 726 417, 2 Avenue Gambetta Tour Eqho, Paris la Défense 92066 Nanterre Cedex.

Date of first appointment: June 24, 2016.

Expiry date of the mandate: General Meeting of shareholders approving the financial statements of the financial year ending December 31, 2027.

KPMG Audit Rhône Alpes Auvergne has been the statutory auditor since June 11, 2010 and until its replacement by KPMG S.A. on June 24, 2016 at the end of its mandate.

RSM Paris S.A.S., a simplified joint stock company, Paris Trade and Companies Register 792 111 783, 26, rue Cambacérès, 75008 Paris.

Date of first appointment: June 21, 2019.

Expiry date of the mandate: General Meeting of shareholders approving the financial statements of the financial year ending December 31, 2025.

RSM Rhône Alpes has been the statutory auditor since June 17, 2014 and until its replacement by RSM Paris on June 21, 2019.

Erytech is a clinical-stage biotechnology company, founded in 2004, which develops innovative therapies, resulting from the internal conduct of research and development programs, to cure patients suffering from diseases in therapeutic areas whose needs are not currently met and which are based in particular on red blood cells.

The principal activities of Erytech are presented in Sections 1.1 “Présentation Générale”, 1.2 “Stratégie du Groupe”, 1.3 “Plateformes technologiques”, 1.4 “Tableau des produits en développement”, 1.5 “Eryaspase, une approche unique du traitement en oncologie” and 1.6 “Autres programmes thérapeutiques potentiels de la société” of the Erytech 2022 Universal Registration Document.

9

The table below set forth Erytech’s products candidates pipeline that will evolve following the final completion of the Merger:

Any significant changes affecting Erytech’s operations and principal activities that have occurred since December 31, 2022 are described in Section 1.1 “Présentation Générale” of the Erytech 2022 Universal Registration Document.

Erytech’s principal markets are described in Section 1.8 “Commercialisation” of the Erytech 2022 Universal Registration Document.

None.

The administrative and management bodies of Erytech are described in Section 3.1.1.2 “Organes d’administration et de direction” of the Erytech 2022 Universal Registration Document.

10

As of the date of the Exemption Document, the composition of the board of directors of Erytech is as follows:

11

The identity of the major shareholders of Erytech is presented in Section 4.1 “Répartition du capital et des droits de vote” of the Erytech 2022 Universal Registration Document.

Since the publication of the Erytech 2022 Universal Registration Document, the Company has received the following threshold crossing declaration: “On April 14, 2023, Akkadian Partners (18 rue Robert Stümper, L-2557 Luxembourg), acting on behalf of the fund Akkadian Partners Fund, of which it ensures the management, declared that on April 13, 2023, it had exceeded the threshold of 5% of the Company’s share capital and that it held, on behalf of the said fund, 1,570,000 shares in the Company representing the same number of voting rights, i.e. 5.06% of the share capital and 4.83% of the voting rights.”

12

As of the date of the Exemption Document, the distribution of the share capital is as follows:

Elaia Partners, Go Capital and the pool of shareholders of Pherecydes represented by Mr. Guy Rigaud have declared that they intend, together with AURIGA Partners, to act in concert with respect to Erytech. To the best of the Company’s knowledge, there are no other actions in concert nor shareholder agreement.

The number of employees of Erytech is set forth in Section 1.13.1.1 “Personnel” of the Erytech 2022 Universal Registration Document.

As of the date of the Exemption Document, Erytech has 38 employees.

13

The financial statements of Erytech as at December 31, 2022 and the corresponding auditors’ report are presented in Sections 5.3.3 “Comptes sociaux établis (normes françaises) pour l’exercice clos le 31 décembre 2022” and 5.3.4 “Rapport des commissaires aux comptes sur les comptes sociaux établis pour l’exercice clos le 31 décembre 2022” of the Erytech 2022 Universal Registration Document.

The consolidated financial statements as at December 31, 2022 of the Erytech Group and the corresponding auditors’ report are set out in Sections 5.3.1 “Comptes consolidés établis en normes IFRS pour l’exercice clos le 31 décembre 2022” and 5.3.2 “Rapport des commissaires aux comptes sur les comptes consolidés établis en normes IFRS pour l’exercice clos le 31 décembre 2022” of the Erytech 2022 Universal Registration Document.

The financial statements of Erytech presented in the Erytech 2022 Universal Registration Document are prepared in accordance with accounting standards applicable in France.

The consolidated financial statements of the Erytech Group presented in the Erytech 2022 Universal Registration Document are prepared in accordance with the IFRS accounting standards adopted by the European Union.

Any significant changes having an impact on Erytech’s operations and principal activities that have occurred since December 31, 2022 are described:

The management report is incorporated into the Erytech 2022 Universal Registration Document as per the cross-reference table appearing on pages iv and v of the Erytech 2022 Universal Registration Document.

To the best of Erytech’s knowledge, there are no administrative, legal or arbitration proceedings (including any pending or threatened proceedings) that are likely to have or have had, in the 12 months prior to the date of the Exemption Document, a material effect on the financial position or profitability of Erytech.

14

Announcements relating to changes in Erytech’s strategy following the FDA’s feedbacks:

On April 25, 2022, Erytech announced the sale of Erytech’s state-of-the-art commercial-scale cell therapy manufacturing facility in Princeton, New Jersey, for a total consideration of $44.5 million. Catalent proposed to retain the Erytech’s staff at the site, representing approximately 40 people. Erytech announced that it will retain its manufacturing site in Lyon, and its expertise and capabilities in manufacturing process science to continue innovating in cell therapy manufacturing.

Erytech also provided an update on the progress of its clinical programs (including the BLA application in hypersensitive ALL, based on results of NOPHO-sponsored Phase 2 trial and rESPECT, the Phase 1 investigator-sponsored trial in first-line metastatic pancreatic cancer).

The Company received feedback from the FDA on its iPSP, submitted in July 2022. On August 24, 2022, Erytech announced its decision, following the feedback from the U.S. Food and Drug Administration’s (FDA), to no longer seek approval for Graspa^® for the treatment of patients with ALL with hypersensitivity to pegylated asparaginase. Erytech announced that it has appointed a specialized advisor to evaluate strategic options to leverage its ERYCAPS^® platform with complementary assets and/or a broader corporate transaction. Multiple options are under review, and the Company expects to give further updates on these strategic initiatives in the fourth quarter of this year.

On September 12, 2022, during its financial update for the first half of 2022, Erytech confirmed the sale of its U.S. cell therapy manufacturing facility to Catalent.

Erytech also confirmed that it has stopped activities to submit an application for approval of Graspa^® for the treatment of patients with hypersensitive ALL, following recent feedback from the FDA.

Erytech further announced the suspension of enrollment in the TRYbeCA-2 trial, which evaluates eryaspase in combination with gemcitabine and carboplatin chemotherapy, compared to chemotherapy alone, in metastatic TNBC (first and second lines), following the disappointing results of eryaspase in the TRYbeCA-1 trial in second-line pancreatic cancer. The trial’s Steering Committee met in September 2022 to review the results of the 25 evaluable patients. No clinical benefit was demonstrated, which could be attributed to the immature closure of the trial and the small number of patients.

15

On November 21, 2022, Erytech, on the occasion of the publication of its quarterly results, announced the halt of the program Graspa after FDA feedback on envisaged BLA submission in hypersensitive ALL and following inconclusive results from clinical studies, its intention to focus on its most promising preclinical programs. As a result, Erytech has announced that it has undertaken a restructuring of its staff with the implementation of a job preservation plan and has obtained the approval of the labor authorities in September 2022. Combined with the approximately 40 people who transferred to Catalent after the sale of the Company’s manufacturing facility in Princeton, the global team size will be less than 25% compared to the start of the year 2022. Erytech retains its R&D team and its expertise in key functional areas to keep the ability to restart a pipeline of partnered development programs and maintain a fully operational dual listed company.

Announcements relating to the Merger project:

On February 15, 2023, Erytech and Pherecydes announced the strategic combination of their two companies in order to build on complementary expertise and capabilities of both companies to accelerate development of extended phage therapies for antimicrobial resistance, in particular via the phase II PhagoDAIR study conducted by PHERECYDES, as well as other anti-infective fields and therapeutic areas with high unmet medical needs.

The transaction, supported by key shareholders of each of Pherecydes and Erytech will result in former Pherecydes shareholders holding approximately 49% of the combined entityand will extend the combined company cash runway into third quarter of 2024, with a consolidated cash position of approximately 41 million euros as of December 31, 2022, and would enable funding of existing and novel programs through multiple clinical milestones.

On May 9, 2023, Erytech published its first quarter 2023 results. As of March 31, 2023, Erytech had cash and cash equivalents totaling 30.5 million euros (approximately 33.7 million dollars), compared to 38.8 million euros as of December 31, 2022.

In addition, Erytech indicated that on May 1, 2023, Akkadian Partners had informed the Board of directors that it intended to oppose the project of merging with Pherecydes and take de facto control of Erytech with a view to pursue alternative acquisition projects with Erytech’s cash. In that context, the Management and Board of Erytech have reviewed and assessed the ideas of acquisitions projects mentioned by Akkadian, with the assistance of external financial and legal advisers. After due consideration, Erytech determined that these ideas, were not in the best interest of Erytech and its stakeholders, and remote from Erytech’s strategy and identity, with significant uncertainty and risks associated with these projects. Erytech, while confirming its strategic decision to merge with Pherecydes, will oppose any financial predation project which would not be in the best interest of the company and its stakeholders.

16

On May 16, 2023, Ertytech announced that it have entered into the Merger Agreement with Pherecydes on May 15, 2023. In addition, Erytech announced that Erytech’s board of directors approved on May 15, 2023, the contribution by Elaia Partners, Go Capital and a pool of Pherecydes shareholders represented by Mr. Guy Rigaud, of 827,132 Pherecydes shares to Erytech in consideration of 3,101,745 newly issued Erytech shares. The exchange ratio for the Contribution is the same as for the Proposed Merger. Furthermore, Didier Hoch and Go Capital (represented by Mrs Leila Nicolas) have been appointed by the board of directors of Erytech by way of cooptation. Finally, Erytech announced that it intends to file a request with the President of the Commercial Court of Lyon soliciting the appointment of an ad hoc agent (mandataire ad hoc) who will represent absent Erytech shareholders to ensure that the required quorum is satisfied and the shareholders’ general meeting is allowed to validly resolve on all resolutions set forth on the agenda.

Announcements relating to the approval of the transfer of Erytech’s listing to the Nasdaq:

On October 13, 2022, Erytech announced that it received a “Notification Letter” from the Nasdaq dated October 7, 2022, indicating that, based upon a closing bid price of less than $1.00 per share for the Company’s ADS for the prior 30 consecutive business day period, the Company no longer satisfies Nasdaq Listing Rule 5450(a)(1). Erytech benefited from the applicable grace period of 180 days to regain compliance, or until April 5, 2023. In the event the Company does not regain compliance within the 180-day grace period, and it meets all other listing standards and requirements, the Company may be eligible for an additional 180-day grace period. Erytech confirmed that it intended to regain compliance within the applicable compliance period and to evaluate its options to do so. During this time, the Company’s ADSs will continue to be listed and trade on The Nasdaq Global Select Market and the Company’s business and operations are not affected by the receipt of the Notification Letter.

On April 17, 2023, Erytech announced that it received approval from the Nasdaq Stock Market LLC on April 12, 2023 to transfer the listing of its American Depositary Shares from the Nasdaq Global Select Market to the Nasdaq Capital Market. The transfer became effective at the opening of business on April 14, 2023.

In connection with the transfer to the Nasdaq Capital Market, Nasdaq granted the Company an additional 180-day period (or until October 2, 2023) to regain compliance with the requirement set forth in Nasdaq Listing Rule 5450(a)(1) that the bid price of the Company’s ADS meet or exceed $1.00 per ADS for at least ten consecutive business days. If at any time during this additional time period the closing bid price of the Company’s security is at least $1 per share for a minimum of 10 consecutive business days, Nasdaq will provide written confirmation of compliance and this matter will be closed.

17

Pherecydes Pharma is a public limited liability company incorporated under the laws of France on December 12, 2006, having its registered office at 22, boulevard Benoni Goullin, 44200 Nantes, and registered with the Nantes Trade and Companies Register under number 493 252 266.

Legal Entity Identifier (LEI): 894500LYT3UUN58X3I68

Website: http://www.pherecydes-pharma.com/ - The contents of this website are not part of the Exemption Document, unless expressly incorporated by reference.

Phone number: +33 1 84 86 16 13

Statutory Auditor

PricewaterhouseCoopers Audit, a simplified joint stock company, Nanterre Trade and Companies Register 672 006 483, 63 Rue de Villiers, 92200 Neuilly-sur-Seine.

Date of first appointment: December 12, 2006.

Expiry date of the mandate: General Meeting of shareholders approving the financial statements of the financial year ending December 31, 2025.

Alternate statutory auditor :

Mr. Patrice Morot, 63 Rue de Villiers, 92200 Neuilly-sur-Seine.

Date of first appointment: May 28, 2021.

Expiry date of the mandate : General Meeting of shareholders approving the financial statements of the financial year ending December 31, 2025.

Pherecydes is a clinical-stage biotechnology company, created in 2006, which develops innovative treatments, resulting from the internal conduct of research and development programs, to cure patients suffering from diseases in therapeutic areas whose needs are not currently met and which are based in particular on bacteriophages.

18

The principal activities of Pherecydes are presented in Chapter 1 “Activité de la société et évolution des affaires au cours de l’exercice clos le 31 décembre 2022” of the Pherecydes 2022 Annual Financial Report, in particular in Sections 1.1 “Présentation Générale de l’activité de la Société”, 1.2 “Situation de l’activité et analyse de l’évolution des affaires au cours de l’exercice 2022” and 1.4 “Activité en matière de R&D”.

The table set forth below presents Pherecydes’ product candidate pipeline, which will evolve following the completion of the Merger:

Any significant changes having an impact on Pherecydes’ operations and principal activities that have occurred since December 31, 2022 are described:

Pherecydes focuses its activity on the development of treatments against three specific bacterial species identified by the WHO as the bacteria for which new treatments are most urgently needed and which together account for more than two thirds of the incidence of antibiotic-resistant infections, namely

19

According to the U.S. Centers for Disease Control and Prevention (CDC), the three bacterial infections targeted by Pherecydes alone accounted for 3.7 billion dollars in healthcare costs in 2017¹.

In its report on 2020, the ECDC estimates that the health cost is about 1.8 billion euros. According to this report, the most common bacterium in Europe is E. coli (44.2%), followed by S. aureus (20.6%). P. aeruginosa comes in 5^th position with a rate of 5.6%. Applying the above percentages, the health cost in Europe would therefore be 1.3 billion euros for S. aureus, E. coli and P. aeruginosa alone, the bacteria targeted by Pherecydes.

The first bacterium against which Pherecydes develops treatments is the S. aureus bacterium. This bacterium is resistant to methicillin and is recognized as one of the most dangerous pathogens, classified as a serious threat by the CDC and priority 2 out of 3 “high” by the WHO. It is a common bacterium that spreads in healthcare facilities and the general population.

Pherecydes has selected two active phages to treat infections caused by this bacterium in three different clinical indications, namely osteoarticular prosthesis infections (OAI), diabetic foot ulcers (DFU) and infective endocarditis (IE, heart valve infections).

The second bacterium against which Pherecydes is developing treatments is P. aeruginosa, recognized as one of the most dangerous pathogens, classified as a serious threat by the CDC and priority 1 of 3 “critical” by the WHO. P. aeruginosa causes many types of healthcare-associated respiratory infections (nosocomial diseases), including pneumonia, bloodstream infections, and surgical site infections.

20

Pherecydes has selected four phages active on the P. aeruginosa bacterium with a focus on a pulmonary indication: ventilator-associated pneumonia (VAP), and potentially mucovisidosis (CF, Cystic Fibrosis).

Finally, the third bacterium against which Pherecydes is developing treatments is E. coli, also recognized as one of the most dangerous pathogens, also classified as a serious threat by the CDC and priority 1 out of 3 “critical” by the WHO. E. coli is a digestive tract bacterium of the Enterobacteriaceae family, frequently responsible for infections in human health (UTIs, especially complex urinary tract infections) and in animal health. This bacterium is easily transmitted when hygiene measures are insufficiently respected.

Pherecydes has selected four phages active on E. coli bacteria targeting complicated urinary tract infections (CTI).

The impact of these different clinical positions in Europe (5) and the United States is described thereafter.

Pherecydes has not made any material investments since December 31, 2022 that are in progress and/or for which firm commitments have been made.

21

The administrative and management bodies of Pherecydes are described in chapter 1 of the Pherecydes 2022 Corporate Governance Report:

The composition of the administrative and management bodies of Pherecydes have not changed since December 31, 2022.

The identity of the major shareholders of Pherecydes is presented in Section 6.1 of the Pherecydes 2022 Annual Financial Report.

22

Pherecydes holds 25,142 of its own shares as of the date hereof, i.e. 0.32% of its share capital, under a liquidity contract entrusted to Portzamparc. This contract has been temporarily suspended at the end of the trading session on May 5, 2023.

In addition, the shareholders of the Guy Rigaud Pool entered into a voting agreement on December 22, 2017. This voting agreement entails concerted action.

Pherecydes currently employs 29 people (full-time employees).

The financial statements of Pherecydes as at December 31, 2022 (pages 67 et seq.) and the corresponding auditor’s report (pages 91 et seq.) are presented in the appendix to the Pherecydes 2022 Annual Financial Report.

The financial statements of Pherecydes presented in the Pherecydes 2022 Annual Financial Report have been prepared in accordance with accounting standards applicable in France.

Any significant changes in the financial position of Pherecydes since December 31, 2022 are described:

The management report is incorporated into the Pherecydes 2022 Annual Financial Report in the first part of the document (pages 3 et seq.).

23

To the best of Pherecydes’ knowledge, there are no administrative, legal or arbitration proceedings (including any pending or threatened proceedings), that are likely to have or have had, in the 12 months prior to the date of the Exemption Document, a material effect on the financial position or profitability of Pherecydes.

Elements related to the activity

On April 28, 2022, Pherecydes announced that it had received the first international approval of a compassionate treatment with its phages, in Sweden. The Swedish Medical Products Agency (SMPA) has given its approval to treat a case of osteoarticular infection of a prosthetic joint with Pherecydes Pharma’s anti-S. aureus phages.

On May 30, 2022, Pherecydes announced that it had been granted Compassionate Access Authorization (AAC) Early Access Program from the ANSM (Agence Nationale de Sécurité du Médicament et des produits de santé, the French National Agency for the Safety of Medicines and health products) for its anti-Staphylococcus aureus (S. aureus) phages.

The AAC system allows certain categories of sick patients in France with no therapeutic solutions to benefit from drugs yet to be granted marketing approval. The AAC scheme allows Pherecydes Pharma to make its anti-S. aureus phages available to larger populations and thus generate the first revenue in the Company’s history.

On June 15, 2022, Pherecydes announced the enrollment of the first patient in the phase II study PhagoDAIR.

PhagoDAIR is the world’s first phage therapy study conducted in osteoarticular infections on prostheses caused by Staphylococcus aureus (S. aureus). Its protocol has been approved by the French National Agency for the Safety of Medicines and health products (ANSM) in December 2021 and by the French Committee for the Protection of Individuals (CPP) in February 2022.

24

On June 27, 2022, Pherecydes announced that the results of a preclinical study undertaken with its phages have been presented at the Reanimation 2022 conference organized by the SRLF (Société de Réanimation de Langue Française, the French intensive care society) and held in Paris from June 22 to 24, 2022.

The study was carried out within the framework of the Pneumophage project, associating the UMR1100 and the Diffusion Technique Française company, aimed at demonstrating the effectiveness of inhaled phage therapy in treating ventilator-associated infections.

The results obtained also demonstrate the feasibility of delivering large quantities of active phages by nebulization during mechanical ventilation and the rapid control of the infection in situ in a respiratory model close to humans.

On September 12, 2022, Pherecydes Pharma announced the registration of its phagogram as an in vitro diagnostic test (“Phagogram 1.5”) in accordance with Directive 98/79/EC.

The phagogram is an in vitro diagnostic test to verify the sensitivity of patients’ bacterial strains to Pherecydes phages.

On September 15, 2022, Pherecydes announced the setting up of a Medical Advisory Board comprising prominent international scientific and clinical experts in infectious diseases. This Board will support Pherecydes consolidate its clinical development strategy in phage therapy.

On November 29, 2022, Pherecydes announced that it had received a unanimous recommendation from the Data Safety Monitoring Board (DSMB) to continue without modification the phase II clinical study PhagoDAIR in osteoarticular infections of prostheses caused by Staphylococcus aureus (S. aureus).

The DSMB is an independent expert committee responsible for the open-label review of the PhagoDAIR study safety data and will meet twice a year during the study. Following its first meeting, the committee recommended that the study continue without modification.

On April 15, 2023, Pherecydes presented part of its analytical performance plan adapted to its Phagogram 1.5 in vitro diagnostic test to verify the sensibility of patients’ bacterial strains to Pherecydes phages, at the 33rd European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Copenhagen (Denmark).

25

Changes in governance

On May 23, 2022, Pherecydes announced that the Combined General Meeting held on May 19, 2022 approved the change of the company’s management and administration by adopting a Board of Directors and a General Management.

The current members of the Supervisory Board were appointed as the first directors of Pherecydes. Mr. Didier Hoch was appointed Chairman and CEO and Mr. Thibaut du Fayet was appointed Deputy CEO.

On December 15, 2022, following the Combined General Meeting of Pherecydes shareholders, the Board of Directors adopted the following decisions: the functions of Chief Executive Officer and Chairman of the Board of Directors were separated, Mr. Thibaut du Fayet, previously Deputy Chief Operating Officer, was appointed Chief Executive Officer and Mr. Didier Hoch, previously Chairman and Chief Executive Officer, was appointed Chairman of the Board of Directors.

Significant financial transactions and announcement of the Merger

On September 22, 2022, Pherecydes announced the success of its capital increase, launched on September 21, 2022, for a total amount of 3.1 million euros, of which 2.6 million euros from institutional investors and 0.5 million euros from individuals.

On February 15, 2023, Erytech and Pherecydes announced the combination of their two companies (please refer to Section 2.1.7 above for more details on the communication made).

On February 17, 2023, Pherecydes announced the completion of the capital increase for a total amount of 1.5 million euros, fully subscribed by Auriga IV Bioseeds, Ouest Ventures III² and the pool of shareholders represented by Mr. Guy Rigaud, historical shareholders of Pherecydes.

26

The funds raised through this capital increase will provide Pherecydes Pharma with sufficient resources to finance its cash requirements until the completion of the merger, expected no later than June 30, 2023.

On March 30, 2023, Pherecydes presented its 2022 annual financial results. As of December 31, 2022, Pherecydes had cash and cash equivalents of 1 million euros (approximately 1.1 million dollars), compared to 5.4 million euros as of December 31, 2021. In addition to this cash, the capital increase completed on February 17, 2023 for a total amount of 1.5 million euros, is part of the merger project of Pherecydes Pharma into Erytech Pharma announced on February 15, 2023. The current cash position allows Pherecydes Pharma to cover its cash needs until the end of the first half of 2023, when the merger with Erytech is expected.

On May 16, 2023, Pherecydes announced the entering into the Merger Agreement with Erytech on May 15, 2023. In addition, Pherecydes announced that the contribution by Elaia Partners, Go Capital and a pool of Pherecydes shareholders represented by Mr. Guy Rigaud, of 827,132 Pherecydes shares to Erytech in consideration of 3,101,745 newly issued Erytech shares has been approved by Erytech’s board of directors on May 15, 2023, which also approved the appointment of Mr. Didier Hoch and Ms. Leila Nicolas, representing Go Capital, as directors.

The Merger is part of a strategic combination aimed at creating a global leader in phage therapy by capitalizing on the financial resources and teams of both the Absorbed Company and the Absorbing Company to both accelerate and expand Pherecydes’ existing phage therapy development programs, launch new phage candidates and potentially broaden the scope of application to new therapeutic modalities by leveraging both companies’ advanced technology platforms and expertise.

The Merger would close the strategic evaluation process announced by Erytech on several occasions since November 2021, and would represent the outcome of its effort to find strategic alternatives and a new direction for Erytech. Following the failure of its phase 3 trial in pancreatic cancer, Erytech has sought to leverage its corporate structure and capabilities by adding a clinical stage asset to its business in an area of significant unmet need. Antibiotic resistance is a major medical challenge worldwide and the phage therapy programs developed by Pherecydes represent a promising approach to targeting pathogenic bacteria such as S. aureus, E. coli and P. aeruginosa, which together are responsible for more than 800,000 resistant infections per year in the United States and Europe.

Erytech’s capabilities, expertise and assets, and in particular its late-stage clinical oncology experience, would complement and reinforce the efforts of Pherecydes’ teams to help create value. As part of the Merger, it is planned to relocate all teams to Erytech’s premises in Lyon, France, where they will benefit from a location within a major European center in the field of infectious diseases.

27

Erytech and Pherecydes are expected to combine key expertise and capabilities to drive Pherecydes’ research and development programs, an experienced and highly complementary management team, and an international position that provides access to U.S. investors and stakeholders, particularly given Erytech’s listing on Nasdaq. These assets will allow to accelerate the clinical development plan of Pherecydes with international randomized controlled studies, aiming at establishing the clinical proof of concept of phagotherapy.

The shareholders of Pherecydes will receive, in the context of the Merger, Erytech shares, according to an exchange ratio of four (4) shares of Pherecydes for fifteen (15) shares of Erytech (determined as described in Section 3.5 of the Exemption Document). Upon completion of the Merger, the shareholders of Pherecydes will hold approximately 49% of the share capital and voting rights of Erytech³. Please refer to Section 5.5.2 of the Exemption Document for more details.

The Merger will allow to benefit from the complementarity between the resources offered by Erytech and the expertise of Pherecydes, with regard to the opportunities represented by the phage market.

Thanks to Erytech’s current cash position (38.8 million euros as of December 31, 2022), the financial visibility of the Absorbing Company, following the completion of the Merger, would extend to the 3^rd quarter of 2024, with a consolidated unaudited cash position of approximately 41 million euros by December 31, 2022, and would fund multiple clinical milestones in its existing and future programs.

Other potential complementarities and synergies brought by Erytech are:

Pherecydes would bring its ambitious clinical development plan in antibiotic resistance, including a phase II study and several phase I/II clinical studies, and other potential activities: development beyond antibiotic resistance (One Health, cosmetics) and phagogram (IVD diagnostic test).

28

The goal of the new entity in 2023 and 2024 would be to focus on the following objectives:

The pipeline of product candidates following the completion of the Merger is presented below:

This Section includes the main elements required by Article 91 (2) of Directive (EU) 2017/1132 contained in the Merger Agreement, a copy of which is reproduced in full in ANNEX 1 of the Exemption Document.

29

The Merger consists of a merger of Pherecydes into Erytech. The Merger Agreement is governed by French law and in particular by articles L. 236-1 et seq. of the French Commercial Code.

No special benefits are granted in accordance with the provisions of Article 91(2) of Directive (EU) 2017/1132.

The boards of directors of Erytech and Pherecydes have agreed on the terms of the Merger Agreement by decision dated May 5, 2023.

The Merger Agreement was signed on May 15, 2023.

The terms and conditions of the Merger are established on the basis of:

From an accounting and tax perspective, the Merger will be effective retroactively as of January 1, 2023 (the “Effective Date”) in accordance with the provisions of Article L. 236-4 of the French Commercial Code, so that all active and passive transactions carried out by the Absorbed Company from the Effective Date until the Completion Date (as defined below) will be deemed to have been carried out for the benefit of, or at the expense of, the Absorbing Company.

30

Thus:

As the Merger involves the transfer of the universality of the assets of the Absorbed Company to the Absorbing Company, the contributions and the liabilities encumbering these contributions will relate to the generality of the elements composing the assets of the Absorbed Company, even if not specifically designated or omitted in the nomenclature established on the basis of the annual accounts of the Absorbed Company. As a result, this nomenclature is merely declarative and not restrictive.

The Merger and the resulting dissolution of the Absorbed Company will only be completed on the date of satisfaction of the last of the conditions precedent set forth below (the “Completion Date”).

The Merger is subject to the following conditions precedent:

In any event, it is specified that if the conditions precedent are not fulfilled before July 31, 2023 at midnight at the latest, the Merger Agreement will be automatically terminated, without any indemnity on either side, unless both parties waive the Merger Agreement.

31

No modification of the articles of association is planned other than those resulting from the adaptation of the bylaws of the Absorbing Company as a consequence of the Merger, namely:

3.2.1.4 Opinion of the social and economic committee of the Absorbing Company

The social and economic committee of Erytech has been informed about the Merger and has issued a favorable advisory opinion on the Merger on March 20, 2023.

From a tax and accounting perspective, the Merger will take effect retroactively as of the Effective Date, i.e. on January 1, 2023.

From a corporate income tax perspective, the Merger is placed under the preferential regime of article 210 A of the French General Tax Code (Code general des impôts). To this end, Erytech has made, in the Merger Agreement, all the commitments provided for in the said article.

With regards to registration duties, in accordance with articles 635, 1-5° and 816 of the French General Tax Code, the Merger will be registered free of charge within a period of one month following the Completion Date. If applicable, the transfer of any title deed of real estate will however be subject, upon its registration, to a real estate security contribution at the rate of 0.1% on the market value of such real estate, in accordance with articles 879 and 881 K of the same code.

On May 5, 2023, Elaia Partners (acting on behalf of Auriga IV Bioseeds), Go Capital (acting on behalf of Ouest Ventures III) and certain shareholders of the Absorbed Company led by Mr. Guy Rigaud, shareholders representing together approximately 46.81⁴% of the share capital and voting rights of the Absorbed Company, together with the Absorbing Company, entered into a contribution in kind agreement pursuant to which they agreed to contribute, prior to the Completion Date, 827,132 ordinary shares of the Absorbed Company (the “Contributions in Kind”).

32

These Contributions in Kind are made in accordance with the support commitments entered into in the context of the signature of the Memorandum of Understanding, pursuant to which these shareholders of the Absorbed Company have undertaken to contribute these shares before the Completion Date (as defined below in Section 3.2.1.2) in exchange for newly issued Erytech shares, at the same exchange ratio as the Merger.

A share capital increase of the Absorbing Company by issuance of 3,101,745 new Erytech shares as consideration for the contribution of the 827,132 ordinary shares of the Absorbed Company referred to above has been decided by the meeting of the Board of directors of the Absorbing Company held in May 15, 2023 in accordance with the delegation of powers granted by the general meeting of shareholders of the Absorbing Company held on June 24, 2022 (29^th resolution)

Upon completion of the Contribution in Kind, Erytech holds 827,132 shares of Pherecydes, i.e. 10.42% of the share capital and voting rights of Pherecydes, and undertakes to maintain this shareholding unchanged until the Completion Date.

The report of the statutory auditors was filed with the clerk of the Commercial Court of Lyon in accordance with the regulations in force.

The Absorbed Company does not hold any shares of the Absorbing Company to date.

At the close of the Board of directors’ meeting of May 15, 2023, the Board of Directors co-opted Mr. Didier Hoch and the company Go Capital, represented by Mrs. Leila Nicolas, as directors of the Absorbing Company.

As of the date of this Exemption Document, neither the Absorbing Company nor the Absorbed Company has guaranteed each other.

As of the date of this Exemption Document, no agreement has been entered into between the Absorbing Company and the Absorbed Company, except for the (i) Memorandum of Understanding and the (ii) Merger Agreement.

It should be noted that, at the date of its conclusion, the Contribution Agreement, did not constitute a regulated agreement within the meaning of article L. 225-38 of the French Commercial Code.

33

Pursuant to articles L. 225-197-1 and L. 228-98 to L. 228-106 of the French Commercial Code and article 6.3.2 of the regulations of the free share allocation plan adopted by the board of directors of the Absorbed Company on May 19, 2022, the Absorbing Company will automatically replace the Absorbed Company in its obligations towards the beneficiaries of free Pherecydes Shares and the beneficiaries of warrants for subscription to business creator shares (the “BSPCE”).

The rights of the beneficiaries will therefore be transferred to new shares of the Absorbing Company in application of the exchange ratio referred to in Section 3.2.3.2 below, according to the following formalities: the number of shares of the Absorbed Company to which each beneficiary would be entitled in the case of the same allocation plan will correspond to the number of shares of the Absorbing Company to which he would have been entitled under this plan multiplied by the exchange ratio applicable to the shareholders referred to in Section 3.2.3.2 below, the number thus obtained being rounded down to the nearest whole number. It is specified that the beneficiaries of BSPCE and free shares will be notified of the above conditions by the Absorbed Company, before the planned Completion Date.

The other provisions provided for by the regulations and plans for the allocation of free shares and BSPCE, and in particular the provisions relating to the vesting and retention periods, for their remaining duration on the Completion Date, remain applicable to the rights and allocations and to the new shares of the Absorbing Company received in exchange by the beneficiaries.

The extraordinary general meeting of the Absorbing Company called to rule on the Merger will take note of the obligations of the Absorbing Company resulting from this assumption of the commitments of the Absorbed Company and will waive the preferential subscription right to the ordinary shares that will be issued by the Absorbing Company as a result of the exercise of the BSPCE and the definitive allocation of the free shares.

The approval of the Merger will be subject to the decision of the general meeting of the shareholders of Erytech and Pherecydes on June 23, 2023. Please refer to Section 4.3.2 “Resolutions, authorizations and approvals pursuant to which the securities will be created and/or issued” of this Exemption Document.

Auriga Partners (acting on behalf of Auriga Ventures III) and Recordati SpA, which together represent approximately 4.24 % of the share capital and 8.14 % of the voting rights of Erytech, have confirmed their support for the Merger and their commitment to vote in favor of the related resolutions.

Elaia Partners (acting on behalf of Auriga IV Bioseeds), Go Capital (acting on behalf of Ouest Ventures III) and certain shareholders of Pherecydes led by Mr. Guy Rigaud, representing together approximately 46.81% of the share capital and voting rights of the Absorbed Company, have contributed, on May 15, 2023, 827.132 Pherecydes shares to the Absorbing Company in consideration of newly issued 3,101,745 Erytech shares. These shareholders have committed to (i) in their capacity as shareholders of Erytech, vote in favor of the Merger project at the general meeting of shareholders of Erytech and (iii) in their capacity as shareholders of Pherecydes, vote in favor of the Merger project at the general meeting of shareholders of Pherecydes.

34

It is specified that, in accordance with Erytech’s press release dated May 16, 2023, that in view of the next general meeting of the shareholders of Erytech, Erytech intends to file a request with the President of the Commercial Court of Lyon to appoint an ad hoc agent (mandataire ad hoc).

The ad hoc agent will represent the shareholders absent at the General Meeting to ensure that the required quorum is satisfied and the shareholders’ general meeting is allowed to validly resolve on all resolutions set forth on the agenda.

In accordance with the terms of the order to be issued by the President of the Commercial Court of Lyon, the ad hoc agent will exercise the voting rights attached to the shares of the absent shareholders to the extent necessary to reach the required quorum, so that its vote will be neutral (proportion of 50% positive votes and 50% negative votes with respect to ordinary resolutions; proportion of 2/3 positive votes and 1/3 negative votes with respect to extraordinary resolutions). Consequently, the voting rights exercised by the ad hoc agent will have no impact on the outcome of the vote of the general meeting of shareholders of Erytech.

Ruling on the joint request of Erytech and Pherecydes, the President of the Commercial Court of Lyon, by order of February 28, 2023, has appointed the firm Finexsi as Merger Auditor, represented by Mr. Christophe Lambert.

Please refer to Section 1.3 “Expert’s Statement or Report” of the Exemption Document.

The Erytech shares will be allocated to the Pherecydes shareholders as consideration for the Merger.

As consideration for the Merger, the Absorbing Company will issue 26,575,893 new shares based on the exchange ratio retained in the context of the Merger which is fifteen (15) shares of the Absorbing Company for four (4) shares of the Absorbed Company.

The Absorbed Company holds 25,142 of its own shares as of the date hereof, i.e. 0.32% of its share capital.

Pursuant to the provisions of Article L. 236-3 II of the French Commercial Code, neither the exchange of the shares of the Absorbed Company that will be held by the Absorbing Company as a result of the Contributions in Kind (as defined in the Merger Agreement), nor the exchange of the treasury shares held by the Absorbed Company, which will be cancelled by operation of law on the Completion Date, will take place.

35

As consideration for the Merger, the Absorbing Company will proceed, on the Completion Date, pursuant to the exchange ratio, to an increase of its share capital by an amount of 2,657,589.30 euros, by the creation of 26,575,893 new shares having the same nominal value (i.e., 0.10 euro each) as the existing shares (the “New Shares”), which will be directly allocated to the shareholders of the Absorbed Company, other than the Absorbing Company, in accordance with the applicable exchange ratio.

It is specified that the final number of New Shares to be issued and, accordingly, the nominal amount of the resulting share capital increase will be adjusted by operation of law according to the exact number of Pherecydes shares to be remunerated pursuant to the Merger, in case, among other things, the amount of the New Shares to be issued and the nominal amount of the resulting share capital increase would be adjusted as a result of an inter-company transaction between the date of the Merger Agreement and the Completion Date.

No fractional shares will be issued. Each shareholder of the Absorbed Company will be credited with a number of ordinary shares of the Absorbing Company corresponding to the integer equal to or immediately lower than the product of the number of shares of the Absorbed Company that he/she will hold at the Completion Date by the exchange ratio provided in Article 14 of the Merger Agreement.

It is specified that the holders of shares of the Absorbed Company who do not own the necessary number of shares of the Absorbed Company to obtain a whole number of shares of the Absorbing Company will receive a cash payment for the fractional part. The amount of this cash payment will be determined as follows:

The New Shares, that will be immediately assimilated to the existing shares of the Absorbing Company, will carry dividend rights as from their date of issue and will give the right to the benefit of all distributions of dividends or reserves decided as from this date. A double voting right will be attributed in accordance with the legal conditions to all fully paid-up shares for which proof of registration for at least two years is provided. The New Shares will all be negotiable as soon as the capital increase of the Absorbing Company remunerating the merger is completed, in accordance with article L. 228-10 of the French Commercial Code, and will immediately be the subject of an application for admission to trading on the regulated market of Euronext Paris.

36

It is specified that, on the Completion Date, the New Shares will not be registered with the Securities Exchange Commission or be the subject of an application for admission to trading on Nasdaq. Such registration shall be made within twelve (12) months after completion of the Merger.

Pursuant to the regulation of the French accounting standards authority (Autorité des normes comptables) n° 2014-03 of June 5, 2014, relating to the general chart of accounts as last amended by the ANC regulation n° 2022-01 of March 11, 2022, the contributions made in the context of the Merger shall be valued on the basis of their fair market value, determined according to the valuation methods described in Section 3.2.3.6 of this Exemption Document.

Designation and value of the contributed assets

The Merger of the Absorbed Company includes all the assets of this company for their real value as determined hereinafter (the net book value being given for information purposes only):

37

The fair market value of the assets included in the contribution therefore amounts to 22,231,338 euros.

Designation and value of liabilities supported

The Merger of the Absorbed Company is granted and accepted in consideration of the assumption by the Absorbing Company of all the liabilities of the Absorbed Company, namely:

38

The total amount of the liabilities included in the contribution is therefore supported for an amount of 5,693,952 euros.

The net assets contributed by the Absorbed Company and remunerated by the Absorbing Company pursuant to article L. 236-3 II of the French Commercial Code therefore amount to 16,537,386 euros.

(b) Details of the calculation of the merger bonus

The difference between the net assets contributed by Pherecydes of 16,537,386 euros (i.e. net assets contributed of 16,479,810.89 euros after deduction of the treasury shares) and (i) the completion of the Contribution in Kind (1,894,132 euros) and (ii) the nominal amount of the capital increase of Erytech relating to the Merger (2,657,589.90 euros, accompanied by a total compensation of 0.42 euros) i.e. 12,099,841.12 euros, represents the merger premium and will be credited to an account “merger premium”.

There are no future events that condition the grant of additional securities to the shareholders of the Absorbed Company in connection with the Merger.

The exchange ratio retained for the issuance of 26,575,893 newly issued ordinary shares by the Absorbing Company to the benefit of the shareholders of the Absorbed Company, was assessed according to a multi-criteria approach based on valuation methods usually used for the valuation of companies in the healthcare sector.

39

A summary description of these methods can be found in Annex 14.1 of the Merger Agreement (in Annex 1 of the Exemption Document).

No break-up fee or any other penalty has been provided for in the Merger Agreement in the event that the Merger is not completed.

No third party notification or authorization request is required for the completion of the Merger, except for the approval of the extraordinary general meeting of the Absorbing Company and the Absorbed Company (please refer to Section 3.2.1. of the Exemption Document).

The implementation of the Merger does not require any specific structure for its financing that should be the subject of any presentation.

40

In addition to the risk factors relating to the Group and its business described in Chapter 2 “Facteurs de risque” of the Erytech 2022 Universal Registration Document , the investor is invited to take into account the following risk factors and other information contained in the Exemption Document before deciding to invest in Erytech shares. An investment in the shares of Erytech involves risks.

As of the date of the Exemption Document, Erytech has not identified any significant risks other than those described in the Erytech 2022 Universal Registration Document and the Exemption Document.

The risk factors described below are specific to the Merger and are presented from the most important to the least important. The risk factors related to the equity securities to be issued by Erytech in connection with the Merger are set forth in Section 4.1 “Risk Factors Related to Equity Securities” of the Exemption Document.

Risk related to the absence of variation of the number of new Erytech shares issued in consideration of the Merger with respect to the evolution of the share price of the Erytech and Pherecydes

As at the date of signature of the Merger Agreement, the exchange ratio was set at four (4) shares of Pherecydes for fifteen (15) shares of Erytech (as indicated in Section 3.5 of the Exemption Document). As no adjustment mechanism is provided for, the exchange ratio will remain unchanged and the Merger will be completed even if the market prices of the Erytech and/or Pherecydes shares would change after the execution of the Merger Agreement. However, the share prices of the Erytech and/or Pherecydes shares could vary or have varied significantly upwards or downwards on the Completion Date as compared to the date on which the exchange ratio of the Merger was set by the respective boards of directors of Erytech and Pherecydes on June 23, 2023. The Merger will therefore be completed at the initial exchange ratio even if the share prices of Erytech and/or Pherecydes would change significantly after the execution of the Merger Agreement.

41

Impact of the Merger on the share price of Erytech

The completion of the Merger could have an adverse effect on the share price of Erytech on the regulated market of Euronext Paris and on the trading price of the Erytech ADS on Nasdaq.

A significant and sustained decline in the share price of Erytech could have a material adverse effect on Erytech’s business, prospects, results, financial condition, reputation and development.

Risk related to the non-realization of certain conditions precedent

The completion of the Merger is subject to the satisfaction of several conditions precedent provided for in the Merger Agreement, namely:

If these conditions are not fulfilled by midnight on July 31, 2023 at the latest, the Merger Agreement will be deemed to be null and void, without any indemnity on either side, unless waived by both Parties. The Merger would therefore not be completed and the development plans presented could not be realized immediately. Such events could have a material adverse effect on Erytech’s and Pherecydes’ business, results, financial condition and prospects.

Risk related to the integration of the activities of the two companies, to the costs related to integration and to the realization of synergies

The success of the Merger operation will be built as much in the preparation of the envisaged operation as in the integration process that will follow the legal completion of this operation. The two key points will be the ability of the new merged group to realize the synergies and to integrate the respective cultures. The realization of synergies will not be automatic. The new merged group may not have the tools and organization in place to identify the best practices of Erytech and Pherecydes. Moreover, a certain operational integration is necessary to obtain cost reductions, but it is not excluded that this integration could lead to a destruction of a certain value and competences necessary to its competitiveness. Indeed, the group thus formed might not have, or might not have sufficiently, evaluated, developed and worked on the compatibility of the organizations, the degree of transformation they can support and the management of this process. It could be difficult to reconcile the operational requirements and the strategic vision of the new entity. In addition, the Merger will lead to the relocation of Pherecydes’ activities currently located in Nantes to Erytech’s premises in Lyon, which may lead to the departure of certain key employees. The occurrence of one or more of these risks could have a significant adverse effect on the business of the new merged group, its results, its financial condition and its prospects.

42

Risk related to the need to retain management and key personnel following the Merger

The success of the new group formed as a result of the Merger will largely depend on its ability to retain and attract key executives and personnel of both companies. The inability of the merged group to retain, attract and retain key personnel could prevent it from achieving its objectives overall and thus have a material adverse effect on its business, results, financial condition and prospects.

Risk related to the U.S. regulatory compliance due to dual listing

As a result of the Merger, the shareholders of Pherecydes will become shareholders of a dual listed company. The listing of its shares, in the form of American Depositary Shares (ADS), in the United States on the Nasdaq Stock Market results in the Company being subject to a series of standards and regulations, including the reporting requirements of the Securities Exchange Act. All information concerning Pherecydes’ business will therefore be subject to regulatory disclosure requirements. Legal proceedings could be initiated by competitors or third parties on the basis of this information concerning the clinical programs developed by Pherecydes. If such claims are successful, the company’s business and operating results could be affected. Even if such legal actions do not result in a conviction against the Company, these proceedings, and the time and resources required to resolve them, may require the Company to use resources that should have been allocated to the company’s business. This would have a material adverse effect on the company’s business, financial condition, results, reputation or development.

The fund Auriga IV Bioseeds, a professional private equity fund represented by its management company Elaia Partners, a simplified joint stock company (société par actions simplifiée), whose registered office is located at 21 rue d’Uzès, 75002 Paris, France, registered with the Paris Trade and Companies Register under number 443 990 668, shareholder of Pherecydes, and the company Auriga Partners, a simplified joint stock company (société par actions simplifiée), whose registered office is located at 250 B rue du Faubourg Saint-Honoré, 75008 Paris, registered with the Paris Trade and Companies Register under number 419 156 351, shareholder of Erytech, are two separate and distinct entities, and invest from time to time in the same business sectors.

Elaia Partners and Auriga Partners have partnered in several joint investment projects.

Franck Lescure, partner at Elaia Partners and member of the board of directors of Pherecydes, was previously a partner at Auriga Partners and was a member of the board of directors of Erytech from December 2006 to January 2013.

Please refer to paragraph 3.2.3 “Merger Consideration” of this Exemption Document.

43

The risk factors described below are listed from most to least significant.

The present section of the Exemption Document identifies the risks specific to the issuance of new equity securities that may adversely affect Erytech and its equity securities.

Risk of an influx of Erytech shares for sale on the market

The shareholders of Pherecydes who will receive Erytech shares as consideration for the Merger may wish to sell their Erytech shares, which would result in an increase in the number of Erytech shares available for sale and affect the Erytech’s share price. The Company cannot predict the possible effects on the market price of the Company’s shares of potential sales of shares by its shareholders.

Risk related to the issuance of new shares in the context of the Merger resulting in a dilution of the existing shareholders of Erytech

The issuance of the new Erytech shares in the context of the Merger involves the issuance of 29,677,638 shares (of which 26,575,893 in respect of the Merger and 3,101,745 shares pursuant to the Contribution in Kind) to the benefit of the shareholders of Pherecydes, whereas the share capital of Erytech was composed of 31,018,553 shares before the Contribution in Kind. A shareholder holding 1% of the share capital of Erytech prior to the Contribution in Kind will therefore hold, upon completion of the Merger, 0.51% of the share capital of Erytech. The dilution that may result from the issuance of the new Erytech shares is described in Section 4.5 of this Exemption Document.

Risk related to the volatility and liquidity of the shares following the Merger

The stock markets have experienced significant fluctuations in recent years that have often been unrelated to the results of the companies whose shares are traded. Market fluctuations and health, geopolitical and economic conditions could increase the volatility of Erytech’s shares. Erytech’s share price could fluctuate significantly in response to various factors and events, including the Merger.

As an example, upon the announcement in August 2022 of the discontinuation of activities to submit an application for approval for Graspa in the treatment of patients with ALL, the share price fell by 25% compared to the average of the previous 20 share prices. In addition, in the event that liquidity for the market of shares admitted to trading on Euronext Paris is not sustained, the price of the ordinary share could be more volatile and it would become more difficult to buy or sell ordinary shares on the Euronext Paris market than to buy or sell ADS on the Nasdaq market. The dual listing of Erytech’s shares in two different currencies (euro and US dollar) opens the possibility of an arbitrage strategy between the two stock exchanges that could have an impact on the respective prices of the ADSs and the shares. It is however specified that the New Shares will neither be registered with the Securities and Exchange Commission (the “SEC”) nor be the subject of an application for admission to trading on Nasdaq. Such registration shall be made within twelve (12) months after completion of the Merger

44

Erytech certifies that, in its opinion, Erytech’s net working capital is sufficient to meet its current obligations for a period of twelve (12) months as of the date of issuance of the Exemption Document and that, after taking into account the completion of the Merger, Erytech’s working capital will be sufficient to meet its current obligations for a period of twelve (12) months as of the date of issuance of the Exemption Document.

Descriptive and financial information about the material effects that the Merger will have on its financial statements is presented in Section 5.6 of the Exemption Document.

The 26,575,893 New Shares issued as consideration for the Merger, the admission of which to trading on Euronext Paris is requested, correspond to the maximum number of new shares with a nominal value of 0.10 euro. The dilution that may be generated as a result of the issuance of these new shares is presented in Section 4.5 of the Exemption Document.

The New Shares will carry current dividend rights and will be entitled to all distributions decided by the Absorbing Company as from their issue.

They will immediately be the subject of an application for admission to trading on the regulated market of Euronext in Paris (compartment C), on the same quotation line as the existing shares under the same ISIN FR0011471135, at the earliest on the date indicated in the indicative timetable set out in Section 3.2.6 of the Exemption Document.

It is specified that, on the Completion Date, the New Shares will not be registered with the SEC nor will they be the subject of an application for admission to trading on Nasdaq. Such registration shall be made within twelve (12) months after completion of the Merger.

The new shares will be denominated in euro.

The resolutions of the boards of directors of the Absorbing Company and the Absorbed Company dated May 5, 2023, authorizing the signature of the Merger Agreement are set forth in Annex 1 of this Exemption Document.

The General Meeting of the Absorbed Company will meet on June 23, 2023 to approve among others the resolutions set in Annex 3 of the Exemption Document, including the extraordinary resolution n° 5 and n°6 relating to the Merger.

The General Meeting of the Absorbing Company will meet on June 23, 2023 to approve among others the resolutions set out in Annex 3 of the Exemption Document, including the extraordinary resolutions n°17 to n°20 relating to the Merger.

45

No clause in the articles of association limits the free trading of the shares comprising the capital of the Absorbing Company.

No takeover bid was initiated for the shares of the Absorbing Company during the year ended December 31, 2022, nor during the current year.

The 26,575,893 New Shares issued in consideration of the Merger will be immediately admitted to trading on the regulated market of Euronext Paris (“Euronext Paris”) (compartment C), on the same quotation line as the existing shares under the same ISIN FR0011471135, it being specified that these shares will be admitted to trading at the earliest on June 29, 2023, as indicated in the indicative timetable set forth in Section 3.2.7 of this Exemption Document.

The new shares may be converted into ADS pursuant to the terms of the Deposit Agreement between Erytech and Bank of New York Mellon. Once converted, the ADS may be traded on Nasdaq in the same way as the existing ADS. The conversion into ADS may not be completed until 12 months after the closing of the Merger unless, following the completion of the Merger, the Company files a registration statement with the SEC to allow the registration of the ADS. As part of the Memorandum of Understanding, it was agreed that the company would use its best efforts to file a registration statement within 12 months following the Merger.

As of the date of this Exemption Document, there are no firm commitments with entities that would like to act as intermediaries on the secondary markets and guarantee the liquidity of the new shares by acting as buyers and sellers.

As of the date of the Exemption Document, there are no lock-up agreements relating to the shares of the Absorbing Company.

For information purposes, the impact of the issuance of the New Shares in the context of the Merger on:

46

(x) prior to the completion of the Contribution in Kind and to the issuance of the New Shares (calculated on the basis of the number of shares composing the share capital of the Absorbing Company and of the number of voting rights as of April 30, 2023) and (y) subsequent to the completion of the Contribution in Kind and of the Merger is as follows:

^(a) : after the Merger, the 684,273 shares to which the 123,950 warrants issued by the Absorbed Company prior to the present and which were, prior to the signature of the Memorandum of Understanding, exercisable and in the money, and the 58,523 ordinary shares allocated free of charge by the Absorbed Company prior to the present are taken into account in the calculation of the number of shares and voting rights of the Absorbing Company on a diluted basis.

^(b) : after the Merger, the number of shares and voting rights of the Absorbing Company on a diluted basis does not take into account the shares to which all the dilutive instruments issued by the Absorbing Company give entitlement, as these were not in the money on the date of signature of the Memorandum of Understanding, it being specified that the warrants attached to the ABSAs are no longer exercisable as of the date of the Registration Document (the dilutive instruments of the Absorbing Company are described in Sections 3.1.2.1.3 and 3.3 of the Erytech 2022 Universal Registration Document).

Insofar as Pherecydes does not have double voting rights, its shareholders cannot benefit from this double voting right immediately after the completion of the Merger (even if they meet the two-year holding period at the time of the exchange) and will have to wait for the expiration of the holding period provided for in the articles of association of Erytech to be able to exercise the double voting right, since they cannot claim the benefit of article L. 225-124, paragraph 2 of the French Commercial Code.

47

The chart below shows the structure of the Absorbing Company after the completion of the Merger:

* The new corporate name will be voted at the extraordinary general meeting of June 23, 2023.

4.5.2 Concurrent offering of equity securities of the same class

None

In the context of the Merger, ODDO BHF SCA acted as financial advisor.

The strategy and objectives of Erytech after completion of the Merger are described in Section 1.2 “Stratégie du Groupe” of the Erytech 2022 Universal Registration Document and in Section 3.1 of the Exemption Document.

It is specified that, as of May 5, 2023, Bpifrance has given its consent to the continuation within the Absorbing Company of the following contracts entered into by the Absorbed Company: (i) the State-guaranteed loan agreement dated April 27, 2021 for an amount of 2 million euros, as amended in January 2022 in order to benefit from an additional one-year deferral of repayment and a four-year repayment thereafter and (ii) the agreement dated February 22, 2022 for the financing of the PhagEcoli program for an amount of 1,687,800 euros, divided 60% in the form of a grant and 40% in the form of a reimbursable advance, to be paid at each milestone and conditional on the provision of certain elements by Pherecydes Pharma.

In addition, on May 5, 2023, (i) Société Générale has agreed to the continuation of the State-guaranteed loan entered into by the Absorbing Company on November 5, 2020, for a principal amount of 5 million euros and (ii) Bpifrance Financement has agreed to the continuation of the State-guaranteed loan entered into by the Absorbing Company on November 10, 2020, for a principal amount of 5 million euros.

As of the date of the Exemption Document, there are no other material contracts entered into within the Absorbing Company and/or within the Absorbed Company that would be impacted by the Merger.

48

None.

Under the terms of the Memorandum of Understanding, and as announced in the press releases of Erytech and Pherecydes dated the February 15, 2023 (please refer to Sections 2.1.7 and 2.2.7), upon completion of the Merger, Mr. Jean-Paul Kress, Chairman of Erytech, will resign from his position and Mr. Didier Hoch, Chairman of Pherecydes, will become Chairman of the Board of Directors of Erytech.

Mr. Thibaut du Fayet, currently Chief Executive Officer of Pherecydes, will become Chief Executive Officer of Erytech, while Mr. Gil Beyen, currently Chief Executive Officer of Erytech, will become Vice-Chairman of the Board of Directors of Erytech (and will remain Executive Chairman of ERYTECH Pharma, Inc., Erytech’s U.S. subsidiary). Mr. Eric Soyer will remain Chief Operating Officer and Chief Financial Officer of Erytech. Mr. Jérôme Bailly will retain his position as Deputy Chief Executive Officer following the Merger.

On May 15, 2023, the Board of Directors of the Absorbing Company, which approved the final completion of the Contributions in Kind, also co-opted Mr. Didier Hoch and the company Go Capital, represented by Mrs. Leila Nicolas, as directors of the Absorbing Company. In addition, Mrs. Mélanie Rolli and Mr. Luc Dochez have resigned from their positions on the Board of Directors of Erytech. These co-optations are decided subject to ratification by the next annual general meeting of Erytech and for the remaining term of office of Mrs. Mélanie Rolli and Mr. Luc Dochez. Mr. Sven Andréasson will resign from his position as director upon completion of the Merger.

It is also specified that the composition of the committees of the board of directors will be modified to take into account new appointments and resignations.

49

Following the completion of the Merger, the members of the board of directors of Erytech will be the following:

Erytech and Pherecydes have agreed to establish a strategic steering committee that supervises the execution of the Memorandum of Understanding, and in particular the implementation of the Merger and the operational integration of the two companies. This strategic steering committee is composed of two representatives of Pherecydes, namely Mr. Didier Hoch and Mr. Thibault du Fayet, and two representatives of Erytech, namely Mr. Gil Beyen and Mr. Eric Soyer. It meets at least every two weeks since the signature of the Memorandum of Understanding and whenever an emergency situation requires it.

Didier Hoch, director

Didier Hoch was coopted as a director of Board of directors of Erytech during its meeting on May 15 2023. He served as Chairman of the former Supervisory board of Pherecydes and then, since January 2019, as Chairman of the Board of Directors. Didier Hoch is a physician and is also a director of a listed company, OSE Immunotherapeutics, and was previously director of DBV Technologies and Genticel. From 2011 to 2013 he was Chairman of Pevion Biotech and then from 2013 to 2018 of the Biovision Forum and of the startup gas pedal “Big Booster”. Didier Hoch was, from 2000 to 2010, Chairman of Sanofi-Pasteur- MSD, a joint-venture dedicated to vaccines, between Sanofi & Merck. Didier Hoch has also held various management positions at Rhône Poulenc Rorer, then Aventis (“VP Middle East -Africa”, Vice President Middle East & Africa). Former President of the Vaccine Europe association of vaccine manufacturers “Vaccine Europe” and Chairman of the Biotechnology Committee of LEEM.

50

Robert Sebbag, director

Robert Sebbag was a member of the former Supervisory board of Pherecydes and then, since December 2020, a member of the Board of Directors. Robert Sebbag is a physician and a member of the Paris Hospitals’ Infectious and Tropical Diseases Department at the Pitié Salpêtrière Hospital. He is also director and founding member of Action Contre la Faim and director of Fondation Mérieux. From 2006 to 2016 he was Vice President Access to Medicines at Sanofi. Previously he held various positions at Rhône Poulenc Santé, Fondation Elf, and Aventis-Pasteur. Former member of the Executive Committee of the CEO round table of the Gate Foundation and Director of Leem (Les entreprises du médicament).

Eric Leire, director

Eric Leire is physician and currently chairman and chief executive officer of Genflow Biosciences, Eric Leire is also a director of listed and non-listed biotechnology companies (Immunethep, BSIM Therapeutics and Inhatarget Therapeutics). Dr. Leire has served as CEO of several publicly and privately held US biotechnology companies. He has contributed to several IPOs of biotechnology companies on various markets (OMX.Nasdaq; OTC.QB and Nasdaq). He was a research partner at the Harvard AIDS Institute and partner at Biofund Venture Capital. He has an MD from the University of Grenoble and an MBA from HEC and Kellogg School of Management, Northwestern University. He is also the inventor of several patents in the pharmaceutical field.

GO Capital SAS, represented by Leila Nicolas, director

GO Capital SAS, represented by Leila Nicolas, was co-opted as a director by the Board of directors of Erytech during the meeting of the Board of directors on May 15, 2023 and served on the former Supervisory board and then as a director of the Board of directors between December 2017 and June 2023. Leila Nicolas started her career in 2004 as a product manager at Bayer Schering Pharma in the field of multiple sclerosis and oncology. She then joined the Biotechnology and Life Sciences world as strategic marketing manager of a start-up in Alsace (Polyplus-transfection). Leila Nicolas concluded several licensing agreements and acquired a strong sensitivity to intellectual property. Leila Nicolas then participated in the creation of a company that develops and sells environmental health analysis kits before joining Go Capital in late 2013.

Gil Beyen, Chief Executive Officer

Gil Beyen is Chief Executive Officer of Erytech since May 2013 and served as Erytech’s Chairman of the Board from May 2013 until June 2019. Gil Beyen has assisted Erytech since 2012 as a consultant and also served as Chairman of the Supervisory Board of Eyrtech from August 2012 to May 2013. Between 2000 and 2013, Mr. Beyen was Chief Executive Officer and Director of TiGenix (Euronext: TIG), a company he co-founded. He previously served as the head of the Life Sciences division of Arthur D. Little, an international management consulting firm, in Brussels. Mr. Beyen holds a MSc in Bioengineering from the University of Leuven (Belgium) and an M.B.A. from the University of Chicago.

51

Hilde Windels BV, represented by Hilde Windels, director

Hilde Windels has served as a member of the board of directors since 2014 and has served as the representative of Hilde Windels BV, the legal entity that holds this seat, since 2017. She has over 20 years of experience in corporate finance, capital markets and strategic initiatives. She currently serves as Chief Executive Officer of Antelope Dx BV and Director of MDx Health NV and Celyad SA. Prior to Antelope Dx BV, she was executive chairman of the board of directors and co-Chief Executive Officer of Mycartis NV, a private immune diagnostics company in Belgium and a spin-out of Biocartis Group NV. Ms. Windels initially joined Biocartis in August 2011 as its Chief Financial Officer, a position she held until September 2015 when she was appointed co-Chief Executive Officer, a position she held until early 2017, when she became interim Chief Executive Officer of Biocartis until September 2017. From early 2009 to mid-2011, she worked as an independent chief financial officer for several private biotechnology companies. Ms. Windels served as Chief Financial Officer of Devgen from 1999 to 2008 and as a member of its board of directors from 2001 to 2008. Ms. Windels holds a Masters in Economics from the University of Leuven (Belgium).

Martine Ortin George, director

Martine Ortin George has served as a member of the board of directors since 2014. Doctor of Medecine, Martine George has extensive experience in the United States in clinical research, medical affairs and regulatory matters with both large and small oncology companies. She currently serves as principal and senior executive consultant-life sciences for Global Development Inc. Dr. George held the position of Vice President in charge of Global Medical Affairs for Oncology at Pfizer from 2010 to 2015. Previously, Dr. George held the positions of Senior Vice President and Chief Medical Officer at GPC Biotech and Senior Vice President, Head of the Oncology Department at Johnson & Johnson. She is a qualified gynecologist and oncologist, trained in France and in Montreal. Dr. George began her career as Chief of Service at the Institut Gustave Roussy (France), was a visiting professor at the Memorial Sloan Kettering Cancer Center, and then held positions of increasing responsibility at Lederle Laboratories (a predecessor company to Pfizer Inc.), Sandoz (now a division of Novartis AG) and Rhône-Poulenc Rorer (today part of Sanofi).

Philippe Archinard, director

Philippe Archinard has served as a member of the board of directors since 2013 and was previously a member of the Supervisory Board from 2007 to 2013. Dr. Archinard is Deputy CEO, Innovation and Scientific Partnerships of the Institut Mérieux. He was General Manager, Chief Executive Officer and director of Transgene from 2004 to 2020, after spending 15 years in various senior positions with bioMérieux, including directing its U.S. subsidiary. Prior to joining Transgene, he served as chief executive officer of Innogenetics N.V., from 2000 to December 2004. Dr. Archinard is a chemical engineer, holds a Ph.D. in biochemistry from the University of Lyon (France), and completed Harvard Business School’s Program of Management PMD.

Guy Rigaud, observer

Guy Rigaud has 30 years of experience in private equity in more than 300 young regional companies (more than half of them in the technology sector). Founder and chairman of the Board of directors of Rhône Alpes Création from 1990 to 2012, Guy Rigaud has participated in five IPOs on Euronext in Paris and two on Nasdaq (in the context of industrial disposals). Guy Rigaud was a member of the Board of directors for 12 years of the April Group (insurance), a company listed on the regulated market of Euronext in Paris. Since 2012, Guy Rigaud is the founder and Managing Partner of a seed capital fund created with four family offices.

52

To the best of Erytech’s knowledge, there is no conflict of interests between the duties performed on behalf of the Absorbing Company by the members of its administrative and management bodies and the private interests or other duties of these members.

To the best of Erytech’s knowledge, there are no restrictions accepted by the members of the administrative and management bodies of Erytech regarding the transfer, within a certain period of time after the Merger, of the equity securities of the Absorbing Company that they hold.

As of the date of the Exemption Document, the Absorbing Company complies with the Middlenext code, as detailed in Section 3.1.1.1 “La mise en oeuvre du Code Middlenext par la Société” of the Erytech 2022 Universal Registration Document. Upon completion of the Merger, the new entity intends to comply with the Middlenext code.

In case of appointment of new corporate officers or renewal of the mandate of a corporate officer in the context of the definitive completion of the Merger, the compensation policy described in section 3.1.2.2 “Politique de rémunération des mandataires sociaux pour l’exercice 2023” of the Erytech 2022 Universal Registration Document will be applicable to them mutatis mutandis, subject to a possible decrease of the fixed, variable or exceptional remuneration decided by the board of directors and/or adjustments of certain other elements of remuneration according to the profile of the concerned persons.

The Absorbing Company intends to adjust the performance criteria upon completion of the Merger.

The following table presents the capital structure of the Absorbing Company after completion of the Merger on the basis of the shareholding structure of the companies following the completion of the Contributions in Kind:

53