Transgene : March 10, 2021 - Significant milestones achieved on all drug candidates in 2020 and financial visibility until 2022

PRESS RELEASE

2020 Full-year results and business update

Significant milestones achieved on all drug candidates in 2020 and financial visibility until 2022

• TG4050: first patients treated in two clinical trials of the novel individualized immunotherapy based on the myvac® technology - First data expected in 4Q 2021
• TG4001: expanded randomized Phase II trial to start in HPV-positive anogenital cancers, based on encouraging Phase Ib/II data
• BT-001: the first candidate from the Invir.IO™ platform has entered the clinic
• Financial visibility until 2022 following the partial sale of the stake in Tasly BioPharmaceuticals in 2020

Conference call in English scheduled today at 6:00 p.m. CET - Video conference in French on March 10

at 10:00 a.m. CET (details at the end of the release)

Strasbourg, France, March 10, 2021, 5:45 p.m. CET - Transgene (Euronext Paris: TNG), a biotech company that designs and develops virus-based immunotherapies for the treatment of cancer, today publishes its financial

results for 2020 and provides an update on its product pipeline.

Hedi Ben Brahim, Chairman and Chief Executive Officer of Transgene since January 1, 2021, commented:

"It is a great honor to join Transgene as Chairman and Chief Executive Officer at the beginning of 2021, taking over from Philippe Archinard. Over the last several months, Transgene has delivered multiple significant milestones, particularly from our new cutting-edge platforms myvac® and Invir.IO™ as we have continued to operate successfully despite the Covid-19 pandemic.

We treated the first patients with TG4050, our individualized immunotherapy based on the myvac® technology. This achievement illustrates how Transgene is positioning itself at the forefront of innovation globally by developing new solutions that could deliver important benefits for patients, clinicians and potential pharmaceutical partners. This customized immunotherapy is particularly promising, and I look forward to reporting the first data from TG4050 in the fourth quarter of 2021.

The very encouraging results with TG4001 which we announced in 2H 2020, have allowed us to rapidly initiate a Phase II randomized trial. The protocol of this study has already been approved in the U.S. and we expect patient inclusion to start in the coming months, with the aim of providing the first clinical results around the end of 2022. This acceleration of our development is also reflected in the progress we made with BT-001, the first oncolytic virus of our Invir.IO™ platform to enter the clinic and supported by a very exciting preclinical data set. We have also seen another clinical oncolytic virus candidate TG6002 advance and deliver first promising translational data.

With financial visibility until 2022, we have the funds needed to deliver the important clinical results we expect in 2021 and 2022. Our strategy aims to leverage Transgene's exciting new drug candidates, notably through large- scale partnerships, to generate significant value for our shareholders. I am very confident that the globally competitive product pipeline that we have today will allow us to deliver on our ambitious goals."

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GLOBAL TECHNOLOGY LEADERSHIP WITH THE MYVAC® PLATFORM AND THE THERAPEUTIC VACCINE TG4050

Transgene is developing an individualized immunotherapy based on multiple advanced genetic engineering technologies that have been developed by the company. TG4050 is the first drug candidate based on the myvac® platform. Together with NEC, Transgene has set up a customized approach that combines its expertise in viral engineering with NEC's artificial intelligence capabilities. NEC's algorithms enable the customization of the treatment for each patient, by indicating the most relevant targets (patient-specificneoantigens).

The Phase I clinical trials assessing TG4050 started in January 2020 in Europe and in the United States. The first patients have been treated in these two clinical trials (ovarian and oropharyngeal cancers). NEC is financing 50% of these studies. The first data are expected in the fourth quarter of 2021.

The Company has set up an in-house production unit dedicated to the manufacturing of the individualized clinical batches of TG4050 needed for each patient. This unit is operational and complies with good manufacturing practice (GMP) norms.

The myvac® platform integrates leading-edge innovations that are based on Transgene's technological leadership in individualized immunotherapies.

• Data validating the vaccine design principle and the underlining accuracy of the algorithm and AI used to personalize TG4050 were presented at the AACR congress (June 2020).
• Transgene has implemented the first block chain solution dedicated to the traceability of this personalized treatment in clinical trials. This solution monitors and orchestrates all of the processes related to the design and manufacturing of Transgene's individualized therapeutic vaccine TG4050.
• Transgene has set up a translational research program that includes a number of very innovative genomic and transcriptomic analyses. The goal is to characterize the effect of the treatment and identify predictors of response to TG4050 in the tumor and the genome environment that may impact each patient's response to the vaccine. These data are important as they could lead to an optimized and accelerated development pathway for TG4050.

RANDOMIZED PHASE II TRIAL OF TG4001

IN HPV16-POSITIVE ANOGENITAL CANCERS TO START,

BASED ON PROMISING INITIAL DATA FROM PHASE IB/II

Transgene has amended the initial Phase Ib/II trial protocol to allow the more rapid start of this randomized Phase II study comparing the efficacy of TG4001 + avelumab versus avelumab monotherapy. This trial will be supported by a continuing collaboration with the alliance of Merck KGaA, Darmstadt, Germany, and Pfizer, which is supplying avelumab. Transgene retains all rights to TG4001.

The trial will focus on patients with recurrent or metastatic HPV16-positive anogenital cancer without liver metastases. This patient population, without liver metastases, was shown in the Phase Ib/II study to derive improved clinical benefit from the combination regimen.

In spite of recent progress, median overall survival is less than 11 months with chemotherapy and immune checkpoint inhibitors. The 25,000 patients who are diagnosed with these diseases every year (U.S., Europe 27, UK) with these HPV16-positive malignancies still need better treatment options.

Transgene received U.S. FDA clearance of the revised protocol under an IND for TG4001. The submission of the amended protocol has been initiated in Europe (France and Spain) where clinical sites that participated in the Phase Ib/II part study are ready to resume patient inclusion after regulatory approval. Patient enrollment is expected to start in 2Q 2021.

Transgene expects to communicate the interim analysis data around the end of 2022. This timeline is based on patient enrollment starting in 2Q 2021 and there being no major impact on recruitment from the Covid-19pandemic.

Transgene today issued a press release providing more background on this TG4001 trial.

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BT-001, THE FIRST ONCOLYTIC VIRUS BASED ON INVIR.IO™, HAS ENTERED THE CLINIC AND FIRST OBSERVATIONS FROM TG6002 CONFIRM THE POTENTIAL OF OUR NEXT-GENERATION ONCOLYTIC VIRUSES

BT-001 is a patented VVcopTK-RR- oncolytic virus, with high antitumor potential, based on the Invir.IO™ platform. It is being co-developedwith BioInvent. By selectively targeting the tumor microenvironment, BT-001is expected to elicit a much stronger and more effective antitumoral response. In addition, delivering the anti- CTLA4 antibody directly to the tumor microenvironment aims to induce local Treg depletion and strong therapeutic activity. As a consequence, by reducing systemic exposure, the safety and tolerability profile of the anti-CTLA4antibody should be greatly improved. Promising preclinical results for BT-001were presented at the AACR and SITC annual congresses (June and Nov. 2020). A Phase I/IIa trial targeting solid tumors has started in

France and Belgium at the beginning of 2021.

Initial data from the Phase I trial of TG6002 confirm the good tolerability of TG6002 and demonstrate that this Vaccinia Virus, which is the same viral backbone on which the Invir.IO™ platform is based, can reach the tumor, replicate within these cancer cells and induce the production of 5-FUwhen administered intravenously.

These data will be detailed at the upcoming meeting of the AACR (April 2021).

By developing the administration of TG6002 via the intravenous and intrahepatic artery routes, Transgene aims to enlarge the number of solid tumors that could be addressed by an oncolytic virus. This includes gastrointestinal tumors that are being investigated with TG6002. To-date, the oncolytic virus that has received regulatory approval has to be given via intra-tumoral administration, restricting its use to easily accessible tumors.

Our collaboration with AstraZeneca continues to develop new innovative oncolytic viruses. AstraZeneca can exercise an option to further develop each of these novel drug candidates in the clinic.

SUMMARY OF ONGOING CLINICAL TRIALS

myvac®

TG4050

Phase I NCT03839524

TG4050

Phase I NCT04183166

Targets: tumor neoantigens

• Data demonstrating the high accuracy of AI-based neoantigen prediction technology

used to design TG4050 were presented at AACR 2020 Ovarian cancer - after surgery and first-linechemotherapy

• Trial ongoing in the United States and in France
• First patient treated in 2020 - patient enrollment progressing in line with forecast
   First data expected in 4Q 2021

HPV-negative head and neck cancer - after surgery and adjuvant therapy

• Trial ongoing in the United Kingdom and in France
• First patient treated in Jan. 2021 - patient enrollment progressing in line with forecast
   First data expected in 4Q 2021

TG4001	Targets: HPV16 E6 and E7 oncoproteins
+ avelumab	Recurrent/metastatic anogenital HPV-positive - 1st and 2nd line
Phase II	✓ Continued clinical collaboration with Merck KGaA and Pfizer, for the supply of avelumab
NCT03260023	✓ Promising Phase Ib/II results presented at SITC and ESMO IO 2020

• A randomized Phase II trial comparing the efficacy of TG4001 + avelumab vs avelumab monotherapy has received U.S. FDA clearance. In Europe, the amended

protocol has been submitted to French and Spanish health authorities

• Patient enrollment in the randomized trial expected to start in 2Q 2021
• First data from the randomized trial are expected around the end of 2022. This timeline is based on patient enrollment starting in 2Q 2021 and there being no major impact on recruitment from the Covid-19 pandemic.

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Invir.IO™

BT-001

Phase I/IIa

TG6002

Phase I/IIa NCT03724071

TG6002

Phase I/IIa NCT04194034

Payload: anti-CTLA4 antibody and GM-CSF cytokine

Solid tumors

• Co-developmentwith BioInvent
• Presentation of very encouraging preclinical results at AACR and SITC 2020
• Trial authorized. Phase I ongoing in France and Belgium
• First patient enrolled in February 2021
• First Phase I data expected in 1H 2022

Payload: FCU1 for the local production of a 5-FU chemotherapy

Gastro-intestinal cancer (colorectal cancer for Phase II) - Intravenous (IV) administration

• Multicenter trial ongoing in Belgium, France and Spain
• First findings confirm that 5-FU is produced in the tumor (Sept. 2020)  Phase I part ongoing
   A poster on the first Phase I observations has been accepted at AACR 2021

Colorectal cancer with liver metastasis - Intrahepatic artery (IHA) administration

• Multicenter trial ongoing in the United Kingdom
• First patient treated in February 2020; enrollment resumed in September 2020 after

pausing due to Covid-19

• First observations expected in 3Q 2021

KEY FINANCIALS FOR 2020

• Operating income of €9.9 million in 2020, compared to €13.7 million in 2019.
  R&D services for third parties amounted to €3.0 million in 2020 (€6.7 million in 2019), mainly due to the collaboration with AstraZeneca, which generated €2.9 million in revenues in 2020. The research tax credit reached €6.3 million in 2020 (€6.5 million in 2019).
• Net operating expenses of €33.9 million in 2020, compared to €39.2 million in 2019.
  R&D expenses were €27.3 million in 2020 (€31.4 million in 2019) with the reduction due to lower clinical trial expenses in 2020 and to the decrease of external expenses related to the manufacturing of clinical batches.
  General and administrative expenses amounted to €6.5 million in 2020 (€7.1 million in 2019).
• Financial income of €6.8 million in 2020, compared to €6.7 million in 2019.
  The partial sale of the Tasly BioPharmaceuticals shares in July 2020 generated a net gain on asset disposal of €2.7 million. Transgene's remaining shareholding was revalued and resulted in financial income of €6.4 million in 2020. This figure corresponds to the difference between the market price and the historical price.
• Net loss of €17.2 million in 2020, compared to €18.8 million in 2019.
• Cash burn reduced to €17.0 million in 2020, versus €20.5 million in 2019 (excluding capital increase).
  The net cash inflow of €18.2 million from the sale of Tasly BioPharmaceuticals shares in July 2020 reduced net cash consumption compared to 2019. This transaction enabled the Company to reimburse in advance the €10 million bank loan from the European Investment Bank (EIB) in October 2020 (against an initial maturity scheduled for this loan of June 2021).
• Cash available at year-end2020: €26.3 million, compared to €43.3 million at the end of 2019. In addition, Transgene still has access to a credit line of €15 million and holds Tasly BioPharmaceuticals shares valued at €32.3 million at the end of December 2020.
• As a result, Transgene has a financial visibility until 2022.

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HEDI BEN BRAHIM APPOINTED CHAIRMAN AND CHIEF EXECUTIVE OFFICER

Hedi Ben Brahim was appointed as the Company's Chairman and CEO, effective January 1, 2021. He has been a member of Transgene's Board since May 2019. Hedi Ben Brahim replaces Philippe Archinard, who had led the company since 2005 and who remains a member of the Board of Transgene.

The financial statements for 2020 as well as management's discussion and analysis are attached to this press release (Appendices A and B).

The Board of Directors of Transgene met on March 10, 2021, under the chairmanship of Hedi Ben Brahim and closed the 2020 financial statements. Audit procedures have been performed by the statutory auditors and the delivery of the auditors' report is ongoing.

The Company's universal registration document, which includes the annual financial report, will be available early April 2021 on Transgene's website, www.transgene.fr.

A conference call in English is scheduled today, March 10, 2021, at 6:00 p.m. CET / 12:00 p.m. EST.

Webcast link to English language conference call: https://channel.royalcast.com/landingpage/transgene/20210310_1/

Participant telephone numbers:

France: [phone]Confirmation code: Transgene

United Kingdom: [phone]

United States: [phone]

A replay of the call will be available on the Transgene website (www.transgene.fr) following the live event.

A video conference in French is scheduled on March 11, 2021, at 10:00 a.m. CET.

Webcast link to English language conference call: https://channel.royalcast.com/landingpage/transgene/20210311_2/

Participant telephone numbers:
France: [phone]	Confirmation code: Transgene

A replay will be available on the Transgene website (www.transgene.fr) following the live event.

Contacts
Transgene:	Media:
Lucie Larguier	Citigate Dewe Rogerson
Director Corporate Communications & IR	David Dible/Sylvie Berrebi
[phone]	+ 44 (0)20 7638 9571
[e-mail]	[e-mail]

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