PRESS RELEASE


Transgene and BioInvent’s Armed Oncolytic Virus BT-001
Shows Positive Local, Abscopal, and Sustained
Antitumoral Activity in Advanced Refractory Tumors


BT-001 in combination with pembrolizumab is well tolerated and shows sustained
antitumoral activity in both injected and non-injected lesions

Data support further development of BT-001 in solid tumors to improve response
to cancer immunotherapy



Strasbourg, France, and Lund, Sweden, October 20, 2025, 08:30 a.m. CEST – Transgene (Euronext Paris:
TNG), a biotech company that designs and develops virus-based immunotherapies for the treatment of
cancer, and BioInvent International AB (“BioInvent”) (Nasdaq Stockholm: BINV), a biotech company
focused on the discovery and development of novel and first-in-class antibodies for cancer
immunotherapy, jointly presented a poster at the 2025 European Society for Medical Oncology (ESMO)
Annual Meeting on updated clinical results and positive antitumoral activity of BT-001 in patients with
advanced refractory tumors.

The data show that intra-tumoral (IT) BT-001 injection in combination with MSD’s (Merck & Co., Inc.,
Rahway, NJ, USA) intravenous (IV) anti-PD-1 therapy KEYTRUDA® (pembrolizumab*), was well tolerated
and showed positive local, abscopal and sustained antitumoral activity in injected and non-injected
lesions.

Translational analyses reveal increased T cell chemoattractants in the blood and infiltration of activated
CD8+ T cells and macrophages in tumors after treatment with BT-001 in combination with
pembrolizumab. Significant tumor shrinkage (≥30% decrease in longest diameter) was observed in five of
16 injected lesions (in three patients with melanoma and one patient with sarcoma). Four patients had
tumor shrinkage of non-injected lesions.

Long-lasting partial responses (PRs) were observed in a patient with melanoma resistant to anti-PD-1/anti-
CTLA-4 combination therapy and in a heavily pre-treated, PD-L1 negative leiomyosarcoma patient.

These immune-mediated tumor shrinkages are consistent with the mechanistic hypothesis that BT-001,
in combination with pembrolizumab, turns “cold” tumors into immunologically active ones. The overall
data support further development of BT-001 across a range of solid tumors to improve responses to cancer
immunotherapies.




*KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.



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Prof. Celeste Lebbé, Dermatologist and Venereologist, Head of Dermatology Department at Hospital Saint-
Louis, Paris, commented: “Many cancer patients fail to respond to existing treatments, emphasizing the urgent
need for new approaches. BT-001 represents a promising new class of immunotherapy, capable of inducing a
potent local immune response through the expression of GM-CSF and an anti-CTLA-4 antibody. These clinical
data provide compelling proof of concept, highlighting the relevance of this oncolytic virus in transforming cold
tumors into immunologically active ones. Whether administered alone or in combination with pembrolizumab,
BT-001 offers the potential to expand treatment options with a favorable safety profile across multiple tumor
types.”

Dr. Alessandro Riva, Chairman and CEO of Transgene, said: “We are pleased to jointly present these
clinical data on BT-001 at ESMO 2025, demonstrating encouraging antitumor activity in patients with solid,
refractory solid tumors. These updated results confirm BT-001’s mechanism of action as a single agent
administered via intra-tumoral injection and show early signs of clinical benefit, including lesion shrinkage
and stable disease. With a favorable safety profile - both alone and in combination with pembrolizumab -
BT-001 could represent an effective option to enhance responses to immune checkpoint inhibitors (ICI) in
patients with limited treatment alternatives. Together with our partner BioInvent, we will continue to
explore its safety and efficacy and share further data as it becomes available.”

Andres McAllister, MD, PhD, Chief Medical Officer at BioInvent, added: “By combining BT-001 with
pembrolizumab, we are building upon the promising data generated by BT-001 as a single agent. Targeting
the PD-1/PD-L1 pathway in addition to BT-001’s mechanism of action is expected to further stimulate and
restore the patient’s immune system, which should result in improved antitumoral activity and patient
outcome. We are pleased to pursue clinical development opportunities with clinicians and further
demonstrate the potential of this novel oncolytic virus.”

Transgene and BioInvent are co-developing BT-001, an oncolytic virus developed using Transgene’s
Invir.IO® platform armed to express GM-CSF and BioInvent’s full-length anti-CTLA-4 monoclonal antibody,
to elicit a strong and effective anti-tumoral response in solid tumors.

The poster titled: “Updated clinical results of BT-001, an oncolytic virus expressing an anti-CTLA4 mAb,
administered in combination with pembrolizumab in patients with advanced solid tumors.”, can be
accessed at the websites for the ESMO conference, Transgene and BioInvent.


***


Contacts
Transgene:
Media: Investors & Analysts:
Caroline Tosch Lucie Larguier
Corporate and Scientific Communications Manager Chief Financial Officer (CFO)
+33 (0)3 68 33 27 38 Nadege Bartoli
communication@transgene.fr Investor Relations Analyst
and Financial Communications Officer
MEDiSTRAVA +33 (0)3 88 27 91 00/03
Frazer Hall/Sylvie Berrebi investorrelations@transgene.fr
+ 44 (0)203 928 6900
transgene@medistrava.com

BioInvent
Cecilia Hofvander
VP Investor Relations
+46 (0)46,286 85 50
cecilia.hofvander@bioinvent.com



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About Transgene
Transgene (Euronext: TNG) is a biotechnology company focused on designing and developing targeted immunotherapies for the
treatment of cancer. The Company’s clinical-stage programs consist of a portfolio of viral vector-based immunotherapeutics.
TG4050, the first individualized therapeutic vaccine based on the myvac® platform is the Company’s lead asset, with demonstrated
proof of principle in patients in the adjuvant treatment of head and neck cancers. The Company has other viral vector-based
assets, including BT-001, an oncolytic virus based on the Invir. IO® viral backbone, which is in clinical development. The Company
also conducts innovative discovery and preclinical work, aimed at developing novel viral vector-based modalities.
With Transgene’s myvac® platform, therapeutic vaccination enters the field of precision medicine with a novel immunotherapy
that is fully tailored to each individual. The myvac® approach allows the generation of a virus-based immunotherapy that encodes
patient-specific mutations identified and selected by Artificial Intelligence capabilities provided by its partner NEC.
With its proprietary platform Invir.IO®, Transgene is building on its viral vector engineering expertise to design a new generation
of multifunctional oncolytic viruses.
Additional information about Transgene is available at: www.transgene.com
Follow us on social media: X (formerly Twitter): @TransgeneSA — LinkedIn: @Transgene — Bluesky: @Transgene

About BT-001
BT-001 is an oncolytic virus, from Transgene’s invir.IO® platform, with enhanced replication selectivity in tumor cells and
recombinantly armed to express an anti-CTLA4 antibody generated by BioInvent’s proprietary n-CoDeR®/F.I.R.S.T™ platforms, and
the human GM-CSF cytokine. By selectively targeting the tumor microenvironment, BT-001 is designed to induce a strong and
effective anti-tumor response and by limiting systemic exposure, this approach aims to significantly improve the safety and
tolerability profile of the human anti-CTLA-4 antibody. The ongoing Phase I/IIa trial (NCT04725331) is a multi-center, open-label
study, and aims to evaluate safety and antitumor activity of intratumoral BT-001 alone and in combination with pembrolizumab
in patients with advanced solid tumors.

About BioInvent
BioInvent International AB (Nasdaq Stockholm: BINV) is a clinical-stage biotech company that discovers and develops novel and
first-in-class immuno-modulatory antibodies for cancer therapy, with several drug candidates in ongoing clinical programs in Phase
1/2 studies for the treatment of hematological cancer and solid tumors, respectively. The Company’s validated, proprietary
F.I.R.S.T.™ technology platform identifies both targets and the antibodies that bind to them, generating many promising new drug
candidates to fuel the Company’s own clinical development pipeline and providing licensing and partnering opportunities.
The Company generates revenues from research collaborations and license agreements with multiple top-tier pharmaceutical
companies, as well as from producing antibodies for third parties in the Company’s fully integrated manufacturing unit. More
information is available at www.bioinvent.com

Disclaimer Transgene
This press release contains forward-looking statements, which are subject to numerous risks and uncertainties, which could cause
actual results to differ materially from those anticipated. The occurrence of any of these risks could have a significant negative
outcome for the Company’s activities, perspectives, financial situation, results, regulatory authorities’ agreement with
development phases, and development. The Company’s ability to commercialize its products depends on but is not limited to the
following factors: positive pre-clinical data may not be predictive of human clinical results, the success of clinical studies, the ability
to obtain financing and/or partnerships for product manufacturing, development and commercialization, and marketing approval
by government regulatory authorities. For a discussion of risks and uncertainties which could cause the Company’s actual results,
financial condition, performance or achievements to differ from those contained in the forward-looking statements, please refer
to the Risk Factors (“Facteurs de Risque”) section of the Universal Registration Document, available on the AMF website
(http://www.amf-france.org) or on Transgene’s website (www.transgene.fr). Forward-looking statements speak only as of the
date on which they are made, and Transgene undertakes no obligation to update these forward-looking statements, even if new
information becomes available in the future.

Disclaimer BioInvent
The press release contains statements about the future, consisting of subjective assumptions and forecasts for future scenarios.
Predictions for the future only apply as the date they are made and are, by their very nature, in the same way as research and
development work in the biotech segment, associated with risk and uncertainty. With this in mind, the actual outcome may deviate
significantly from the scenarios described in this press release.




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