Discovery linking gut bacteria to cancer treatment wins the Bial Award in Biomedicine 2025

A team led by researchers Laurence Zitvogel and Guido Kroemer, internationally renowned French academics, has won the fourth edition of the Bial Award in Biomedicine with a study on the role of the gut microbiome in the efficacy of cancer immunotherapy. This discovery brings a groundbreaking shift in our understanding of the mechanisms of resistance to cancer therapy (watch video of the winning work here).

The prize was awarded at a ceremony held on 24 February at the Abel Salazar building of the University of Porto, attended by Gonçalo Matias, Minister in the Cabinet of the Prime Minister and of State Reform, on behalf of the Prime Minister, the Rector of the University of Porto, António Sousa Pereira, the Chairman of the Bial Foundation, Luís Portela, the President of the Jury, Ralph Adolphs, and awardees Laurence Zitvogel, Guido Kroemer, Bertrand Routy, Emmanuelle Le‑Chatelier and Lisa Derosa.

The study “Gut microbiome influences efficacy of PD‑1–based immunotherapy against epithelial tumors”, published in Science in January 2018, reveals that a healthy gut microbiota can enhance the efficacy of immunotherapy used to treat cancer, while antibiotics may impair its effect by reducing intestinal microbiota diversity. The awarded work represents a remarkable scientific breakthrough, opening new therapeutic avenues and exemplifying the transformative potential of excellence in biomedical research.

The Bial Award in Biomedicine 2025, worth €350,000, distinguishes the work of Laurence Zitvogel (Gustave Roussy and Paris‑Saclay University), Guido Kroemer (Gustave Roussy and Paris Cité University) and 46 co‑authors affiliated with institutions in France, Sweden, and the United States.

The awarded research documents one of the most significant recent advances in the treatment of several types of cancer, as it establishes that the gut microbiome - the collection of bacteria residing in the human intestine - plays a decisive role in the effectiveness of immunotherapy.

Immunotherapy has revolutionised oncology by enabling the immune system to recognise tumour cells once again and attack them, saving the lives of many patients who previously had no effective therapeutic alternatives. However, more than half of patients develop resistance to these therapies, leading to disease recurrence for reasons that had until now been poorly understood. The distinguished study demonstrates that the gut microbiome plays a central role in this resistance and that its modulation can significantly improve treatment response and patient survival.

The authors show that the use of antibiotics can negatively impact the effectiveness of immunotherapy by reducing gut microbiota diversity. Analysis of cancer patients revealed that greater bacterial diversity is associated with better clinical outcomes. The study also identified specific gut bacterial species consistently associated with more favourable treatment responses, establishing causal links through experiments in animal models.

The study was published in Science in January 2018 and has already accumulated more than 5,800 scientific citations, reflecting its profound and lasting impact on biomedical research.

According to the Jury of the Bial Award in Biomedicine, this work represents a true scientific tour de force, integrating basic research data, animal model studies, and clinical observations in patients, highlighting the deep connections between the immune system, the human body, and the microorganisms that inhabit it. Beyond its conceptual value, the study suggests concrete and immediately applicable modifications to clinical practice, notably judicious use of antibiotic consumption in cancer patients undergoing immunotherapy.

As emphasised by Ralph Adolphs, president of the Jury, “by uncovering the central role of the gut microbiome in the response to immunotherapy, this study redefines how we understand the mechanisms underlying resistance to cancer treatment. It is a remarkable scientific breakthrough that opens new therapeutic avenues and exemplifies the transformative power of excellence in biomedical research”.

The 2025 edition of the Bial Award in Biomedicine received 58 nominated works from 18 countries, covering areas such as cancer, infectious diseases, and neurodegenerative disorders. Previous editions have distinguished research that later went on to receive some of the most prestigious international scientific prizes

The next edition of the Bial Award in Biomedicine, promoted by the Bial Foundation, will take place in 2027.

Authors of the award-winning work and their institutions at the time of publication of the research report:

Bertrand Routy,^1,2,3 Emmanuelle Le Chatelier,⁴ Lisa Derosa,^1,2,3 Connie P. M. Duong,^1,2,5 Maryam Tidjani Alou,^1,2,3 Romain Daillère,^1,2,3 Aurélie Fluckiger,^1,2,5 Meriem Messaoudene,^1,2 Conrad Rauber,^1,2,3 Maria P. Roberti,^1,2,5 Marine Fidelle,^1,3,5 Caroline Flament,^1,2,5 Vichnou Poirier-Colame,^1,2,5 Paule Opolon,⁶ Christophe Klein,⁷ Kristina Iribarren,^8,9,10,11,12 Laura Mondragón,^8,9,10,11,12 Nicolas Jacquelot,^1,2,3 Bo Qu,^1,2,3 Gladys Ferrere,^1,2,3 Céline Clémenson,^1,13 Laura Mezquita,^1,14 Jordi Remon Masip,^1,14 Charles Naltet,¹⁵ Solenn Brosseau,¹⁵ Coureche Kaderbhai,¹⁶ Corentin Richard,¹⁶ Hira Rizvi,¹⁷ Florence Levenez,⁴ Nathalie Galleron,⁴ Benoit Quinquis,⁴ Nicolas Pons,⁴ Bernhard Ryffel,¹⁸ Véronique Minard-Colin,^1,19 Patrick Gonin,^1,20 Jean-Charles Soria,^1,14 Eric Deutsch,^1,13 Yohann Loriot,^1,3,14 François Ghiringhelli,¹⁶ Gérard Zalcman,¹⁵ François Goldwasser,^9,21,22 Bernard Escudier,^1,14,23 Matthew D. Hellmann,^24,25 Alexander Eggermont,^1,2,14 Didier Raoult,²⁶ Laurence Albiges,^1,3,14 Guido Kroemer,^{8,9,10,11,12,27,28*} Laurence Zitvogel^1,2,3,5*

¹Gustave Roussy Cancer Campus (GRCC), Villejuif, France.
²Institut National de la Santé et de la Recherche Medicale (INSERM) U1015 and Equipe Labellisée–Ligue Nationale contre le Cancer, Villejuif, France.
³Univ. Paris-Sud, Université Paris-Saclay, Gustave Roussy, Villejuif, France.
⁴MGP MetaGénoPolis, INRA, Université Paris-Saclay, Jouy-en-Josas, France.
⁵Center of Clinical Investigations in Biotherapies of Cancer (CICBT) 1428, Villejuif, France.
⁶Gustave Roussy, Laboratoire de Pathologie Expérimentale, 94800 Villejuif, France.
⁷Centre de Recherche des Cordeliers, INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMRS 1138, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Paris, France.
⁸Metabolomics and Cell Biology Platforms, GRCC, Villejuif, France.
⁹Paris Descartes University, Sorbonne Paris Cité, Paris, France.
¹⁰Equipe 11 Labellisée–Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France.
¹¹INSERM U1138, Paris, France.
¹²Université Pierre et Marie Curie, Paris, France.
¹³Department of Radiation Oncology, INSERM U1030, and Molecular Radiotherapy, Gustave Roussy, Université Paris-Saclay, F-94805 Villejuif, France.
¹⁴Department of Medical Oncology, Gustave Roussy, Villejuif, France.
¹⁵Thoracic Oncology Department–CIC1425/CLIP2 Paris-Nord, Hospital Bichat-Claude Bernard, AP-HP, Université Paris-Diderot, Paris, France.
¹⁶Department of Medical Oncology, Center GF Leclerc, Dijon, France.
¹⁷Druckenmiller Center for Lung Cancer Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA. ¹⁸Molecular Immunology and Embryology, UMR 7355, CNRS, University of Orleans, Orléans, France.
¹⁹Department of Pediatric Oncology, GRCC, Villejuif, France.
²⁰Preclinical Research Platform, GRCC, Villejuif, France.
²¹Department of Medical Oncology, Cochin Hospital, Assistance Publique–Hôpitaux de Paris, Paris, France.
²²Immunomodulatory Therapies Multidisciplinary Study Group (CERTIM), Paris, France.
²³INSERM U981, GRCC, Villejuif, France.
²⁴Department of Medicine, Thoracic Oncology Service, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
²⁵Department of Medicine, Weill Cornell Medical College, New York, NY, USA.
²⁶URMITE, Aix Marseille Université, UM63, CNRS 7278, IRD 198, INSERM 1095, IHU–Méditerranée Infection, 13005 Marseille, France.
²⁷Pôle de Biologie, Hôpital Européen Georges Pompidou, Assistance Publique–Hôpitaux de Paris, Paris, France.
²⁸Department of Women’s and Children’s Health, Karolinska University Hospital, 17176 Stockholm, Sweden.
*Corresponding author.