Phagos: Ending Bacterial Disease with Phage Therapy

Founded in 2021, Phagos is a biotech startup developing a sustainable alternative to antibiotics through phage therapy. Co-founded by Alexandros Pantalis, an HEC Paris graduate, and Adèle James, PhD in molecular microbiology, the startup designs personalized phage-based veterinary medicines for animal farming.

Four years after its creation, Phagos has reached a major regulatory milestone, becoming the first company in the European Union authorized to commercialize tailor-made veterinary medicines based on bacteriophages. The startup can develop a treatment in just two months, and is already working with some of the world’s largest agrifood players.

Bacterial infections represent one of the most critical health challenges of our time. They are already the second leading cause of death worldwide in humans, a major cause of mortality in livestock, and generate massive economic losses across the agrifood sector.

This silent crisis is amplified by antimicrobial resistance (AMR), with resistance increasing 5 to 15% annually according to the World Health Organization. AMR already causes millions of deaths each year, and antibiotic-resistant bacteria are projected to surpass cancer in lethality while costing the global economy up to $100 trillion by 2050.

In animal farming, the situation is particularly acute: one antibiotic out of three is now ineffective, three times more than in 2000. As antibiotics lose efficacy, existing solutions are too generic and no longer sufficient to protect animal health, food systems, and, ultimately, human health.

Phagos has developed a unique phage therapy platform that combines microbiology with artificial intelligence to design personalized phage-based medicines, offering a radically different way of addressing the problem.

A bacteriophage (often shortened to phage) is a virus that infects and kills bacteria, while leaving other cells untouched. Each phage is highly specific: it targets only a few bacterial strains, making it fundamentally different from broad-spectrum antibiotics.

Phagos’ approach is based on:

• Bacteriophages, the natural predators of bacteria, as a targeted alternative to antibiotics.
• Personalized treatments, designed for a specific bacterial strains rather than a one-size-fits-all drug
• Continuously updated medicines, able to adapt as bacteria evolve
• Proprietary AI models, capable of analyzing entire phage and bacterial genomes to predict interactions and select the most effective phages

As a result, Phagos can develop a customized cure in just two months, compared to an average of 12 years and $2 billion required to bring a new antibiotic to market. The first application focuses on veterinary medicine, with the long-term ambition of extending this breakthrough to human health.

• 1st time a phage platform is validated by authorities in the EU, and actually globally.
• 2 months to develop a new tailor-made treatment compared to 12 years for a new antibiotic.
• 1 million animals treated in France in just a few months
• €25M Series A (2025), and €30M total raised
• 50+ employees and 90% with scientific backgrounds
   

Phagos emerged from the meeting of two highly complementary profiles: Alexandros Pantalis brings entrepreneurial drive, business execution, and resilience forged through multiple previous startup attempts. Adèle James contributes deep scientific expertise and a strong desire to change how science is conducted and translated into real-world impact.

Together, they built a company culture centered on scientific rigor, fast execution, and a human work culture, deliberately moving away from the competitive and siloed environments both founders had experienced in academia. The journey was marked by intense moments, from early fundraising challenges to the first clinical and field applications, where the company’s future was on the line.

What proved decisive was their ability to attract deeply committed people from the very start, despite the uncertainty, pressure, and risk inherent in building an early-stage biotech company. Looking back on this journey also shaped them with a clear personal conviction: “Trust your gut. And ‘in theory, it should work’ often works.”

With its recent €25 million Series A, Phagos has entered a new phase of growth. The company aims to accelerate the large-scale deployment of veterinary phage therapy, further develop the next generation of its patented AI technology for phage characterization, and expand internationally across Europe, Asia, and the Americas.

The long-term mission remains unchanged and ambitious: End bacterial disease.