The archive · Bio & Materials · Product decision · 2021–2025
Phagos bets AI-designed phages replace antibiotics in animals; €25M Series A
Paris biotech Phagos pairs AI with bacteriophages, bacteria-killing viruses, to fight antibiotic resistance in livestock first; €25M Series A.
Phagos
What the business is
Phagos develops AI-enhanced bacteriophage (phage) therapies — viruses that prey on specific bacteria — with an initial focus on veterinary medicine and a longer-term goal of human health.
How it started
Founded in Paris in 2021 by Alexandros Pantalis and Adèle James, Phagos bet that bacteriophages — the natural predators of bacteria — could be turned into a scalable alternative to antibiotics. The founders chose animal health first, where declining antibiotic effectiveness is an immediate production problem, with the ambition to extend phage therapy to humans later.
What happened
Phagos raised a €2.4M seed round in 2022, then spent the next three years building the platform: AI that predicts phage-bacteria interactions from complete genomes, a patent on that technology, and an authorization to market personalized phage-based veterinary medicines — described as a notable regulatory milestone. In October 2025 it closed a €25M Series A co-led by CapAgro, Hoxton Ventures, CapHorn, and Demeter, with Acurio Ventures, Citizen Capital, Entrepreneur First, Founders Capital, and Station F participating. The company had grown to about 50 employees, 90% of them in microbiology, IT, R&D, data, and AI roles.
How it ended up
Still scaling as of October 2025: the Series A funds large-scale deployment of veterinary phage therapies, the next generation of its patented AI, and international growth, before a planned push into human health.
Background
Phagos was founded in Paris in 2021 by Alexandros Pantalis and Adèle James on a specific bet: bacteriophages — viruses that kill specific bacteria — could become a practical, scalable alternative to antibiotics, and the fastest path to prove it ran through animal health, where resistance erodes the effectiveness of livestock medicine directly.
The company's platform combines microbiology with AI: it analyses complete phage and bacterial genomes to predict which phages will work, designs precise personalized treatments, and can adapt them as pathogens evolve. Phagos filed a patent on that AI and, notably, received authorization to market personalized phage-based veterinary medicines — a regulatory milestone in treating bacterial infections, according to tech.eu.
In October 2025 Phagos closed a €25M Series A co-led by CapAgro, Hoxton Ventures, CapHorn, and Demeter, with Acurio Ventures, Citizen Capital, Entrepreneur First, Founders Capital, and Station F participating — three years after a €2.4M seed. The round funds large-scale deployment of its veterinary solutions and next-generation AI, with the stated longer-term goal of extending phage therapy to human health, where antimicrobial resistance is projected to become one of the world's biggest health and economic burdens.
What has to be true
- Choosing animal health first gave Phagos a market where antibiotic resistance is an immediate, economically painful problem rather than a distant one.
- A patented AI platform turned phage therapy from a bespoke, unscaleable lab service into something that can be designed for new pathogens quickly.
- The veterinary marketing authorization was a first-mover moat that no later-round competitor could copy quickly.
- The company kept the story simple for investors: solve a concrete problem in livestock now, with the human-health market as the option value.
What can be applied
Start where pain is acute and regulation reachable: animal health gave a young biotech its first market and regulatory authorization — the moat later rounds pay for.
Aftermath
As of October 8, 2025, Phagos had just closed its €25M Series A and was preparing to scale veterinary phage-therapy deployment, advance the next generation of its patented AI, and grow internationally, with about 50 employees and a first regulatory authorization to market personalized phage-based veterinary medicines already secured. The founders stated the goal of establishing phage therapy as a global standard — animal health first, human health as the longer-term horizon.
Sources
- Phagos gets €25M boost to combat bacterial diseases
- La biotech Phagos lève 25 millions d'euros pour éradiquer les maladies bactériennes
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