Fathom Therapeutics Adds Kos Biotechnology Partners to $55 Million Series A for AI Drug Design

Fathom Therapeutics, a New York-based drug design company using quantum chemistry, molecular simulation and AI, has added Kos Biotechnology Partners to its oversubscribed $55 million Series A. Kos announced the investment on Nov. 6, writing its check through Kos BioVentures, the firm's inaugural life sciences fund.

Sutter Hill Ventures led the round, with participation from Lilly Ventures and other investors. Fathom — which operated as Atommap before rebranding — first disclosed $47 million of the Series A in April, and the round has since grown to $55 million.

Inside the Microcosmos Platform

Fathom's core technology is Microcosmos, a proprietary platform that combines physics-based simulation with AI to predict how proteins move and interact with drug molecules at atomic resolution. By modeling protein dynamics, the company aims to generate the data needed to design small molecules with differentiated therapeutic effects and lower off-target risk.

The focus is on biological targets historically considered "undruggable" — proteins whose shape or behavior has made them difficult to hit with conventional small molecule approaches.

A Team With Supercomputing Roots

Fathom is led by CEO Huafeng Xu, a veteran of computational drug design, alongside co-founders Yujie Wu, chief technology officer, and Jesús Izaguirre, chief computational scientist. The team includes scientists behind the Anton supercomputer and widely used methods for predicting protein-drug interactions.

The company recently appointed Bret Williams as chief scientific officer. Williams brings more than 20 years of drug discovery experience, most recently as senior vice president and head of research at Magnet Biomedicine, with earlier leadership roles at Relay Therapeutics and Sanofi. Fathom has offices in New York and Boston.

Who Is Kos Biotechnology Partners?

Kos is a global life sciences investment firm based in New York and Athens, Greece, that aims to bridge the U.S. and European biopharma ecosystems. Founded by managing partners Simos Simeonidis and Alex Tzoukas, the firm manages $125 million and invests across all development stages in therapeutics, biodefense and tech-enabled pharma services.

Tzoukas said Fathom has "assembled a world-class team with deep expertise in molecular simulation and drug discovery," while Simeonidis called the platform's potential to change "how we discover medicines" significant.

"We welcome Simos, Alex and the deeply experienced Kos team to our syndicate of investors," Xu said.

What Comes Next

Fathom plans to use the capital to scale the Microcosmos platform, advance its internal pipeline and expand strategic partnerships.

The round adds to a crowded but well-funded field of AI drug discovery startups. Fathom's bet is that pairing AI with rigorous physics-based simulation — rather than relying on pattern-matching alone — can unlock targets that have resisted traditional approaches. With a pharma-affiliated investor in Lilly Ventures and now a transatlantic specialist in Kos, the company is building a syndicate positioned to support it as programs move toward the clinic.

Source

PR Newswire — "Kos Biotechnology Partners Announces Investment in Fathom Therapeutics to Advance Novel, AI-Driven Drug Discovery Platform"