Xaira Therapeutics

Xaira Therapeutics is a Seattle-based AI drug discovery company launched in 2024 with $1 billion in Series A funding from ARCH Venture Partners and Foresite Labs — the largest single venture raise for an AI biotech startup — giving the company a $4 billion valuation at inception. Xaira was co-founded by David Baker, the 2024 Nobel Prize in Chemistry laureate for his pioneering work in protein design and directed evolution, alongside CEO Marc Tessier-Lavigne, former President of Stanford University and neuroscientist.

The company's defining characteristic is an AI-first architecture: the AI platform is built before any drug pipeline, so every therapeutic candidate is generated by the model rather than the model being trained on existing chemistry. Xaira's flagship AI model, X-Cell, is described as the largest cell perturbation model built to date — trained to predict gene function from genetic perturbation experiments, enabling the company to identify novel disease targets based on cellular biology at a scale no human research team could achieve manually.

The company focuses on small molecule and biologic therapeutics across multiple disease areas including oncology, immunology, and neurology, with pipeline assets expected to enter IND-enabling studies from 2026. Xaira represents the 'AI-first' wave of biotech — distinct from earlier AI drug discovery companies that applied AI to existing biology pipelines — because both the disease target identification and the molecule design originate from AI foundation models built specifically for biological systems.