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Chai Discovery's Bitter Lesson: Drug Design Is Another Scaling Problem

August 4, 2026

AI Summary

5 min read

In 2020, AlphaFold2 proved that deep learning could solve protein folding. But for Josh and Matt, co-founders of Chai Discovery, that breakthrough was just the beginning of a harder question: if you can predict what a protein looks like, can you design one from scratch that does exactly what you want? Their answer is a company built on the "bitter lesson" — the idea that general scaling of data, compute, and model size beats bespoke biological tricks. And it is working faster than they expected.

The Bitter Lesson Applied to Biology

Chai Discovery’s core philosophy is borrowed directly from the playbook that worked for large language models. "We're a very bitter lesson pill company," Josh says. "We really believe in scaling data, scaling models, scaling compute." This means resisting the temptation to add specialized submodules for every new biological problem. Their first model, Chai 1, had 23 distinct submodules — and that was already too many. "When you're trying to iterate on something like that, it gets really hard," Matt explains. "You need to understand each submodule independently, all their behaviors and dynamics. That doesn't actually scale that well." The goal is to identify the few core scaling directions that matter and let the model learn the rest from data, the same way GPT learned to speak multiple languages without separate modules for each one.

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What you'll learn

  • 1 (00:00) **Bitter Lesson Philosophy & Simplicity** - The guiding principle of Chai Discovery: simplicity over complexity in model design.
  • 2 (00:53) **The Big Idea: From Drug Discovery to Drug Design** - Chai's mission is to turn drug discovery into an engineering discipline.
  • 3 (02:22) **The Shifting Boundary: Engineering vs. Real-World Testing** - How the proportion of the drug development process that can be engineered is increasing.
  • 4 (03:25) **The Evolution of State-of-the-Art (2018-2024)** - A timeline of major breakthroughs leading to the current capabilities.
  • 5 (06:09) **The 2024 Tipping Point: Antibody Design** - Why the founders believed the time was right to start the company.
  • 6 (07:03) **The "Bitter Lesson" View of Biology** - Treating biology not as a bespoke problem but as another scaling problem.
  • 7 (09:51) **Why Diffusion Models Work for Biology** - An intuitive explanation of the core generative technology.

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Show Notes

Most people treat biology as a bespoke, messy science. Josh Meier and Matt McPartlon, co-founders of Chai Discovery, treat it as an engineering problem. They make the case that drug design obeys the bitter lesson: scale data, models, and compute, and the model can learn what a hand-built pipeline simply couldn't capture. The results are concrete: Chai-2 pushed de novo antibody design from a sub 0.1% hit rate to 16%, turning a needle-in-a-haystack search into something more like designing a key to fit a lock. Josh argues, counterintuitively, that biology is more verifiable than code, and explains why the goal should be more lab experiments, not fewer. Their bet: a design suite that collapses drug discovery from nine months to nine days, and arms the pharma industry rather than competing with it.


Hosted by Pat Grady and Sonali Singh, Sequoia Capital


00:00 Introduction 01:52 From Discovery to Design 03:25 Protein AI Breakthroughs Timeline 06:04 Why Start in 2024 10:13 Diffusion Models Intuition 11:41 Building the Avengers Team 15:22 Hit Rates and Scaling Laws 25:01 Molecular CAD Vision 25:24 Faster Design Loops 26:32 Future Drug Discovery 28:37 Platform Business Model 31:14 Partnering Reality Check 33:44 Data Flywheel Explained 37:16 Staying Ahead at Scale 39:44 Culture and What's Next


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