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Sequoia CapitalSequoia Capital

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

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.

Pat GradyhostSonali Singhhost
Aug 4, 202647mWatch on YouTube ↗

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At a glance

WHAT IT’S REALLY ABOUT

Chai Discovery argues AI drug design improves by scaling and simplicity

  1. Chai Discovery describes its mission as making drug development look more like engineering by moving from “discovery” via massive screening toward “design” where desired properties and constraints can be specified upfront and generated by models.
  2. Speakers outline recent protein-AI progress from early deep-learning distance prediction to major performance steps (including AlphaFold 2) and then to diffusion-enabled generative design that can produce structure and sequence together under constraints.
  3. They explain diffusion models as an iterative denoising process (“make it slightly better”) that made it possible to generate realistic proteins compared with earlier generative approaches they found harder to apply.
  4. Chai reports a major jump in antibody binding hit rates (from about 0.1% to about 15% with Chai2) and argues that higher hit rates strengthen feedback loops for improving additional properties.
  5. The company positions itself as an infrastructure/platform partner to pharma—prioritizing rigorous evaluation, production-ready deployment, and a data flywheel from experiments and partner usage—rather than building a full-stack clinical pipeline.

IDEAS WORTH REMEMBERING

5 ideas

Simplicity is positioned as a core scaling strategy for Chai’s modeling approach.

A speaker argues that highly modular models become hard to iterate on because researchers must understand each submodule’s behavior and dynamics; simplifying to what matters most makes it easier to find scaling directions and run an effective research loop.

Chai’s goal is to shift drug discovery toward a design-oriented, engineering-like workflow.

A speaker frames today’s paradigm as “drug discovery” (searching for needles in haystacks via massive screening) and contrasts it with “drug design,” where you specify the desired molecule up front and the model generates candidates that meet constraints; they add that lab work remains central for verification and might even increase if ROI rises.

Recent protein AI progress is presented as an evolution from folding to constrained, generative design—accelerated by diffusion models.

A speaker walks through a timeline: deep learning enabled early progress in predicting amino-acid distance patterns; performance stepped up around 2018 and again around 2020 with AlphaFold 2; later efforts moved from structure prediction to sequence design, and diffusion models enabled generating structure and sequence together with more realistic constraints (e.g., “bind here”).

Diffusion models are explained as working well because they break generation into many small correction steps.

Speakers describe diffusion as an iterative “make it slightly better” process—training on progressively noisier or “broken” proteins and repeatedly denoising—contrasting it with one-shot compression approaches like variational autoencoders that were described as harder for their setting at the time.

Improving hit rates is portrayed as the unlock that turns weak feedback into scalable iteration.

A speaker says the company focused on de novo molecule generation rather than only “make a known molecule a bit better” with lab-in-the-loop workflows; they cite improving antibody design binding success from about 0.1% to about 15% with their Chai2 model, enabling richer statistics on properties and faster iterative improvement.

WORDS WORTH SAVING

5 quotes

What we often, uh, look at this is like the lab is, is an important part to, to verify that what you're doing is correct, and actually verification's a very big theme in AI as well.

— Unattributed

When we started the company, the state-of-the-art for antibody design was about, like, a 0.1% binding rate, so one in 1,000 of the molecules you design would actually bind in the lab.

— Unattributed

We got to, uh, with our Chai2 model, about, like, a 15% success rate.

— Unattributed

One thing that I really like about Chai is like we're, we're a very Bitter Lesson-pilled company, so like we really believe in like scaling data, scaling models, scaling compute.

— Unattributed

It used to be like you either wanna be first in class or best in class.

— Unattributed

Read the available transcript
Drug discovery vs drug design paradigm shiftProtein folding competition and performance step changesDiffusion models for protein generationAntibody structure prediction and design focusHit rates, scaling laws, and simplicity in model designEvaluation/verification in wet lab and error barsPlatform partnerships with pharma vs full-stack drug pipeline approach

SPEAKERS

  • Pat Grady

    host

    Partner at Sequoia Capital and podcast host/interviewer.

  • Sonali Singh

    host

    Partner at Sequoia Capital and podcast host/interviewer.

High quality AI-generated summary created from speaker-labeled transcript.

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