This Startup Wants To Catch Cancer Before It Spreads

April 6, 2026

AI Summary

5 min read

🎙️ The Voices & The Context

The Format: This is a narrative-driven interview/podcast episode. The host (YC's Dalton Caldwell) interviews the two co-founders of Billion to One, Ozan and David, in their lab. It's structured as a "story of the company" with behind-the-scenes lab tour elements.
The Key Players:
- Ozan & David: Co-founders of Billion to One. They met as undergrads, did separate PhDs (Stanford and Rice), and started the company with a half lab bench and $300,000. They're now running a $4 billion public company.
- The Host: Dalton Caldwell (YC partner). He provides the narrative framing and asks the questions.
The Vibe: Inspiring, Technical, and Triumphant. It's an underdog story about two PhD students who solved a seemingly impossible biology problem. The tone is excited and proud, with moments of genuine tension (the "one user" crisis) and awe (the lab tour).

🗝️ Key Themes & Topics

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What you'll learn

1 (00:00) **🎙️ Introduction: Ozan and David (Co-founders of Billion to One)**
2 (01:44) **The Core Technology: Cell-Free DNA Detection**
3 (05:24) **Early Company History: From PhD Idea to First Test**
4 (08:15) **The Sales Breakthrough: Convincing the First Users**
5 (09:49) **Lab Tour: Scaling the Process with AI**
6 (12:56) **Expanding to Cancer: The Step-by-Step Plan**
7 (14:11) **Patient Impact: A Cancer Story**

+ Full timestamped outline available in the app

Show Notes

1 in 11 babies born in America this year will be screened by a genetic test that didn't exist a decade ago.Biotech startup BillionToOne turned a simple but radical idea—detecting rare fragments of fetal DNA in a mother's blood—into one of the most widely used prenatal tests in the U.S. And they're not stopping there. The same approach could unlock something even bigger: early-stage cancer detection from a blood test, a breakthrough that could one day save millions of lives.In this episode of Hard Tech, YC's Jared Friedman sits down with David Tsao and Oguzhan Atay to hear how they went from half a lab bench to a $4B biotech company—and why they believe this is just the beginning of what their technology can do.