Milestones
- Disease chosen; development starts2024Complete.
- First person dosed2025Complete.
- Finish safety trialNowCurrent milestone.
- Phase 2 in Alzheimer's patientsNot yet reached.
Most important updates
- Dec 2025
Current obstacles
- Proving it reaches the brainShowing the drug gets into the brain and boosts cleanup there is hard without good tests.
Physics limits
- The blood-brain barrier blocks most drugsTightly sealed brain capillaries keep out roughly 98% of small-molecule drugs. A brain pill must be small and fat-soluble enough to slip through, which narrows the chemistry that can be used.
- Cleanup can't bring back lost neuronsAdult brain cells barely regenerate. Once neurons die in Alzheimer's they are gone, so boosting cell recycling can at best slow decline and has to start early.
- Recycling is a balance, not a dialCells that digest their own parts too hard lose proteins they need. The pathway is tightly regulated, so there is a limited dose range between no effect and harm.
How it works
Problem
Cleanup fails with age
Recycling slows in old brain cells, so toxic protein clumps build up.
Drug
A pill to restart it
RTR242 aims to restart autophagy, the cell's recycling system, so brain cells clear protein clumps and worn-out parts.
Trial
Safety first
The first trial checks safety and how the body handles the drug in healthy people.
Update log
Dec 2025
- Major: PressTest
About Retro Biosciences
Retro Biosciences
Cell-cleanup pill, young cell transplants, AI
Bay Area company founded in 2021 by Joe Betts-LaCroix with $180M from Sam Altman, aiming to add ten healthy years to human life. It makes young replacement cells for blood and brain, and RTR242, a pill for Alzheimer's that entered trials in 2025.
- RTR242 went from choosing a disease to the first human dose in about 15 months (trial in Adelaide, Australia).
- In 2025 Retro and OpenAI reported AI-designed versions of two Yamanaka factors that worked better in lab cells.
- May 2026: first close of a new round at a $1.8B valuation, led by 4P Capital.
- Founded
- 20215 yrs
- Headquarters
- United States
- Status
- Private
- Valuation
- $1.8BprivateMay 2026
- Raised
- $180M2 rounds
- Last round
- New round (initial close)May 2026
- Coverage
- 3 programs · 5 updateslatest 1 May 2026checked 25 Sep
- Lead investors
- 4P CapitalSam Altman
- Partners
- OpenAI (opens openai.com)
- People
- Joe Betts-LaCroix (opens retro.bio)Co-founder and CEOSam Altman (opens en.wikipedia.org)Founding investor