Exin Therapeutics: Claude Sonnet 5 agent picks a gene therapy and drives a live mouse brain injection; Opus 5.5 declined
Exin Therapeutics co-founder and CEO Gabriel Ocana-Santero said on X on Oct 28 that an AI agent chose one of 19 gene therapy vectors, picked the brain region, derived coordinates from three papers and drove a stereotaxic rig to inject 250 nanolitres into an epilepsy-model mouse. WIRED reports Claude Opus 5.5 refused and Sonnet 5 did the run; a vet gated every irreversible step, and the work is not peer-reviewed.

Key Takeaways
- The agent chose the drug from 19 vectors, picked the brain region and derived coordinates from 3 papers (per the CEO)
- It injected 250 nL while watching for bleeding via the rig camera; The Decoder reports 32 observations during the procedure
- Per WIRED, Claude Opus 5.5 refused to inject, so the team used Sonnet 5; the run took just over 1 hour vs about 45 minutes normally
- After a coordinate fault the agent refused to bypass its safety limits and the team had to fix the code separately; a vet still did the craniotomy
- The original post drew 9,426 likes and 1.6M+ views; seizure outcomes are pending and nothing is peer-reviewed

