The FDA accepted a Biologics License Application for Bristol Myers Squibb’s targeted protein degrader, formally initiating review, while separately issuing a rejection for a Disc Medicine rare disease filing. The acceptance marks progress for degrader therapeutics — an emerging modality that uses small molecules to tag disease proteins for ubiquitin–proteasome destruction — and places a spotlight on regulatory expectations for safety, biomarker strategy and manufacturing for these novel agents. The outcome will be watched as a barometer for how reviewers evaluate degrader mechanisms versus traditional inhibitors.