Regeneron signaled fresh regulatory and manufacturing challenges for its lymphoma bispecific antibody odronextamab after a string of prior hurdles. The company said ongoing issues complicate its path to full US approval despite prior clinical promise, underscoring persistent execution risks for complex biologics. Regeneron’s situation highlights how regulatory inspections, CMC (chemistry, manufacturing and controls) issues, and post‑marketing readiness can delay approvals even when clinical data are favorable. Clarification: Odronextamab is a CD20xCD3 bispecific antibody intended to redirect T cells to attack B‑cell lymphomas.