A new report on T-cell engagers (TCEs) focuses on the core engineering dilemma: maintaining strong antitumor activity while keeping immune activation within tolerable safety margins. The piece highlights that TCE performance in solid tumors can be limited by off-tumor immune engagement and excessive activation that translates into toxicity risk. It outlines how current design strategies attempt to tune activity and safety, reflecting the platform’s demonstrated clinical responses across multiple tumor types. The emphasis on balancing the therapeutic index suggests ongoing iteration is needed for solid-tumor deployments. For developers evaluating pipeline risk, the report provides a checklist-like view of what system design choices are now scrutinized in TCE programs.