The most expensive moment in a CAR-T program is the first severe adverse event the team has not pre-defined. Grading scales, intervention thresholds, and the criteria for escalation should be settled — and mapped to the data elements your systems capture — before enrollment opens, not improvised after a patient is in front of you.

Two toxicities that behave differently

Cytokine release syndrome (CRS) is a systemic inflammatory response that can range from manageable fever to multi-organ involvement. ICANS — immune effector cell-associated neurotoxicity — follows its own trajectory and grading logic, and can occur with or without CRS. Treating them as one phenomenon, or grading them with instruments built for chemotherapy toxicity, introduces error precisely where precision matters.

What to settle before dosing

• Consensus grading criteria, written into the protocol and the safety plan, with the data fields that evidence each grade.
• A named physician reviewer and a defined adjudication pathway — including after-hours coverage matched to how fast these events move.
• Pre-agreed intervention and reporting thresholds, so the question at the moment of the event is execution, not definition.

None of this is exotic for a team that has done it before. The risk concentrates in programs deploying advanced therapeutics for the first time with a safety apparatus designed for something slower.