Platelet and Fibrinogen Dynamics After CAR ‐T Cell Therapy in Relapsed/Refractory B‐Cell Lymphoma May Predict ICANS Onset

CAR‐T cell therapy is efficient in relapsed/refractory B‐cell lymphoma; yet, cytokine release syndrome (CRS) and immune effector cell‐associated neurotoxicity syndrome (ICANS) remain major and potentially life‐threatening complications, which makes their prediction and prevention crucial. This international, retrospective study analyzed the predictive value of coagulation parameter dynamics for ICANS and CRS development in 265 B‐cell lymphoma patients at two tertiary‐care centers. Platelet counts, fibrinogen, PT, PTT, international normalized ratio, and D‐dimer, were recorded daily from pre‐lymphodepletion through 2 weeks post‐infusion. ICANS occurred in 34% of patients, with high‐grade events documented in 13%. Patients with ICANS had significantly lower median platelet (67 vs. 123 × 10 3 /μL) and fibrinogen (263 vs. 379 mg/dL) levels than those without ICANS. During high‐grade ICANS days, fibrinogen and platelet levels were significantly reduced ( p = 0.003 and p = 1.6 × 10 −14 , respectively). In > 75% of high‐grade ICANS cases, 1 day before its onset, platelet counts were < 100 × 10 9 /L (median decrease: 11.6% versus 1.6% on other days; p = 0.001). Conversely, on the day preceding ICANS onset, higher fibrinogen concentrations were observed, with median values of 448 mg/dL in the ICANS group versus 376 mg/dL in the non‐ICANS group ( p = 0.03). These findings suggest that platelet and fibrinogen dynamics could be early indicators of ICANS development in lymphoma patients.