Impact of IL-6 and ferritin dynamics on clinical outcomes after anti-CD19 CAR-T cell therapy in diffuse large B-cell lymphoma patients.

BACKGROUND: Interleukin-6 (IL-6) and ferritin are routinely monitored during chimeric antigen receptor T-cell (CAR-T) therapy; however, their temporal dynamics and outcome-specific relevance remain inadequately characterized. This study aimed to evaluate the value of IL-6 and ferritin at multiple time points in patients with diffuse large B-cell lymphoma (DLBCL) receiving anti-CD19 CAR-T therapy. METHODS: A total of 54 patients (median age 49.0 years; 64.8% male) were retrospectively analyzed. Post-infusion IL-6 and ferritin levels were measured on day 1, day 7, day 14, and the peak value was defined as the highest level within the first 14 days after infusion. Survival was evaluated using Cox proportional hazards regression, while logistic regression was used for binary outcomes, with Firth penalized regression performed as a sensitivity analysis. Spearman correlation was used to characterize relationships between IL-6, ferritin, and routine laboratory parameters. RESULTS: CRS occurred in 68.5% of patients, and the objective response rate was 70.4%. IL-6 levels were significantly higher in patients with CRS at day 1 (P = 0.003) and at peak levels (P = 0.005). IL-6 on day 7 was associated with mortality (OR = 1.625, 95% CI: 1.076-2.737, P = 0.038). Ferritin was associated with CRS at all time points and showed an exploratory association with mortality, but not with treatment response. Day 7 IL-6 showed the numerically highest AUC for death status, whereas Day 14 ferritin showed the numerically highest AUC for CRS. IL-6 was negatively correlated with albumin at Day +1, Day +7, and peak, whereas ferritin was negatively correlated with RBC count at Day +1, Day +7, and peak. CONCLUSION: Serial IL-6 and ferritin measurements were associated with CRS-related inflammatory status. Day +7 IL-6 and Day +7 ferritin showed exploratory associations with mortality.