TNF‐α increases the risk of bleeding in patients after CAR T‐cell therapy: A bleeding model based on a real‐world study of Chinese CAR T Working Party

Abstract Chimeric antigen receptor (CAR) T‐cell therapy has shown excellent clinical efficacy in patients with hematologic malignancies. However, severe bleeding after this treatment is a life‐threatening complication for most patients. This study evaluated the risk factors associated with bleeding in CAR T treatment and developed a predictive model for this complication. Analysis performed in the First Affiliated Hospital of Suzhou University and external validation launched in Suzhou Hongci Hematology Hospital (Jiangsu, China). We conducted a real‐world study incorporating data from 400 patients with hematologic malignancies treated with CAR T between 1 November 2015 and 1 September 2019. Also, 39 patients from another hospital were selected for external validation. Patients with severe bleeding (hazard ratio [HR] 13.04, 95% confidence interval 5.82–29.18; p < 0.001) had a higher risk of death after CAR T. Stage III and IV cytokine release syndrome (CRS) (odds ratio [OR] 6.07, 95% CI 2.35–16.76; p < 0.001) and higher tumor necrosis factor‐α (TNF‐α) levels (OR 4.00, 95% CI 1.53–11.35; p < 0.001) were independent factors of bleeding in patients after CAR‐T treatment. The predictive model developed by Lasso regression, which selected factors such as CRS period, transfusion volume, platelet percentage, platelet count, thrombinogen time, interleukin 6, and TNF‐α levels, and showed Nomogram, yielded excellent agreement (C‐statistics = 0.905) with the calibration curve, which improved clinical benefit with respect to established bleeding scores such as outpatient bleeding risk index (MOBRI). External validation was performed using 39 patients from another hospital with an AUC of 0.700. Patients with severe bleeding after Car‐T therapy had increased the risk of death. A cross‐validated bleeding risk score based on CRS stages and TNF‐α level show significant prognostic value in patients undergoing CAR‐T treatment.