Prognostic value of positron emission tomography-derived metabolic tumor volume for the efficacy of anti-CD19 CAR T-cell therapy in patients with relapsed/refractory non-Hodgkin lymphomas

Objective. To evaluate the impact of tumor burden, as measured by whole-body metabolic tumor volume (MTV) from 18-F-fluorodeoxyglucose PET-CT imaging, on treatment outcomes in patients with relapsed/refractory non-Hodgkin lymphomas (NHL) treated with locally produced CAR T-cell therapy. Material and methods. Metabolic volume was retrospectively investigated in 20 patients with NHL who underwent baseline pre-treatment PET-CT and received CAR T-cell therapy at N.N. Alexandrov National Cancer Center of Belarus. Results. Semi-automatically segmented (SUV>4) MTV and weight-standardized MTV (sMTV) were calculated. The median MTV and sMTV were 99.4 mL and 1.6 mL/kg, respectively. Receiver operating characteristic analysis showed AUC for MTV 0.875 and for sMTV 0.901. Using a receiver operating characteristic curve-based sMTV cutoff of 4 mL/kg, 1-year progression-free survival (PFS) was 17.9% for high MTV versus 90.9% for low sMTV (p = 0.01), and 1-year overall survival (OS) was 17.9% and 100%, respectively (p <0.01). No statistically significant association between MTV and toxicity severity was found. Conclusion. Our data provide additional evidence for the predictive power of MTV on efficacy outcomes in patients with R/R NHL treated with CAR T-cell therapy. Specifically, sMTV discriminates high versus low tumor burden and predicts PFS and OS outcomes. Furthermore, these data indicate that efforts to reduce pretreatment tumor burden may improve longitudinal clinical outcomes.