Standardized FDG-PET interpretation during CAR T-cell therapy in R/R DLBCL: a DESCAR-T study

Area of Science:

• Oncology
• Immunotherapy
• Radiology

Background:

• CAR T-cell therapy has revolutionized treatment for relapsed/refractory (R/R) Diffuse Large B-cell Lymphoma (DLBCL).
• Fluorodeoxyglucose Positron Emission Tomography Computed Tomography (PET/CT) is crucial for assessing lymphoma response but lacks standardized prognostic utility in this context.

Purpose of the Study:

• To evaluate the prognostic value of baseline and early post-treatment PET/CT metrics, including Total Metabolic Tumor Volume (TMTV) and Deauville Score (DS), in R/R DLBCL patients undergoing CAR T-cell therapy.
• To establish optimal cut-offs for TMTV and determine the prognostic impact of DS at one (M1) and three (M3) months post-infusion.

Main Methods:

• Analysis of 212 R/R DLBCL patients from the French DESCAR-T registry treated with anti-CD19 CAR T-cells.
• Central review of PET/CT scans before infusion and at M1/M3, measuring TMTV and SUVmax.
• Assessment of DS and response using the 2014 Lugano classification to correlate with progression-free survival (PFS) and overall survival (OS).

Main Results:

• A baseline TMTV cut-off of 30 cm³ significantly stratified patients for PFS and OS.
• Complete metabolic response (DS 1-3) at M1 correlated with significantly better PFS and OS compared to DS 4-5, with DS 5 indicating the worst outcomes.
• Residual TMTV after treatment provided additional prognostic value in patients without complete metabolic response.

Conclusions:

• Baseline TMTV is a significant prognostic biomarker in R/R DLBCL patients treated with CAR T-cells.
• Early metabolic response assessed by Deauville Score at M1 and M3 is a strong predictor of PFS and OS.
• Residual TMTV on follow-up PET/CT offers further prognostic stratification for these patients.