# [18F]FDG-PET/CT in DLBCL-patients treated with CAR-T cell therapy: potential for defining patient prognosis

## TL;DR

This study shows that [18F]FDG-PET/CT scans can help predict outcomes for DLBCL patients undergoing CAR-T cell therapy.

## Contribution

The study identifies SUVmax > 9 as a pre-treatment predictor of poor survival and shows post-treatment PET/CT scores can signal early treatment failure.

## Key findings

- Patients with SUVmax > 9 before CAR-T therapy had significantly shorter progression-free and overall survival.
- Post-therapy Deauville score > 3 and Lugano classification of progressive disease were linked to increased risk of treatment failure.
- Early identification of non-responders could improve treatment strategies in DLBCL patients.

## Abstract

The aim of this study is to evaluate the potential of [18F]FDG-PET/CT in terms of prognostic value and treatment monitoring in relapsed / refractory diffuse large B-cell lymphoma (DLBCL)-patients treated with chimeric antigen receptor T-cell (CAR-T) therapy.

Forty-eight [18F]FDG-PET/CT scans, acquired at pre-defined time points (t0 – t2) of 18 DLBCL-patients (mean age: 60 ± 12 years) treated with CAR-T cell therapy were retrospectively enrolled. Median time of follow-up was ten months (IQR 6–16) following CAR-T cell infusion. SUVmax, sum of the product of diameters (SPD), Deauville score (DS) and Lugano classification (LC) were evaluated. Clinical parameters (age, sex) were obtained. Survival time analyses for progression-free survival (PFS) and overall survival (OS) were calculated, the latter by using the Kaplan-Meier method and Cox regression including a hazard ratio (HR). P values below 0.05 were defined as statistically significant. 95 %-confidence intervals (CI) were calculated.

Patients with a SUVmax> 9.0 at t0 (median as threshold value) had a significantly shorter PFS (p = 0.04) and OS (p < 0.01). According to LC, a progressive disease (PD) at t1 (p = 0.02) and t2 (p < 0.01) was correlated with a reduced OS. SUVmax > 9.0 at t0 (p = 0.03, HR = 7.0, CI: 1.3–40.5) and DS > 3 at t1 (p = 0.04, HR = 8.2, CI: 1.1–61.3) were associated with an increased risk of a PD.

SUVmax of [18F]FDG-PET/CT seems to be useful as a prognostic marker in DLBCL-patients undergoing CAR-T cell therapy. Furthermore, scores of clinical established Deauville classification and Lugano response criteria acquired at post-CAR-T [18F]FDG-PET/CT might be an indicator for early therapy failure.

•Pretherapeutic SUVmax > 9 may be an indicator for shorter PFS and OS in DLBCL-patients undergoing CAR-T cell therapy.•Deauville score and Lugano classification derived from post-therapeutic [18F]FDG-PET/CT could indicate early treatment failure.•Identifying non-responders ideally before CAR-T cell therapy initiation could be crucial.

Pretherapeutic SUVmax > 9 may be an indicator for shorter PFS and OS in DLBCL-patients undergoing CAR-T cell therapy.

Deauville score and Lugano classification derived from post-therapeutic [18F]FDG-PET/CT could indicate early treatment failure.

Identifying non-responders ideally before CAR-T cell therapy initiation could be crucial.