Post-chimeric antigen receptor T-cell fluorodeoxyglucose positron emission tomography-computed tomography findings in Korean patients with DLBCL

Real-world data on fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) findings after chimeric antigen receptor (CAR) T-cell therapy are limited in Asians. We present the findings of post-tisagenlecleucel CAR T-cell therapy PET/CT in Korean patients with diffuse large B-cell lymphoma (DLBCL). Patients who received CAR T-cell therapy for relapsed/refractory (R/R) DLBCL with follow-up FDG PET/CT within three months were included. PET/CT scans before and after CAR-T infusion were assessed using Deauville score (DS). Twenty-eight patients were included. Eighteen patients had a DS of 4–5 on post-PET/CT (DS 4, n = 3; DS 5, n = 15), and 15 progressed. In an exploratory analysis, the median PFS was shorter in the DS 4–5 group than in the DS 1–3 group (2.6 vs. 16.3 months, log-rank P = 0.0028). One post-PET/CT with a DS of 5 proved to be false-positive on follow-up, showing an ongoing response without additional treatment. Most patients with disease progression after CAR T-cell infusion had FDG-avid lesions (DS 5), except for one with a false-negative scan (biopsy-proven skin lesion). In the paired analysis of off-target organs ( n = 16), the bone marrow-to-liver and spleen-to-liver SUVmean ratios decreased after CAR T-cell infusion ( P = 0.015 and P = 0.007, respectively). Most patients with R/R DLBCL showed high metabolic activity on post-CAR-T PET/CT, with one follow-up-confirmed false-positive result. Positive findings (DS 4–5) on the initial post-CAR-T PET/CT were associated with poor prognosis for survival. These findings describe early response-assessment PET/CT performed within 1–3 months of CAR-T infusion in patients of East Asian ethnicity.