Patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) who received the CAR T-cell therapy tisagenlecleucel often showed high metabolic activity on fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) scans performed after infusion, according to a preliminary study of Korean patients published in EJNMMI Research. Positive findings on these early scans, scored as Deauville 4 or 5, were associated with poorer survival, although one such positive scan ultimately proved to be false.
The study addressed a gap in real-world evidence. The authors note that data on FDG PET/CT findings after CAR T-cell therapy are limited in Asian populations, and their cohort describes early response-assessment imaging performed within one to three months of CAR-T infusion in patients of East Asian ethnicity.
To conduct the analysis, the researchers enrolled patients who had received CAR T-cell therapy for relapsed or refractory DLBCL and who had a follow-up FDG PET/CT scan within three months of treatment.
Twenty-eight patients were included in the study. On the post-treatment PET/CT scans, eighteen patients had a Deauville score of 4 or 5, with three scoring 4 and fifteen scoring 5. Of those eighteen patients with positive scans, fifteen experienced disease progression.
The prognostic implications emerged in an exploratory analysis of survival. Median progression-free survival was shorter in the group with Deauville scores of 4 to 5 than in the group with scores of 1 to 3: 2.6 months compared with 16.3 months, a difference that reached statistical significance with a log-rank P value of 0.0028. This association suggests that the initial post-CAR-T PET/CT may help identify patients at higher risk of early progression.
The study also documented the pitfalls of early imaging. One post-treatment scan with a Deauville score of 5, the highest avidity category, turned out to be false-positive on follow-up: the patient showed an ongoing response without any additional treatment.
On the other side of the diagnostic spectrum, most patients whose disease progressed after CAR T-cell infusion had FDG-avid lesions scoring 5 on their scans. There was one exception: a false-negative scan in a patient whose progression was confirmed by biopsy of a skin lesion. This case illustrates that a negative post-treatment PET/CT does not completely exclude progression.
Beyond lesion assessment, the researchers performed a paired analysis of off-target organs in sixteen patients. They measured the average standardized uptake values, or SUVmean, of the bone marrow and spleen relative to the liver before and after CAR-T infusion. Both the bone marrow-to-liver and spleen-to-liver SUVmean ratios decreased after infusion, with P values of 0.015 and 0.007 respectively.
The authors concluded that most patients with relapsed or refractory DLBCL in their cohort showed high metabolic activity on post-CAR-T PET/CT, with one follow-up-confirmed false-positive result, and that positive findings of Deauville score 4 or 5 on the initial post-treatment scan were associated with poor prognosis for survival. As a preliminary, single-country study of 28 patients, the findings describe imaging patterns in an East Asian population rather than establishing new clinical practice guidelines, and the survival analysis was explicitly labeled exploratory.
Subject of Research: FDG PET/CT imaging findings after CAR T-cell therapy in Korean patients with relapsed or refractory diffuse large B-cell lymphoma
Article Title: Post-chimeric antigen receptor T-cell fluorodeoxyglucose positron emission tomography-computed tomography findings in Korean patients with DLBCL
Article References: Kwon, S. J., O, J. H., Min, G.-J., Park, G., Choi, B.-O., Choi, J.-I., Eom, K.-S., & Cho, S.-G. (2026). Post-chimeric antigen receptor T-cell fluorodeoxyglucose positron emission tomography-computed tomography findings in Korean patients with DLBCL. EJNMMI Research. https://doi.org/10.1186/s13550-026-01525-6
Image Credits: AI Generated
DOI: 10.1186/s13550-026-01525-6
Keywords: CAR T-cell therapy, tisagenlecleucel, DLBCL, FDG PET/CT, Deauville score, lymphoma, progression-free survival, false-positive, Korea, nuclear medicine, relapsed refractory, response assessment
News Source: Nathaniel Bowman. (October 29, 2026). PET/CT Scans After CAR T-Cell Therapy Track Response in Korean Lymphoma Patients. Scienmag.
