Early evaluation of CAR-T cell therapy response in R/R DLBCL patients using ¹⁸F-FDG PET/CT

CD19-targeted chimeric antigen receptor T (CAR-T) cell therapy provides a durable response in patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL). The role of fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) for early evaluation of response in patients with that immunotherapy was evaluated.

Three separate ¹⁸F-FDG PET/CT examinations of 53 patients (29 males, 24 females; median 62 years old) with R/R DLBCL were conducted; before bridging therapy [time of decision (TD)], before CAR-T (tisagenlecleucel, n=37; lisocabtagenemaraleucel, n=16) infusion [time of CAR-T infusion (IT)], and one month (M1) after CAR-T infusion. Response was evaluated based on the Deauville 5-point scale and Lugano criteria.

Among 21 patients (39.6%) with complete metabolic response (CMR) at IT-PET, 20 were able to continue CMR, while one showed progression at M1-PET. Among 32 patients (60.4%) with non-CMR at IT-PET, 12, 8, 4, and 8 showed CMR, partial metabolic response (PMR), (non-metabolic response (NMR), and progressive metabolic disease (PMD), respectively, at M1-PET as compared with IT-PET. Evaluations of M1-PET as compared with baseline TD-PET indicated 32, 7, 5, and 9 patients with CMR, PMR, NMR, and PMD, respectively. After a median 10.1 months, 26 patients showed progression and 13 had died from DLBCL. The 32 who achieved CMR showed significantly longer progression-free (P<0.0001) and overall survival (P<0.0001) periods as compared to the 21 non-CMR patients.

Fluorine-18-FDG PET/CT findings obtained one month after CAR-T cell therapy showed accuracy for early response evaluation and prediction of progression in patients with R/R DLBCL.