Metabolic changes in reticuloendothelial system following Tisagenlecleucel chimeric antigen receptor T cell (CAR-T)...

To evaluate changes in metabolic activity in lymphoma adenopathy and other reticuloendothelial organs-bone marrow, spleen, and liver, in patients with diffuse large B-cell lymphoma (DLBCL) following Tisagenlecleucel therapy, using fluorine-18-fluorodeoxyglucse (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT).

Fluorine-18-FDG-PET/CT scans from 41 DLBCL patients (25 males, 16 females; age: 59.15±13.78, range: 29-81 years) treated with Tisagenlecleucel were retrospectively analyzed. Metabolic activity was quantified in lymphoma adenopathy, bone marrow, spleen, and liver at baseline and post-treatment, with a mean interval of 121.2±63.9 days (range: 35-437 days) between scans. The partial volume-corrected total lesion glycolysis (pvcTLG) and total metabolic tumor volume (TMTV) for lymphoma adenopathy, and average mean standardized uptake value (SUVmean) for bone marrow before and after treatment, were compared using the Wilcoxon signed-rank test, whereas the average SUVmean of spleen and liver was compared using a two-tailed paired t-test.

Fluorine-18-FDG PET/CT showed significant reductions in metabolic activity of lymphoma adenopathy, bone marrow, and spleen after treatment. For lymphoma adenopathy, pvcTLG decreased from 539.22±831.00 to 491.27±1068.35 (P<0.001), with reduction observed in 80.5% of patients, and TMTV decreased from 46.06±63.07 to 30.40±41.62 (P<0.001). Mean SUV of bone marrow and spleen decreased significantly from 1.31±0.37 to 1.16±0.33 (P=0.002), and from 1.96±0.68 to 1.77±0.45 (P=0.017), respectively. However, hepatic SUVmean showed no statistically significant changes from 2.30±0.42 to 2.31±0.40 (P=0.21).

Fluorine-18-FDG PET/CT demonstrated a decrease in metabolic activity of lymphoma adenopathy, bone marrow, and spleen, after tisagenlecleucel therapy. However, changes in the liver were not statistically significant. These findings suggest that Tisagenlecleucel chimeric antigen receptor T cell (CAR-T) therapy induces a broad systemic metabolic response within the reticuloendothelial system.