iFLT-PET/CT versus iFDG-PET/CT in Predicting DLBCL Outcomes

Interim 3′-deoxy-3′-[¹⁸F]fluorothymidine (iFLT) PET/CT was superior to interim ¹⁸F-fluorodeoxyglucose (iFDG) PET/CT in predicting outcomes of patients with diffuse large B-cell lymphoma (DLBCL) treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) or rituximab, etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin (R-EPOCH). This is according to a study published in the European Journal of Nuclear Medicine and Molecular Imaging.

Researchers enrolled 92 patients with DLBCL in the trial, all of whom underwent FLT-PET/CT and FDG-PET/CT roughly three weeks after two cycles of R-CHOP or R-EPOCH. iFDG-PET/CT was interpreted using Deauville-criteria, PERCIST1.0, standardized uptake value (SUV), total lesion glycolysis (TLG), and metabolic tumor volume, and iFLT-PET/CT was interpreted using dichotomous visual interpretation. Outcomes included three- and five-year progression-free survival (PFS).

iFLT-PET/CT had a higher rate of negative results, compared to iFDG-PET/CT by Deauville criteria (n=67 vs. n=53) and a lower rate of positive results (n=25 vs. n=39). Seven patients in the iFLT-PET/CT-negative group progressed at a median of 14.1 months; in the iFLT-PET/CT-positive group, 14 patients progressed at a median of 7.8 months. In the iFDG-PET/CT-negative group, nine patients progressed at a median 14.1 months, and in the positive group, 12 patients progressed at a median of 5.6 months. Multivariate analysis evaluated iFLT-PET/CT, PERCIST, interim TLG, and interim SUV_max and found that only iFLT-PET/CT independently predicted three- (P<0.0001) and five-year PFS (P=0.001).

“This multicenter head-to-head comparison shows that iFLT-PET/CT is superior to iFDG-PET/CT using both quantitative assessment and therapeutic assessment criteria in predicting PFS of DLBCL given R-CHOP or R-EPOCH and provides the rationale for using FLT-PET/CT in lieu of or in addition to FDG-PET/CT for interim response assessment of DLBCL with implications for improved patient management,” the study authors concluded.