Prognostic role of FDG-PET in patients with relapsed/refractory large B-cell lymphoma treated with CD3-CD20 directed bispecific antibodies: a multicentric analysis.

Purpose
The clinical use of CD3-CD20-directed bispecific antibodies (BsAbs) has significantly improved outcomes of patients with relapsed/refractory LBCL. However, up to 50% of patients relapse. This study evaluated the prognostic value of longitudinal FDG-PET parameters.Methods
58 patients with baseline PET and 45 (78%) with first PET after BsAb initiation were included. Standard PET metrics and Deauville score (DS) were recorded, with percent changes at follow-up defined as ΔPET parameters. Prognostic impact of DS and semi-quantitative PET metrics were determined for PFS/OS.Results
At baseline an whole-body MTV > 504.7 cm³ was associated with shorter median PFS of 1 vs. 3 months (HR = 5.6, P = 0.00025; C-index = 0.94). At first follow-up, those with DS4-5 exhibited significantly higher risk of progression (HR = 11.42, P = 0.0182; C-index = 0.97) and shorter survival (HR = 7.07, P = 0.059; C-index = 0.72). Non-achievement of ≥ 75.5% SUVmean reduction significantly increased risk for PFS (HR = 7.65; p = 0.0065; C-index = 0.92) and OS events (HR = 11.1; p = 0.001; C-index = 0.95).Conclusion
In summary, longitudinal semi-quantitative PET assessment identified patients at high risk of relapse and may enhance risk stratification and personalized management in BsAb-treated patients.