Prognostic value of pre-transplant 18-FDG PET/CT in Diffuse Large B Cell Lymphoma after R-DHAC salvage therapy

Objectives: Relapsed and refractory diffuse large B-cell lymphoma (DLBCL) are usually treated with high-dose chemotherapy (HDT) plus autologous stem cell transplantation (ASCT). 18-FDG PET/CT value has been explored in patients treated with ICE regimens before transplant. However, little is known about the value of pre-transplant 18-FDG PET/CT in the context of R-DHAC salvage therapy. Our objective was to analyze the prognostic value of PET/CT after R-CHOP salvage therapy in a pre-transplant setting.

Methods: Patients with relapsing or refractory DLBCL lymphoma who were treated with R-DHAC salvage therapy followed by ASCT were retrospectively included from 01/2008 to 05/2016. Data from 18-FDG PET/CT scans after 2 cycles of R-DHAC and before transplant were retrieved. FDG-PET scans were blindly analyzed using Deauville criteria with FDG-PET considered positive if Deauville score was stricly superior to 3. Whole-body Total Metabolic Tumor Volume (TMTV) and Total Lesion Glycolysis (TLG) were measured. IPI, age-adjusted IPI and NCCN IPI scores were retrieved. Progression Free Survival (PFS) was defined as the time from ASCT to disease progression.

Results: Sixty-five patients were included. Median follow-up was 45 months. PFS at 3 years of the entire cohort was 79% (95% CI 73.9-93.2) and overall survival was 89% (95% CI 80.4-97.7). Significant predictors of PFS on Cox univariate analysis were SUVmax (P=0.0003), a Deauville score of 5 (P=0.0129) and whole-body TLG (P=0.0065). OS was significantly associated with SUVmax (P=0.0032) and whole-body TLG (P=0.0062). No other clinical or histological parameters significantly impacted PFS or OS. Conclusion: In patients with relapsing or refractory DLBCL treated with R-DHAC salvage therapy followed by ASCT, pre-transplant 18-FDG PET/CT SUVmax and whole-body TLG remains the strongest predictive factors of PFS and OS. While a Deauville score of 5 also carries a dismal prognosis, a Deauville score of 4 does not appear to preclude a successful ASCT.