FDG-PET-driven consolidation strategy in diffuse large B-cell lymphoma: final results of a randomized phase 2 study

Dose-dense induction and up-front consolidation with autologous stem cell transplantation (ASCT) remain controversial issues when treating patients with high-risk diffuse large B-cell lymphoma. GELA designed a randomized phase 2 trial evaluating the efficacy of either rituximab, doxorubicin, cyclophosphamide, vindesine, bleomycin, prednisone (R-ACVBP) or rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP14) induction and a positron emission tomography (PET)-driven ASCT or standard immunochemotherapy (SIC) consolidation in age-adjusted international prognosis index 2 (aaIPI2)-aaIPI3 patients. PET was performed at baseline, after 2 (PET2) and 4 (PET4) induction cycles, and centrally assessed using international harmonization project (IHP) criteria. PET2^-/PET4^- patients were assigned SIC, PET2⁺/PET4^- patients were assigned ASCT, and PET4⁺ patients were treated with the investigator's choice. The primary end-point was the 2007 international working group complete response (CR) rate after induction. Change in maximum standard uptake value (ΔSUVmax) after PET assessment was explored. Two hundred eleven patients were randomly assigned to R-ACVBP (n = 109) or R-CHOP14 (n = 102). PET4^-/CR rates were 53%/47% with R-ACVBP and 41%/39% with R-CHOP14 (CR 95% confidence interval [CI], 38%-67% and 28%-54%, respectively; P = .076). Consolidation in the R-ACVBP and R-CHOP14 groups was SIC in 26% and 23% of patients and ASCT in 28% and 18% of patients, respectively. PET4 positivity was higher with R-CHOP14 vs R-ACVBP (54% vs 41%; P = .08), leading to more salvage therapy (37% vs 26%; P = .07) and lower event-free survival (EFS; 4-year EFS, 31% vs 43%; P < .01), but progression-free survival (PFS) and overall survival (OS) were similar in both groups. PET2^-/PET4^- and PET2⁺/PET4^- patients had similar outcomes. Using ΔSUVmax, 79% of the patients were PET2^-/PET4^- ΔSUVmaxPET0-4 >70% was associated with better outcome (4-year PFS, 84% vs 35%; 4-year OS, 91% vs 57%; P < .0001), whatever the consolidation. Superiority of R-ACVBP over R-CHOP14 was not established, as IHP criteria did not properly reflect disease control. ΔSUVmax may help better select patients needing an alternative to SIC, including ASCT.