Outcomes after first-line immunochemotherapy for primary mediastinal B cell lymphoma patients: a LYSA study.

Abstract

Primary mediastinal B-cell lymphoma (PMBL) is a rare type of aggressive lymphoma typically affecting young female patients. The first-line standard of care remains debated. We performed a large multicenter retrospective study in 25 centers in France and Belgium to describe PMBL patient outcomes after first-line treatment in real-life settings. Three hundred thirteen patients were enrolled and received rituximab (R) plus ACVBP (n=180) or CHOP delivered every 14 (R-CHOP14, n=76) or 21 days (R-CHOP21, n=57) and consolidation strategies in modalities that varied according to time and institution, mainly guided by positron emission tomography. Consolidation autologous stem cell transplantation was performed for 46 (25.6%), 24 (31.6%) and one (1.8%) patients in the R-ACVBP, R-CHOP14 and R-CHOP21 groups, respectively (p<0.001); only 17 (5.4%) patients received mediastinal radiotherapy. The end-of-treatment complete metabolic response rates were 86.3%, 86.8% and 76.6% (p=0.23) in the R-ACVBP, R-CHOP14 and R-CHOP21 groups, respectively. The median follow-up was 44 months, and the R-ACVBP, R-CHOP14 and R-CHOP21 3-year progression-free survival (PFS) probabilities were 89.4% [95% confidence interval: 84.8-94.2%], 89.4% [82.7-96.6%] and 74.7% [64-87.1%] (p=0.018), respectively. A baseline total metabolic tumor volume (TMTV) ≥360 cm3 was associated with a lower PFS (hazard ratio=2.18 [1.05-4.53]). Excess febrile neutropenia (24.4% vs 5.3% vs 5.3%, p<0.001) and mucositis (22.8% vs 3.9% vs 1.8%, p<0.001) were observed with R-ACVBP compared to R-CHOP regimens. PMBL patients treated with dose-dense immunochemotherapy without radiotherapy have excellent outcomes. R-ACVBP acute toxicity was higher than that of R-CHOP14. Our data confirmed the prognostic importance of baseline TMTV.