A Real-Life Multicenter Study of Checkpoint Inhibitors in Relapsed/Refractory Primary Mediastinal B-Cell Lymphoma

Area of Science:

• Hematology
• Oncology
• Immunotherapy

Background:

• Immune checkpoint inhibitors (ICIs) have improved outcomes for relapsed or refractory (R/R) primary mediastinal B-cell lymphoma (PMBCL).
• Real-world data on ICI efficacy and optimal consolidation strategies in R/R PMBCL are limited.

Purpose of the Study:

• To evaluate the real-world effectiveness and safety of ICIs (pembrolizumab or nivolumab-brentuximab vedotin) as salvage therapy for R/R PMBCL.
• To assess the impact of consolidation strategies on long-term outcomes in R/R PMBCL patients treated with ICIs.

Main Methods:

• Retrospective observational study (PRIMICI) of 74 R/R PMBCL patients treated with ICIs in an off-label setting.
• Patients received either pembrolizumab (42) or nivolumab-brentuximab vedotin (32).
• Median follow-up of 34 months, analyzing response rates, progression-free survival (PFS), and overall survival (OS).

Main Results:

• Overall response rate (ORR) was 64%, with a complete response (CR) rate of 50%.
• Four-year disease-free survival was 100% for patients achieving CR, irrespective of consolidation.
• Estimated 5-year PFS was 60.4% and OS was 77.5%; nivolumab-brentuximab vedotin showed superior response rates and OS compared to pembrolizumab.

Conclusions:

• Pembrolizumab and nivolumab-brentuximab vedotin are safe and effective salvage therapies for R/R PMBCL.
• Durable responses are achievable with ICIs, potentially with curative intent, regardless of consolidation strategies.
• Improved OS observed post-2020 likely due to the integration of CAR T-cell therapy as a salvage option.