ALLG-PACIFIC: This study is evaluating whether combining immunotherapy with chemotherapy will improve outcomes for people with primary mediastinal B-cell lymphomaNHL35 -An Australasian Leukaemia and Lymphoma Group open label phase II study of the effect of of R-CHOP in combination with pembrolizumab in patients with newly diagnosed primary mediastinal B Cell Lymphoma (PMBL).

Summary

This study is testing whether adding immunotherapy (called pembrolizumab) to R-CHOP chemotherapy (consisting of rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) improves survival of patients with primary mediastinal B-cell lymphoma. All participants will receive the following treatment. All treatment cycles are 21 days. Cycles 1 and 2: R-pembro 'window': rituximab 375mg/m2 Intravenous infusion (IV) on Day 1 + pembrolizumab 200mg via IV on Day 1. Cycles 3-8 'Induction': rituximab 375mg/m2 via IV on Day 1, cyclophosphamide 750mg/m2 via IV on Day 1, doxorubicin 50mg/m2 via IV on Day 1, vincristine 1.4mg/m2 via IV on Day 1 capped at 2mg, prednisolone 100mg oral tablet on Days 1-5, and pembrolizumab 200mg via IV on Day 1. Cycles 9-17 pembrolizumab 'consolidation': pembrolizumab 200mg via IV on Day 1. Participants will have a PET/CT Scan at the following timepoints: after registration, after the 'pembro' phase, and after the 'induction' phase. Participants may have another PET/CT Scan at the discretion of their treating physician. Patients will also have blood samples taken every three weeks whilst receiving treatment.