Pembrolizumab in Combination With R-ICE Chemotherapy in Relapsed/Refractory Diffuse Large B-cell Lymphoma

The study has two treatment arms to which participants will be randomised on a 3:1 basis to the experimental arm. The control arm (Arm A) will be R-ICE for 3 cycles followed by an autologous stem cell transplant (for patients in a CR or PR on the post treatment PET-CT scan). The experimental arm (Arm B) will consist of P+R-ICE for 3 cycles followed by an autologous stem cell transplant (for patients in a CR or PR on the post treatment PET-CT scan) and maintenance Pembrolizumab every 3 weeks for one year. All patients will be randomised at study entry and will be stratified by relapse within 12 months or \> 12 months of first line therapy.