CD47 Expression Defines the Efficacy of Rituximab in Non-Germinal Center B-Cell (non-GCB) Diffuse Large B-Cell Lymphoma (DLBCL)

▪ CD47 is an immune-checkpoint protein that binds SIRPa on immune cells to deliver an inhibitory “don't eat me” signal. CD47 is a prominent new target in B-cell malignancies, in which CD47 antibody in combination with the CD20 antibody rituximab (R) is explored in clinical trials. Addition of R to CHOP chemotherapy significantly improves survival of patients with DLBCL, but how CD47 expression contributes to this positive impact of R on patient outcome is currently unclear. Especially in the context of the different cell-of-origin DLBCL subtypes (Germinal Center B-cell (GCB) vs non-GCB DLBCL). We therefore investigated the impact of CD47 expression on rituximab efficacy. We first studied a clinically well annotated transcriptome cohort of 939 DLBCL patients treated with either CHOP or R-CHOP, and we validated these findings in functional in vitro assays. Our analyses showed that overall survival (OS) for patients with high CD47 expression (i.e. above median) is worse compared to patients with low CD47 expression (i.e. below median) after R-CHOP (p=0.001), but not after CHOP treatment (p=0.645). Correspondingly, patients with low CD47 expression benefited most from addition of R to CHOP (HR=0.32, CI:[0.21-0.50], p