In a clinical phase I trial, a patient with DLBCL of primary mediastinal origin was treated with anti-CD19 CAR T cells, and starting on day 26 after CAR T cell infusion, pembrolizumab was administered, leading to a decrease in PD-1-expressing CAR T cells, improved T cell expansion, and tumor regression [75]. Here, CD19 is linked to diffuse large B-cell lymphoma.