PD-L1 immunhistochemistry and CT scans demonstrating clinical response to therapy. (A) PD-L1 (CD274) expression by the patient’s DLBCL cells. Biopsy was obtained prior to CART19 cell infusion. Immunohistochemical staining with an anti-PD-L1 antibody from Cell Signaling (clone E1J2J, catalog number 15165BF). The main image is at ×40 magnification; the upper-right corner inset at ×100. Microscope: Leica DM 2500, lens ×10. Camera: Leica, MC 170 HD. Acquisition software: LAS V4.8. (B) CT imaging on day of pembrolizumab infusion (day 26) and 3 weeks after pembrolizumab infusion (day 45).