Anti-PDCD1 monoclonal antibody, clone SNQ2-40 [Pacific Blue™]

It has long been understood that the immune system has intrinsic anti-tumour activity in humans, and that a key mechanism of tumour progression is the ability of a tumour to escape this immune surveillance. A number of attempts have been made to harness this anti-tumour immunity in both solid tumour oncology and haematological malignancies with variable success. Examples include the use of allogeneic stem cell transplantation and donor lymphocyte infusion in haematological cancer and vaccine studies in solid tumours. Enhanced signalling of the Programmed cell death-1 (PDCD1, PD-1)/cytotoxic T-lymphocyte-associated protein 4 (CTLA4) immune checkpoint' pathway has emerged recently as a critical mechanism by which tumours can escape the natural anti-tumour immune response. As such, novel therapies have been developed to help enhance this natural immunity by switching off the PDCD1/CTLA4 immune checkpoint pathway. The following review will discuss the pathobiology of these pathways and the exciting new data now available in lymphoid malignancies.

Immunotherapies with chimeric antigen receptor (CAR) T cells and checkpoint inhibitors (including antibodies that antagonize programmed cell death protein 1 [PD-1]) have both opened new avenues for cancer treatment, but the clinical potential of combined disruption of inhibitory checkpoints and CAR T cell therapy remains incompletely explored. Here we show that programmed death ligand 1 (PD-L1) expression on tumor cells can render human CAR T cells (anti-CD19 4-1BB.) hypo-functional, resulting in impaired tumor clearance in a sub-cutaneous xenograft model. To overcome this suppressed antitumor response, we developed a protocol for combined Cas9 ribonucleoprotein (Cas9 RNP)-mediated gene editing and lentiviral transduction to generate PD-1 deficient anti-CD19 CAR T cells. Pdcd1 (PD-1) disruption augmented CAR T cell mediated killing of tumor cells in vitro and enhanced clearance of PDL1+ tumor xenografts in vivo. This study demonstrates improved therapeutic efficacy of Cas9-edited CAR T cells and highlights the potential of precision genome engineering to enhance next-generation cell therapies.