The immunocytokine PD1-IL2v overcomes resistance to tumor immunity, and synergizes with anti-PD-L1

Immunotherapies have shown remarkable, albeit tumor-selective therapeutic benefits in the clinic. Here we evaluated the effects of the immunocytokine PD1-IL2v in a mouse model of de novo pancreatic neuroendocrine cancer resistant to checkpoint and other immunotherapies. PD1-IL2v is a bi-specific molecule based on a bivalent PD-1 antibody, serving as a targeting moiety, fused to an immuno-stimulatory IL-2 variant (IL2v) to precisely deliver IL2v to PD-1+ T-cells in the tumor microenvironment. PD1-IL2v elicited dramatic infiltration by CD8 T cells, notably stem-like and effector memory T cells, resulting in tumor regression and enhanced survival in mice. Furthermore, combining anti-PD-L1 with PD1-IL2v sustained the response phase, improving therapeutic efficacy both by reprogramming immunosuppressive tumor-associated macrophages and tumor endothelial cells , and by enhancing TCR immune repertoire diversity. The data motivate consideration of clinical trials to evaluate the combination therapy of PD1-IL2v and anti-PD-L1, especially in immunotherapy-resistant tumors infiltrated with PD-1+ T stem-like CD8 T cells. Analysis of scRNAseq and scTCRseq from Rip-Tag5 PanNET mouse model (tumors and spleens) treated with PD1-IL2v, aPD-L1, PD1-IL2v + aPD-L1 or untreated for 10 days