Acquired resistance to anti-PD1 therapy in patients with NSCLC associates with immunosuppressive T cell phenotype.

Immune checkpoint inhibitor treatment has the potential to prolong survival in non-small cell lung cancer (NSCLC), however, some of the patients develop resistance following initial response. Here, we analyze the immune phenotype of matching tumor samples from a cohort of NSCLC patients showing good initial response to immune checkpoint inhibitors, followed by acquired resistance at later time points. By using imaging mass cytometry and whole exome and RNA sequencing, we detect two patterns of resistance¨: One group of patients is characterized by reduced numbers of tumor-infiltrating CD8⁺ T cells and reduced expression of PD-L1 after development of resistance, whereas the other group shows high CD8⁺ T cell infiltration and high expression of PD-L1 in addition to markedly elevated expression of other immune-inhibitory molecules. In two cases, we detect downregulation of type I and II IFN pathways following progression to resistance, which could lead to an impaired anti-tumor immune response. This study thus captures the development of immune checkpoint inhibitor resistance as it progresses and deepens our mechanistic understanding of immunotherapy response in NSCLC. Acquired resistance to immune checkpoint inhibitors limits therapeutic success in non-small-cell lung cancer, however, the underpinning immune parameters are largely unknown. Here authors distinguish resistance types based on immune cell infiltration, immune checkpoint molecule and cytokine expression level, using paired samples from patients in the sensitive and in the resistant disease phase. [ABSTRACT FROM AUTHOR]