Adaptive resistance to anti-PD1 therapy by Tim-3 upregulation is mediated by the PI3K-Akt pathway in head and neck cancer

Abstract

Programmed Death 1 (PD-1) and T cell Ig and mucin domain-3 protein (Tim-3) are immune checkpoint receptors that are expressed on tumor-infiltrating lymphocytes (TIL) in tumor-bearing mice and humans. As anti-PD-1 single agent response rates are only <20% in head and neck squamous cell carcinoma (HNSCC) patients, it is important to understand how multiple inhibitory checkpoint receptors maintain suppressed cellular immunity. One such receptor, Tim-3, activates downstream proliferative pathways through Akt/S6, and is highly expressed in dysfunctional TIL. We observed that PD-1 and Tim-3 coexpression was associated with a more exhausted phenotype, with the highest PD-1 levels on TIL coexpressing Tim-3. Dampened Akt/S6 phosphorylation in these PD-1 C Tim-3 C TIL, when the PD-1 pathway was ligated, suggested that signaling cross-talk could lead to escape through Tim-3 expression. Indeed, PD-1 blockade of human HNSCC TIL led to further Tim-3 upregulation, supporting a circuit of compensatory signaling and potentially permitting escape from anti-PD-1 blockade in the tumor microenvironment. Also, in a murine HNC tumor model that is partially responsive to anti-PD-1 therapy, Tim-3 was upregulated in TIL from persistently growing tumors. Significant antitumor activity was observed after sequential addition of anti-Tim-3 mAb to overcome adaptive resistance to anti-PD-1 mAb. This increased Tim-3-mediated escape of exhausted TIL from PD-1 inhibition that was mediated by phospho-inositol-3 kinase (PI3K)/Akt complex downstream of TCR signaling but not cytokine-mediated pathways. Taken together, we conclude that during PD-1 blockade, TIL upregulate Tim-3 in a PI3K/Aktdependent manner, providing further support for dual targeting of these molecules for more effective cancer immunotherapy.

PD-1 Status in CD8+ T Cells Associates with Survival and Anti-PD-1 Therapeutic Outcomes in Head and Neck Cancer

“…As PD-1 has been shown to negatively regulate T cell phenotype, proliferation and instead induces apoptosis (13,14,28), the combination of our observations linking PD-1 and peripheral effector memory subsets in vivo supports the association of PD-1 with clonally expanded, tumor-reactive populations (11). In this situation ligation of PD-1 by its ligands is likely, and even more so for the PD-1 high expressing populations.…”

“…On the other hand, PD-1 positivity has been shown to represent antigen experienced, TA-specific T cells (11) and has been correlated with better clinical outcome (12). Additionally, other checkpoint receptors such as T cell immunoglobulin-3 (Tim-3) (13,14), Lymphocyte activation gene-3 (LAG-3) and B and T lymphocyte attenuator (BTLA) are under investigation. Tim-3 has been identified as a specific marker of fully differentiated IFN-γ producing CD4 + and CD8 + T cells (15).…”

Membranous and Cytoplasmic Expression of PD-L1 in Ovarian Cancer Cells

“…Blocking PD-1 can reinvigorate exhausted CD8 T cells and improve the control of cancer [35]. PD-1 pathway blockade also resulted in transcriptional rewiring and the reengagement of effector circuitry in the exhausted CD8 + T cells epigenetic landscape [36].…”

TIM-3 expression in breast cancer

“…Multiple studies have now reported on the presence of TIM-3+ TILs in human tumors 28-32 . However, in breast cancer, TIM-3+ TILs have been evaluated by immunohistochemistry in a limited number of patients, with one recent study reporting positive associations with lymph node metastases 33,34 .…”