Abstract 40P
Background
Resistance to PD-1 monoblockade immunotherapies is frequent in cancer patients and associated to the up-regulation of other immune checkpoint molecules in T cells such as LAG-3. Experimental evidence suggests thad PD-1 and LAG-3 cooperatively establish a strong dysfunctional estate in T cells through co-signaling.
Methods
A high-throughput screening was performed of the PD-1/LAG-3 multiomic expression profiles in all genomics and transcriptomics public data of more than 12000 TCGA cancer patients’ samples, to establish relationships between infiltrating tumor-infiltrating PD-1/LAG-3 T cells with biomarkers both in T cells and within the tumour microenvironment. To validate these results, PD-1 and LAG-3-based molecules were engineered to provide sustained inhibitory signalling to T cells in a TCR-dependent manner. T cell lines constitutively expressing these molecules were analysed by high-throughput quantitative proteomics. We have constructed molecules that provide an initial TCR-dependent signal in T cells that lead to a sustained inhibitory activity of PD-1 and LAG-3. Global changes in the T cell proteome were identified by the action of PD-1, LAG-3 or PD-1/LAG-3 co-signaling, providing a deep scanning of PD-1/LAG-3 intracellular co-signalling pathways.
Results
The high-throughput multiomic screening and the experimental proteomic data from the T cell lines uncover a regulated genetic and proteomic programme of strong T cell dysfunctionality, which was experimentally validated by conventional techniques. The PD-1/LAG3 tumor signature represents a gene expression profile for highly dysfunctional tumor-infiltrating T cells, which correlated with the expression of other immune checkpoints, tumor microenvironment and genenomic/transcriptomic regulation molecules.
Conclusions
PD-1/LAG-3 co-signaling in tumor infiltrating T cells uncovers a regulated programme associated to strong T cell dysfunctionality, and its correlations and relationships with other immune checkpoint and tumour microenvironment molecules. These results will allow to study the reasons behind the intrinsic resistance to PD-1 blockade.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Navarrabiomed.
Funding
The OncoImmunology group is funded by the Spanish Association against Cancer (AECC, PROYE16001ESCO); Instituto de Salud Carlos III (ISCIII)-FEDER project grants (FIS PI17/02119, FIS PI20/00010, COV20/00000, and TRANSPOCART ICI19/00069); a Biomedicine Project grant from the Department of Health of the Government of Navarre (BMED 050-2019); Strategic projects from the Department of Industry, Government of Navarre (AGATA, Ref 0011-1411-2020-000013; LINTERNA, Ref. 0011-1411-2020-000033; DESCARTHES, 0011-1411-2019-000058); European Project Horizon 2020 Improved Vaccination for Older Adults (ISOLDA; ID: 848166); Crescendo Biologics Ltd. supported the OncoImmunology group for the development and testing of PD-1 and LAG-3 bispecifics.
Disclosure
All authors have declared no conflicts of interest.