110MO - CD8 T cells are responsible for the PD-1, LAG-3 and CBL-B triple blockade therapeutic antitumor effect

Background

A significant number of cancer patients do not benefit from PD-L1/PD-1 blockade immunotherapies. PD-1 and LAG-3 co-upregulation in T-cells is one of the major mechanisms of resistance by establishing a highly dysfunctional state in T-cells.

Methods

PD-1/LAG-3 gene co-expression signatures were extracted from a high-throughput multiomic screening associated to T-cell functions in more than 12000 TCGA cancer patients’ data. Then, PD-1 and LAG-3 signaling pathways were co-activated in T-cells and analyzed through quantitative differential high-throughput proteomics. These results were validated by conventional molecular techniques in T-cell lines, in primary T cells from NSCLC patients and in a mice lung cancer model refractory to immunotherapy.

Results

This study shows that CBL E3 ubiquitin ligases are key targets associated to the regulation of PD-1/LAG-3 mediated T-cell dysfunctional pathways in T-cell lines and in primary T cells from NSCLC patients. PD-1, LAG-3 and CBL-B triple blockade overcomes PD-1/LAG-3 mediated resistance and T-cell dysfunctionality in a lung cancer model refractory to immunotherapies. To identify the main effector cell type for antitumor efficacy in our model, PD-1/LAG-3/CBL-B were blocked in mice depleted of CD8, CD4 or NK cells. Again, a very highly significant increase in survival was achieved for the triple combination, which more than tripled survival of PD-1/LAG-3 co-blockade alone. Importantly, only CD8 T cell depletion completely abrogated the anti-tumor efficacy of the triple PD-1/LAG-3/CBL-B blockade combination both in terms of survival and tumor growth.

Conclusions

CD8 T cells are responsible for the PD-1, LAG-3 and CBL-B triple blockade significant therapeutic antitumor effect. Patients with dysfunctional T-cell immunity resistant to conventional antibody blockade immunotherapies could benefit from immunotherapy blockade combinations with CBL-B inhibitors.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Navarrabiomed.

Funding

The Spanish Association against Cancer (AECC), PROYE16001ESCO; Instituto de Salud Carlos III (ISCIII)-FEDER Project grants FIS PI20/00010, FIS PI23/00196, COV20/00237, and TRANSPOCART ICI19/00069; Biomedicine Project Grant from the Department of Health of the Government of Navarre-FEDER funds (BMED 050-2019, 51-2021, 036-2023); 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 Union Horizon 2020 ISOLDA project, under grant agreement ID: 848166. LC is financed by Instituto de Salud Carlos III (ISCIII), co-financed by FEDER funds, “Contratos PFIS: contratos predoctorales de formación en investigación en salud” (FI21/00080). ME is financed by the Navarrabiomed-Fundación Miguel Servet predoctoral contract.

Disclosure

C.J. Edwards, J. Legg: Other, Institutional, Other, Declares to be inventor of the Humabody CB213 (WO/2019/158942. 603 Crescendo Biologics Ltd.): Crescendo Biologics. D. Escors: Other, Institutional, Other, Declares to be inventor of the Humabody CB213 (WO/2019/158942. 603 Crescendo Biologics Ltd.): Navarrabiomed. All other authors have declared no conflicts of interest.