Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors
Clémence Demerle, Laurent Gorvel, Marielle Mello, Sonia Pastor, Clara Degos, Ana Zarubica, Fabien Angelis, Frédéric FIORE, Jacques A. Nunès, Bernard MALISSEN, Laurent Greillier, Geoffrey Guittard, Hervé Luche, Fabrice Barlési, Daniel Olive
Abstract
Background Tumor necrosis factor superfamily member 14 (TNFRSF14)/herpes virus entry mediator (HVEM) is the ligand for B and T lymphocyte attenuator (BTLA) and CD160-negative immune co-signaling molecules as well as viral proteins. Its expression is dysregulated with an overexpression in tumors and a connection with tumors of adverse prognosis. Methods We developed C57BL/6 mouse models co-expressing human (hu)BTLA and huHVEM as well as antagonistic monoclonal antibodies (mAbs) that completely prevent the interactions of HVEM with its ligands. Results Here, we show that the anti-HVEM18-10 mAb increases primary human αβ-T cells activity alone (CIS-activity) or in the presence of HVEM-expressing lung or colorectal cancer cells in vitro (TRANS-activity). Anti-HVEM18-10 synergizes with antiprogrammed death-ligand 1 (anti-PD-L1) mAb to activate T cells in the presence of PD-L1-positive tumors, but is sufficient to trigger T cell activation in the presence of PD-L1-negative cells. In order to better understand HVEM18-10 effects in vivo and especially disentangle its CIS and TRANS effects, we developed a knockin (KI) mouse model expressing human BTLA (huBTLA +/+ ) and a KI mouse model expressing both huBTLA +/+ /huHVEM +/+ (double KI (DKI)). In vivo preclinical experiments performed in both mouse models showed that HVEM18-10 treatment was efficient to decrease human HVEM + tumor growth. In the DKI model, anti-HVEM18-10 treatment induces a decrease of exhausted CD8 + T cells and regulatory T cells and an increase of effector memory CD4 + T cells within the tumor. Interestingly, mice which completely rejected tumors (±20%) did not develop tumors on rechallenge in both settings, therefore showing a marked T cell-memory phenotype effect. Conclusions Altogether, our preclinical models validate anti-HVEM18-10 as a promising therapeutic antibody to use in clinics as a monotherapy or in combination with existing immunotherapies (antiprogrammed cell death protein 1/anti-PD-L1/anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4)).