Anti-BTLA monoclonal antibody, clone 5E7

Co-signaling molecules have been demonstrated to regulate regulatory T cells' (Tregs) function during human immunodeficiency virus (HIV) infection. A recently reported co-signaling molecule called herpes virus entry mediator (HVEM), a member of the tumor necrosis factor receptor family, can both enhance and inhibit the immune response. HVEM was also reported to enhance the suppressive function of regulatory T cells in mice. However, it remains unknown whether HVEM can regulate Treg function in HIV-infected patients or whether HVEM affects HIV disease progression. In this study, we found that the blockage of the HVEM could weaken Tregs' suppressive activity to effector T cells (Teffs). HVEM expression is reduced during the asymptomatic phase of HIV infection and fairly predictive of the recovery of CD4+T-cells in response to highly active anti-retroviral therapy (HAART), more so than nadir CD4+T-cell count or viral load. Taken together, these findings demonstrate the importance of HVEM in relation to Treg function and HIV disease progression, which would have therapeutic implications and provide insight into the pathogenesis of acquired immune deficiency syndrome (AIDS).

Tumor cells may express on their surface various characteristic antigens that can induce antitumor immunity. However, cancer in human body may induce an immunosuppressive microenvironment that limits immune response to its antigens. For many years scientists have tried to develop an immunotherapy which would induce a potent antitumor immune response and lead to an elimination of the disease. One of the most promising immunotherapies is blockade of immune checkpoints, i.e. a group of costimulatory molecules negatively regulating the immune system. Their blockade would overcome immune tolerance in the tumor microenvironment and amplify antitumor immunity. What's more, immune checkpoint blockade may turn out even more profitable, as some of immune checkpoints and their ligands are expressed on tumor surface and on tumor infiltrating lymphocytes, contributing to the immunosuppressive cancer microenvironment. Phase III clinical trials have confirmed efficacy of an anti-CTLA-4 antibody ipilimumab, thereby leading to its acceptance for the treatment of advanced melanoma. Thanks to promising results of the phase I clinical trials, a breakthrough therapy designation and an early approval for the treatment have been granted to anti-PD-1 antibodies - nivolumab (for the treatment of advanced melanoma and advanced non-small cell lung cancer) and pembrolizumab (for the treatment of advanced melanoma) and, in the treatment of advanced bladder cancer, an anti-PD-L1 antibody - MPDL3280A as well. Other immune checkpoints, such as LAG-3, TIM-3, BTLA, B7-H3 and B7-H4, are also under early evaluation.