LY6G6D is a selectively expressed colorectal cancer antigen that can be used for targeting a therapeutic T-cell response by a T-cell engager

Abstract

Colorectal cancer (CRC) is one of the most common cancers worldwide and demands more effective treatments. We sought to identify tumor selective CRC antigens and their therapeutic potential for cytotoxic T-cell targeting by transcriptomic and immunohistochemical analysis. LY6G6D was identified as a tumor selectively expressed CRC antigen, mainly in the microsatellite stable (MSS) subtype. A specific anti LY6G6D/CD3 T cell engager (TcE) was generated and demonstrated potent tumor cell killing and T cell activation in vitro. Ex vivo treatment of primary patient-derived CRC tumor slice cultures with the LY6G6D/CD3 TcE led to IFNγ secretion in LY6G6D positive tumor samples. In vivo, LY6G6D/CD3 TcE monotherapy demonstrated tumor regressions in pre-clinical mouse models of engrafted human CRC tumor cells and PBMCs. Lastly, 2D and 3D cocultures of LY6G6D positive and negative cells were used to explore the bystander killing of LY6G6D negative cells after specific activation of T cells by LY6G6D positive cells. LY6G6D/CD3 TcE treatment was shown to lyse target negative cells in the vicinity of target positive cells through a combined effect of IFNγ, TNFα and Fas/FasL. In summary, LY6G6D was identified as a selectively expressed CRC antigen that can be utilized to potently re-direct and activate cytotoxic T-cells to lyse LY6G6D expressing CRC using a TcE. This effect can be spread to target negative neighboring tumor cells, potentially leading to improved therapeutic efficacy.

MHC class III lymphocyte antigens 6 as endogenous immunotoxins: Unlocking immunotherapy in proficient mismatch repair colorectal cancer

“…The LY6G6D/CD3 TcE developed by (Corrales et al, 2022) similarly exhibits targeted killing of target‐positive cells in in vitro experiments where LY6G6D expression is homogeneous among cells. The pathways involved appear to be mechanistically mediated by Fas/FasL, TNFα, and IFNγ but are dispensable for the direct killing of LY6G6D expressing cells upon engagement by the TcE (Corrales et al, 2022). It is yet unknown whether the level of LY6G6D expression in clinical CRC tissues enhances the TcE's therapeutic effect.…”

“…In mouse xenograft tumor models, enhanced efficacy can be achieved when LY6G6D-TDB is combined with PD-1 blockade (Wang et al, 2022). The LY6G6D/CD3 TcE developed by (Corrales et al, 2022) similarly exhibits targeted killing of target-positive cells in in vitro experiments where LY6G6D expression is homogeneous among cells. The pathways involved appear to be mechanistically mediated by Fas/FasL, TNFα, and IFNγ but are dispensable for the direct killing of LY6G6D expressing cells upon engagement by the TcE (Corrales et al, 2022).…”

“…However, patients with pMMR CRC have not benefited from these immune modulators, and the survival outcome remains poor for the majority of patients diagnosed with metastatic CRC (Di Nicolantonio et al, 2021). Since the discovery of LY6G6D as a tumor‐associated antigen, a promising class of antibody‐based immunotherapy known as bispecific T‐cell engagers (TcEs) has been developed (Corrales et al, 2022; Wang et al, 2022). The therapeutic efficacy of TcE is well‐established in hematologic malignancies for the treatment of relapsed and refractory B‐cell acute lymphoid leukemia (Przepiorka et al, 2015).…”

“…As a result, T cells proliferate, and release immune cytokines and chemokines. Activated T cells produce perforin and granzyme B, leading to cytolysis of tumor cells (Corrales et al, 2022; Wang et al, 2022). For the treatment of CRC, two bispecific antibodies that target the membrane‐proximal epitope of LY6G6D and bind to CD3 with high affinity have recently been developed (Corrales et al, 2022; Wang et al, 2022).…”

“…Activated T cells produce perforin and granzyme B, leading to cytolysis of tumor cells (Corrales et al, 2022; Wang et al, 2022). For the treatment of CRC, two bispecific antibodies that target the membrane‐proximal epitope of LY6G6D and bind to CD3 with high affinity have recently been developed (Corrales et al, 2022; Wang et al, 2022). In vitro functional assays showed that LY6G6D‐TDB‐mediated T‐cell activation and cytotoxicity are conditional and target‐dependent (Wang et al, 2022) (Figure 4).…”