Fig. 2
From: Oncolytic viruses encoding bispecific T cell engagers: a blueprint for emerging immunovirotherapies
Oncolytic virus transgene cassettes encoding bispecific T cell engagers. Generally, BiTE sequences comprise single-chain variable fragments (scFvs) targeting CD3 (blue) and either a tumor-associated antigen (TAA, purple) or cell surface antigens expressed on cancer-associated fibroblasts (yellow) or tumor-associated macrophages (red). Variable heavy (VH) and light (VL) chains of scFvs are connected by flexible, non-immunogenic glycine-serine (G/S) linkers. Most constructs harbor peptide tags for detection and/or purification purposes (green). Transgenes are preceded by regulatory domains including promoters (F17R, SA, CMV, EF1, GRP78, GRP94), a Kozak sequence for efficient translation, and leader sequences coding for secretory signaling peptides derived from immunoglobulins (all in grey). a BiTEs specific for human Ephrin type 2 receptor (EphA2) [70] and murine fibroblast activation protein (FAP) [101], respectively, are encoded by oncolytic Vaccinia viruses (VV). b ICOVIR-15-derived adenoviral vectors have been engineered to encode BiTEs targeting human epithelial growth factor receptor (EGFR) (cBiTE) [73, 74, 86] or FAP (FBiTE, not shown) [107]. c Enadenotucirev (EnAd)-derived adenoviral vectors encode BiTEs targeting human epithelial cell adhesion molecule (EpCAM) [77], FAP (not shown) [106], or B. pertussis filamentous hemagglutinin adhesin (FHA, not shown) as a control, under control of either the constitutive cytomegalovirus (CMV) promoter or the adenoviral major late promoter via a splice acceptor (SA) site. d EnAd has also been engineered to express BiTEs specific for human folate receptor β (FRβ) or FHA (control, not shown), arranged in different orders with the CD3-targeting moiety being either C- or N-terminally [108]. e Four different BiTE transgene cassettes for oncolytic measles viruses (MV) have been designed, specific for either human or murine CD3 and either human carcinoembryonic antigen (CEA) or CD20 [82]. f Employing a combinatorial adenoviral vector system (CAd) with a replication-competent oncolytic adenovirus (not shown) and a helper-dependent vector, three immunomodulators have been encoded in cis; a BiTE targeting human CD44v6, a single-peptide interleukin-12 (IL-12p70), and an inhibitor of programmed death-ligand 1 (aPD-L1) [94]. TEA, T cell engager; F17R, late Vaccinia promoter; Ig, immunoglobulin; H-c, heavy chain; L-c, light chain; h, human; m, mouse; SA, splice acceptor for adenoviral major late promoter; CMV, cytomegalovirus promoter; HA tag, peptide from influenza A hemagglutinin; EF1, constitutive EF-1 α promoter; GRP78/94, commercial hamster and human promoters, respectively. Created with BioRender.com