ICH6018 is a research-grade biosimilar of feladilimab (GSK3359609), supplied as an unconjugated, non-therapeutic analog of the originator antibody for research use only. It reproduces the binding specificity of feladilimab, a humanized IgG4 monoclonal directed against the inducible T-cell costimulator (ICOS/CD278), and is intended for in-vitro and functional investigation rather than clinical application. The originator was developed as an ICOS agonist immuno-oncology candidate designed to costimulate ICOS-expressing effector T cells while potentially depleting or modulating ICOS-high regulatory T cells within the tumor microenvironment. This biosimilar is produced to in-vivo research standards with low endotoxin (research grade less than 1 EU/mg; ultra-low grade less than 0.5 EU/mg) and is available in bulk milligram-to-gram quantities, supporting reproducible experiments and cross-study consistency. As a human IgG4 anti-human ICOS reagent, it is well suited to binding characterization, receptor-engagement assays, competition and epitope studies, and as a matched isotype-format control or reference standard. It provides a defined, cost-effective alternative to therapeutic material for mechanistic and screening work. Content is provided for ichor.bio to review.
ICOS (Inducible T-cell COStimulator; CD278; UniProt Q9Y6W8) is a CD28-family costimulatory receptor expressed on activated CD4+ and CD8+ T cells and constitutively at high levels on regulatory T cells. Engagement by its ligand ICOSL (B7-H2/CD275) delivers a costimulatory signal through PI3K and downstream pathways that promotes T-cell activation, proliferation, cytokine production, T follicular helper cell differentiation, and germinal center B-cell responses. In the tumor microenvironment ICOS is often enriched on intratumoral regulatory T cells, making it a dual-edged immuno-oncology target: agonism can amplify effector T-cell function, while ICOS-high Treg populations may be preferentially engaged. This biology motivated development of ICOS agonist antibodies such as feladilimab, which aim to enhance antitumor immunity through costimulation and modulation of the ICOS/ICOSL axis.
