A masked-antibody format that keeps the antibody dormant in circulation and switches it on only inside the tumor — widening the therapeutic window for glycan-directed therapeutics.
Conventional antibodies and antibody-drug conjugates bind their target wherever it appears — including on healthy tissue that expresses the same antigen at lower levels. This on-target, off-tumor binding narrows the therapeutic window and can drive dose-limiting toxicity, one of the central challenges in ADC development.
GlycoNex's pro-antibody format addresses this by masking the antibody's binding site with an inhibitory domain, holding it dormant while in systemic circulation. The mask is designed to be removed by proteases that are elevated in the tumor microenvironment — so the antibody is switched on selectively at the tumor while remaining inactive in circulation and normal tissue. The underlying antibody-lock technology is in-licensed from Precisemab (May 2024) and applied to GlycoNex's anti-glycan antibodies. See the Technology overview for how this fits the broader platform.
The antibody carries an inhibitory masking domain that blocks its binding site. As the pro-antibody travels through the bloodstream and normal tissue, it stays dormant — unable to engage antigen, sparing healthy cells.
In the tumor microenvironment, elevated protease activity cleaves the protease-substrate linker and removes the masking domain. Activation is localized to the tumor, where the enabling protease activity is concentrated.
With the mask removed, the antibody regains full binding activity — engaging its tumor-associated target and, in an ADC format, delivering its cytotoxic payload where it is needed while circulating-antigen interference is minimized.
The design directly targets the therapeutic-window problem: activity is gated by tumor-localized protease activity rather than by antigen distribution alone, so the format can widen the safety margin of antibodies and ADCs against antigens that are also present on healthy tissue.
Because activation restores a conventional antibody, the pro-antibody format is compatible with monoclonal antibody, ADC, and bispecific applications, and is produced through processes similar to those for conventional antibodies.
Gating activity to the tumor microenvironment reduces on-target, off-tumor binding — expanding the safety margin relative to always-on antibodies and ADCs.
By staying masked in circulation, the pro-antibody is less prone to being engaged by soluble or normal-tissue antigen before it reaches the tumor.
The masking approach is designed to minimize immunogenicity risk while the antibody circulates in its dormant form.
Applicable across monoclonal antibody, ADC, and bispecific formats, with a production process similar to that for conventional antibodies.
The format's lead application is GNX201-ADC, a pro-antibody antibody-drug conjugate targeting a tumor-associated carbohydrate antigen. It pairs GlycoNex's anti-glycan antibody with the antibody-lock format and is co-developed with Nippon Kayaku since March 2026, currently in Lead Optimization.
Because activation restores a conventional antibody, the same format can extend to future monoclonal antibody and bispecific programs built from the GlycoSH antibody bank — a route to broaden GlycoNex's glycan-directed portfolio while preserving the tumor-selectivity advantage of masked activation.
GlycoNex's pro-antibody format is open to co-development and licensing partnerships — from GNX201-ADC to new masked-antibody programs built on the GlycoSH antibody bank.
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