About GlycoConnect™ Antibody Conjugation Technology
GlycoConnect™ underpins the Synaffix ADC technology platform, utilizing enzymatic modification of the 2 naturally-occurring glycan anchor points that exist on all antibodies to facilitate efficient, site-specific and stable conjugation of potent anti-cancer molecules using extensively optimized metal-free click chemistry.
The aromatic linker stability that is afforded by the use of click chemistry ensures that more of the toxic payload reaches the targeted cancer cell, increasing efficacy, while minimizing the potential for the payload to detach prematurely in circulation, improving the safety profile. These two features, combined with the high homogeneity afforded by our approach, enhance the therapeutic index of the resulting ADC product.
The overall GlycoConnect™ process yield from the antibody starting material is typically >75% and results in a homogenous ADC drug product.
Figure 1. GlycoConnect™ chemoenzymatic antibody remodeling and conjugation process.
A. Antibody Remodeling (Chemoenzymatic)
Antibodies are modified via a highly efficient two-step, one pot process using proprietary enzymes. The first enzyme trims the glycan and the second enzyme installs a proprietary small molecule substrate bearing a functional handle exploited during subsequent conjugation.
The proprietary azide-based enzymatic substrate, used in the second step, preserves the high reactivity and selectivity afforded by conjugation via click chemistry while offering the improved ADC safety and efficacy profiles that result from the aromatically-stabilized triazole linker, formed during the reaction. Aromatically stabilized structures typically come with an order of magnitude higher stability than non-aromatic structures.
B. Payload Conjugation
Following installation of the substrate onto the antibody, GlycoConnect™ utilizes a proprietary metal-free click probe to achieve efficient and stable conjugation of potent anti-cancer molecules site-specifically, typically at a low single-digit molar excess.
Beyond metal-free click, other functional groups can be exploited that also facilitate site-specific conjugation including free thiols as well as chlorides.
Site of Conjugation is Important
It is well documented that the site of conjugation has implications for both stability and efficacy of ADCs. Given that GlycoConnect™ uses the naturally-occurring glycan that occurs at approximately the same position on all antibodies, we looked for alternate positions throughout the antibody that may be superior but were not able to identify a new site that comes with the high stability and efficacy observed with the native position. Although the stability was statistically equivalent at each site, the efficacy profile varied, as depicted to the right.
Figure 2. Efficacy comparison of glycan-conjugated ADCs varying by glycan position. Murine patient-derived xenograft (PDX) model (n = 10) using Her2+ breast cancer cell line. Partially effective single dose administration of 6 mg/kg was selected in order to best observe differences between positional ADC variants.