"Site-restricted conjugation of native mAbs offers the best of two worlds"Read more
The Lx® Technology
At LinXis, we utilize the propensity of platina to coordinate to nitrogen and/or sulphur donors to link cytotoxic payloads to proteins. In a straightforward method, the cytotoxic payload is coordinated to platinum and subsequently conjugated to a monoclonal antibody.
The Lx® linker
Lx® is a cis-platin derivative comprising two reactive ligands. Replacing one these ligand by a drug affords a drug-Lx® complex serving as a semi-final product for ADC conjugation.
Special features of the drug -Lx® complexes are:
- Increased water solubility of the drug
- Long storage stability
- Lower toxicity (100 to 1000 x) compared to the free drug and to drug-linker analogues having organic linkers
Lx® can be selectively conjugated to histidines and therefore no pre-modification of mAb or mAb engineering is required for conjugation i.e. conjugation is carried out in a one-step procedure. Typically, Lx® conjugations are performed in buffered aqueous solutions under mild conditions affording conjugates with consistent characteristics:
- Drug-Lx® preferentially conjugates to the Fc region of the mAb (85%).
- DAR distribution is narrow compared to random and hinge region conjugation: site-restricted conjugation.
- In Lx®-ADCs the binding affinity of the native mAb is fully retained, which could be expected because of the preferential Fc coupling.
- Lx®-ADCs are stable in human serum.
- The biodistribution of Lx®-ADCs in mice is similar to that of the native mAb, confirming the stability of the Lx® linker.
Efficacy of Lx® based ADCs
The efficacy of Lx®-ADCs was demonstrated using a HER2 targeting ADC, AF-Lx®-Trastuzumab, conjugate which was benchmarked against T-DM1 (Kadcyla®) and an in-house prepared maleimide analogue. The in-vitro efficacies of the Lx®-ADC in HER2+ cell lines was at least as good as both benchmarks. Moreover, In the JIMT-1 cell line, a T-DM1 resistant cell line, the efficacy of AF-Lx®- Trastuzumab is more than a 100 times better than T-DM1 and about 3 times better than the cysteine conjugated ADC. Radiolabeling of the Lx®-ADC revealed excellent tumor targeting, comparable to the native mAb. Finally, the Lx®-ADC outperformed both the benchmark ADC as well as T-DM1 in a efficacy study on NCI-N87 xenografted mice.Figure 4. Efficacy of Lx® based ADCs .
What makes Lx® site-restricted conjugation more attractive than competing technologies
Both for development and production of ADCs, the Lx® platform technology makes drug conjugation an elegant, versatile, robust and facile technique: plug and play. Due to its distinguishing properties it has been introduced on the biopharma market as site-restricted conjugation. Apart from the development of our proprietary pipeline products we offer partnering for the customized development of Lx®-ADCs.