DrugLnk™ Custom Synthesis

The antibody portion of an antibody-drug conjugate (ADC) usually occupies over 95% of its molecular weight and it serves as a cargo to deliver the remaining ~5% to the target for a lethal strike. The warhead of this precision-guided munition is comprised of a cytotoxic payload drug and a molecular linker that covalently bridges the antibody and the payload. With an extensive library of payload drugs and linkers, plus years of experience in synthetic and conjugation chemistry, Creative Biolabs is dedicated to help our clients design and prepare highly customized linker and drug-linker complexes for the creation of ADCs using our featured “DrugLnk” services.


ADC Payloads

The payload drugs used in ADCs are highly toxic. They are small molecules that interact with intracellular targets and function as agents to block or disrupt crucial cellular metabolic pathways and eventually lead to cell death. Some payload drugs target tubular filaments and interfere with their dynamics to inhibit microtubule formation (Auristatins, Taxoids…) or cause mitosis arrest (Maytansinoids…). Other payloads inhibit crucial processes such as DNA transcription by binding to an important enzyme (Amatoxins bind to RNA polymerase) or enzyme complexes (thailanstatin A interacts with spliceosome complexes) to block transcription initiation or interfere with mRNA splicing, respectively. DNA itself is another bio-macromolecule that is frequently targeted by several payload drugs. Some payloads interact with DNA minor groove and cause DNA damage by inducing cleavages at specific sites (Calicheamicins) or by reacting with certain bases (e.g. Duocarmycins reacts with guanine). Other than the payloads mentioned before, novel chemical or biochemical entities that trigger specific downstream processes and result in cell damages, including drug carriers, proteins with toxic effects, toxic enzymes, and small molecule inhibitors targeting other crucial cellular pathways, have also been adopted as payloads.

ADC Linkers

Linkers accommodate different conjugation chemistries on both antibodies and payload drugs. They are an important portion in an ADC because they not only contribute to the stability of the complex in systematic circulation but also dictate the payload release mechanisms once internalized and trafficked into designated cellular locations. We commonly categorize linkers based on their release mechanisms into cleavable linkers (peptide linkers, β-glucuronide linkers, pH-sensitive linkers, and Glutathione-sensitivity linkers) and non-cleavable linkers.

Construction of Drug-linker Complexes

The drug-linker “warhead” is a critical component in an ADC since it largely contributes to the efficacy of the complex. It is often assembled in advance before conjugating to the antibodies and the assembly of such drug-linker sets is highly customizable and varies significantly depending on the chemistry of the payload and the linker. To accommodate such versatility, Creative Biolabs have developed the “DrugLnk” service platform—a special technical service platform based on our comprehensive understandings of the drug and linker chemistry. “DrugLnk” is tailored into two interactive modules—the drug module and the linker module that both contribute to the drug-linker “warhead” assembly.

In “DrugLnk”, we offer drug module containing various cytotoxins in the categories of:

The “DrugLnk” linker module is designated for linker design and we offer the preparation of different linker based on their drug release mechanisms:

Relying on the advanced synthetic chemistry platform and a large arsenal of in-house toxins, linkers, and drug-linker sets products at Creative Biolabs, in “DrugLnk” our experienced chemists will help clients to:

(1) Design linkers with optimal size
(2) Select linkers with suitable release mechanism
(3) Engineer linkers with compatible conjugation chemistry
(4) Synthesize customized linkers
(5) Modify payload drug
(6) Design synthesis routes
(7) Synthesize customized drug-linker complexes

Creative Biolabs is committed to provide high-quality products and chemical synthesis services to promote the progress of ADC development projects. Please contact us for more information and a detailed quote.

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