ADC payloads, linkers and linker-payloads
Small-molecule payloads and linker systems for antibody–drug conjugates: VC-PAB and alanine-alanine handles, non-cleavable linkers, and pre-activated linker-payloads (LPs) supplied to种 antibody conjugation partners under potent-compound controls.
LP
linker-payload supply
DAR 2–8
design range
Topo-I / MD
payload classes
Contained
OEB 4–5 typical
Our role in the ADC stack
Most ADC programs separate antibody production from small-molecule linker-payload manufacturing. We focus on the latter: designing and supplying LP intermediates and free payloads with impurity profiles that survive conjugation chemistry and remain stable through antibody drug product manufacture.
Technical packages include compatibility notes for cysteine rebridging, maleimide-thiol exchange risks, and aggregation triggers from hydrophobic payloads.
Linker-payload anatomy
For antibody conjugation, the small-molecule half is described in four functional zones.
- 01
Payload pharmacophore
ADC linker-payload manufacturing with HPAPI containment, impurity mapping, and conjugation-ready intermediates.
- 02
Linker body
Hydrophilic or self-immolative spacers that modulate DAR distribution, solubility, and bystander effect. Length affects ADC hydrophobicity and clearance.
- 03
Cleavage trigger
Lysosomal protease substrates (valine-citrulline, dipeptide variants) or glutathione-sensitive disulfides that control intracellular payload release.
- 04
Conjugation handle
Maleimide, bromoacetamide, or enzymatic tags that react with engineered cysteines or residues on the antibody after LP quality release.
Linker selection considerations
| Linker type | Release mechanism | Typical use |
|---|---|---|
| Valine-citrulline-PAB | Protease + PAB self-immolation | Lysosomal release; widely used |
| Non-cleavable thioether | Antibody degradation | Stability in circulation; MMAF-style |
| Disulfide bridged | Reductive intracellular | Some legacy payloads |
| Hydrophilic PEG spacer | Minimal cleavage | Improves solubility at high DAR |
Figures are indicative industry-typical values. Lot- and project-specific data appear on the quotation and certificate of analysis.
Supply formats
- Linker-payload with COA and structure confirmation
- Free payload for antibody partner re-linking studies
- Impurity reference samples for method transfer
- Stability data on LP storage (typically frozen)
- HPAPI documentation: OEB memo, cleaning summary on request
Frequently asked questions
Our core offering is linker-payload and payload chemistry. Antibody conjugation can be discussed for selected partnerships but is not the default model.
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View detailsCustom Synthesis
Multi-step organic synthesis from milligram discovery batches through kilogram pilot quantities. We support heterocycles, chiral centers, organometallics and late-stage functionalization with full analytical packages at each handoff.
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Route scouting, reaction optimization, crystallization design, and tech transfer packages that turn a workable lab sequence into a reproducible plant-ready process—without rediscovering impurities at every scale tier.
View detailsReady to specify this for your program?
Share sequence, scale and documentation needs. We reply with indicative specs and a project-specific quotation.