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Releasable PEGylation

Belrose’s proprietary “releasable” linker technology was designed to free the native molecule at a controlled rate under precise conditions. This technology, which is used for Antibody Drug Conjugates (“ADCs”) provides a unique set of clinical benefits, including increased manufacturing yields retained potency, improved drug loading, pharmacokinetics and efficacy, and an abbreviated regulatory pathway.

Belrose’s proprietary releasable linker technology employs a broad range of customized linkers that reversibly tether a therapeutic moiety with PEG and release the native molecule with “no attachments”.


Range of Belrose’s proprietary releasable linkers

Belrose’s releasable linkers offer specific advantages to the linkers available from other companies

  • Control pharmacokinetics
  • Intact parential drug can be released to allow full potency of drug either inside or outside the cell
  • Random attachment sites, no need to modify the drug molecule (such as reengineering the protein)
  • High conjugate recovery and improved manufacturing yield
  • No toxicity issues found for either the linker moieties or linker conjugates
  • Dominant position in amino-based releasable linkers

The releasing of drug can be customized to be triggered by pH, plasma, enzymes, etc.

Belrose has over 40 families of patent-protected releasable linkers, including:

  • RNL system: 1, 6-benzyl elimination (BE)
  • TML system: tri-methyl lock
  • BCN system: aliphatic Bis-N-2-hydroxylethylglycinamide



Releasable PEG linkers have numerous applications for which traditional Permanent PEGylation is not suitable. Releasable PEGylation allows regeneration of authentic, fully active drug and makes it possible to tailor critical pharmacologic parameters such as maximal drug concentration and total drug exposure. Belrose’s Releasable PEGylation technology can provide a prodrug that combines the beneficial attributes of PEGylation coupled with controlled release.



Belrose Pharma can select specific Releasable Linkers and conjugation strategy to achieve specific release profiles to deliver:

  • Differentiated therapeutic value, enhanced life cycle management, and cost-effective solutions
  • Optimized solutions to the formulation challenges associated with proteins, peptides, antibodies, antibody fragments, oligonucleotides, small molecules, compounds with low solubility, bioconjugates of cytokines, immunotoxins, enzymes and siRNAs


Selected Articles on Releasable PEGylation:

Controlled Release of Proteins through Releasable PEGylation
Novel Releasable PEG-Conjugates of LNA Antisense Oligonucleotides as Potent mRNA Antagonists to Cancer Targets
Novel customized releasable polyethylene glycol linkers improve tumor delivery