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DAR and Drug Load Distribution Assessment

With enriched experience and profound expertise, Creative Biolabs provides elaborate analysis service for completely assessment of your ADCs drug to antibody ratio (DAR) and drug load distribution.

 DAR and drug load distribution assessment Figure: UV spectra of drug-loaded species (Antibody drug conjugates. 2013)

ADC is a class of promising target therapeutics, which composes of one or several cytotoxic drug molecules covalently linked to an antibody that binds to an antigen expressed on the surface of tumor cells. DAR, the average number of drugs conjugated to the antibody, and drug load distribution are critical quality attributes of an ADC as they measure the homogeneity of the ADC population and simultaneously determine the amount of “payload” that can be delivered to the disease tissues, which directly affect both safety and efficacy of the ADC. What’s more, comparability assessment for multiple batches of ADC samples based on the DAR values and relative drug distribution is extremely important for the quality control of ADC manufacturing, which is a time-consuming and labor-intensive process. Therefore, an elaborate analytical strategy of Creative Biolabs is integrated to help customers have a comprehensive monitoring of the DAR and drug load distribution of your ADCs. Various analytical methods are available. Ultraviolet-Visible (UV/Vis) spectroscopy is the simplest and most convenient approach for DAR determination, which works for both cysteine-linked and lysine-linked ADCs. Hydrophobic interaction chromatography (HIC) is a leading technique for the characterization of DAR values and drug loading distribution, which is often used to characterize cysteine-conjugated ADCs due to the nature of the conjugation chemistry. Furthermore, reversed phase high-performance liquid chromatography (RP-HPLC), liquid chromatography–mass spectrometry (LC-MS), liquid chromatography coupled with electrospray ionization masss pectrometry (LC-ESI-MS) are all available for determining DAR and drug load distribution of your ADCs.

Creative Biolabs is capable of offering a top-quality DAR and drug load distribution assessment to meet every customer’s requirements. Collectively, we believe our analytical strategy will be an enabling tool for the development and optimization of effective ADC candidates, providing increased confidence in results, productivity, and financial gains.

Analytical approaches for DAR and drug load distribution assessment:

  • Ultraviolet –Visible (UV/Vis) spectroscopy
  • Hydrophobic interaction chromatography (HIC)
  • Reversed phase high-performance liquid chromatography (RP-HPLC)
  • Liquid chromatography–mass spectrometry (LC-MS)
  • Liquid chromatography coupled with electrospray ionization massspectrometry (LC-ESI-MS)

The analysis services of ADC we can offer include but not limited to:


  1. Jun Ouyang. Drug-to-Antibody Ratio (DAR) and Drug Load Distribution by Hydrophobic Interaction Chromatography and Reversed Phase High-Performance Liquid Chromatography. Antibody drug conjugates. 2013.

For research use only. Not intended for any clinical use.

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