Unconjugated payload quantification and DAR characterization of antibody-drug conjugates using high-resolution MS
Leanne Grafmuller1, Cong Wei1, Ragu Ramanathan1
1Pharmacokinetics, Dynamics & Metabolism, Pfizer Inc., Worldwide Research & Development, 445 Eastern Point Road, Groton, CT 06340, USA.
Aim:
The application of high-resolution MS to antibody-drug conjugate (ADC) drug development may provide insight into their safety and efficacy. Quantification of unconjugated cytotoxic drug (payload) and characterization of drug-to-antibody ratio distribution were determined in plasma using orthogonal acceleration quadrupole-time-of-flight MS.
Results:
Unconjugated payload quantification determined by quadrupole-time-of-flight-based MRM(highresolution) and triple quadrupole-based multiple reaction monitoring were comparable and achieved detection limits of 0.030 and 0.015 ng/ml, respectively. As determined by immunocapture and TOF-MS, drug-to-antibody ratio remained unchanged up to 3-weeks postdose for an ADC containing engineered glutamine linkers, but declined from four to three over 2 weeks in an ADC containing engineered cysteine linkers.
Conclusion:
The use of high-resolution MS in ADC drug discovery confirms its utility within the bioanalytical discipline.
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