Indrani Chakraborty

Novel detection of DNA-alkylated adducts of antibody–drug conjugates with potentially unique preclinical and biomarker applications

BACKGROUNDnMDX-1203 is an antibody-drug conjugate (ADC) currently in clinical trials for the treatment of renal carcinoma. The active ingredient of MDX-1203 is a DNA minor groove-binding cytotoxic drug that forms a covalently linked adduct with an adenine base. Formation of this adenine adduct prevents DNA replication, thus triggering cell death.nnnRESULTSnA method has been developed to successfully isolate, identify and quantitate the adenine adduct using LC-MS/MS. The method is highly useful to validate the mode of action of this class of ADCs. Additionally, we have demonstrated that this method could potentially be utilized to assess the efficacy of the ADC in in vitro studies by measuring the amount of adenine adduct in various cells expressing the antigen.nnnCONCLUSIONnUpon validation, this method could serve as an invaluable tool to evaluate compounds in preclinical in vivo models and in utilizing the DNA adduct as a potential biomarker.

Abstract 2446: Biodistribution of antibody drug conjugates by LC-MS

Introduction: A method to study biodistribution of adduct forming antibody drug conjugates (ADCs) by LC-MS Description: ADCs are increasingly used to deliver cytotoxic payloads to tumor cells. While the targeted approach has vastly improved the toxicity profiles of these drugs, it is still important to understand the bio-distribution and the enhanced tumor localization this approach offers. Radio-labeled methods are still the most reliable approach to study the bio-distribution, but may not be able to differentiate between the drug that is present in the tissue from those that have formed covalent adducts upon non-specific internalization. Here, we describe a mass-spectrometric methods to identify these covalent adducts these cytotoxic agents form and how such methods could be utilized to map the bio-distribution in xenograft models. Data: The antibody drug conjugate is highly localized in the tumor with a %ID/gm value of almost 40 within 24 hours of dosing and no non-specific accumulation in other organs observed. Conclusions: A simple and robust LC-MS based method has been developed to understand the bio-distribution of antibody-drug conjugates by detecting and quantifying the actual and final chemical state of the toxin in the targeted cell. This method could be used to evaluate the (1) PK of antibody-drug conjugates (2) make lead selections at advanced preclinical stages of antibody-drug development (3) understand the ADME properties of the chosen antibody-drug conjugate Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2446.