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Catabolic Fate and Pharmacokinetic Characterization of Trastuzumab Emtansine (T-DM1): an Emphasis on Preclinical and Clinical Catabolism

[ Vol. 13 , Issue. 7 ]

Author(s):

Ben-Quan Shen, Daniela Bumbaca, Ola Saad, Qin Yue, Cinthia V. Pastuskovas, S. Cyrus Khojasteh, Jay Tibbitts, Surinder Kaur, Bei Wang, Yu-Waye Chu, Patricia M. LoRusso and Sandhya Girish   Pages 901 - 910 ( 10 )

Abstract:


Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate in clinical development for the treatment of human epidermal growth factor receptor 2 (HER2)-positive cancers. Herein, we describe a series of studies to assess T-DM1 absorption, distribution, metabolism, and excretion (ADME) in rats as well as to assess human exposure to T-DM1 catabolites. Following administration of unlabeled and radiolabeled T-DM1 in female Sprague Dawley rats as a single dose, plasma, urine, bile and feces were assessed for mass balance, profiling and identification of catabolites. In rats, the major circulating species in plasma was T-DM1, while DM1 concentrations were low (1.08 to 15.6 ng/mL). The major catabolites found circulating in rat plasma were DM1, [N-maleimidomethyl] cyclohexane-1- carboxylate-DM1 (MCC-DM1), and Lysine-MCC-DM1. These catabolites identified in rats were also detected in plasma samples from patients with HER2-positive metastatic breast cancer who received single-agent T-DM1 (3.6 mg/kg every 3 weeks) in a phase 2 clinical study. There was no evidence of tissue accumulation in rats or catabolite accumulation in human plasma following multiple dosing. In rats, T-DM1 was distributed nonspecifically to the organs without accumulation. The major pathway of DM1-containing catabolite elimination in rats was the fecal/biliary route, with up to 80% of radioactivity recovered in the feces and 50% in the bile. The rat T-DM1 ADME profile is likely similar to the human profile, although there may be differences since trastuzumab does not bind the rat HER2- like receptor. Further research is necessary to more fully understand the T-DM1 ADME profile in humans.

Keywords:

Absorption, antibody-drug conjugate, catabolism, distribution, excretion, metabolism, T-DM1, trastuzumab emtansine, Pharmacokinetic, Trastuzumab Emtansine, HER2, Plasma, breast cancer.

Affiliation:

Genentech, Department of Pharmacokinetics and Pharmacodynamics, South San Francisco, CA 94080, USA.



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