Overcoming challenges associated with the bioanalysis of cysteine-conjugated metabolites in the presence of antibody-drug conjugates.

Aim: Investigations have shown that for the antibody-drug conjugate (ADC) belantamab mafodotin, concentrations of the cysteine-conjugated metabolite, Cys-mcMMAF, were overestimated in the presence of the ADC during sample processing when utilizing a historical SPE method. Results: A new assay was developed utilizing an acidic protein precipitation to remove the ADC early in the extraction process, thus eliminating the risk of overestimating Cys-mcMMAF in the presence of belantamab mafodotin. In vitro experiments demonstrated a linear relationship between the concentration of belantamab mafodotin and the release of Cys-mcMMAF. Extensive stability assessments were performed to cover storage of study samples. Conclusion: This work emphasized the critical importance of understanding the performance of a bioanalytical method for free toxic payload in the presence of the ADC.

Antibody Subunit LC-MS Analysis for Pharmacokinetic and Biotransformation Determination from In-Life Studies for Complex Biotherapeutics.

Complex biotherapeutics present challenges from drug discovery, screening, and development perspectives. While monoclonal antibody drugs are not monitored for metabolites in the same manner as small molecules, biotherapeutics such as fusion proteins, antibody-drug conjugates, or bispecific antibodies may undergo biotransformation (such as clipping, deamidation, or oxidation) in vivo, resulting in catabolites that can have a direct impact on drug safety or efficacy. Here antibody subunit LC-MS is utilized for evaluation of two classes of complex biotherapeutics: an antibody-drug conjugate and a mAb-fusion biotherapeutic. Pharmacokinetic concentration, biotransformation, and DAR data are collectively presented using the subunit LC-MS approach for the two molecules, and the methods shared in detail can be applied to any humanized IgG1 mAb biotherapeutic for preclinical study support. Overall, the data generated from antibody LC-MS analyses can provide key information in early phase development and deliver multiple study end points with a single data set.

First-in-Human Studies for a Selective RET Tyrosine Kinase Inhibitor, GSK3179106, to Investigate the Safety, Tolerability, and Pharmacokinetics in Healthy Volunteers.

Rearranged during transfection (RET), a neuronal growth factor receptor tyrosine kinase, regulates the development of the sympathetic, parasympathetic, motor, and sensory neurons in the enteric nervous system. GSK3179106 is a RET kinase inhibitor that was administered in double-blind, randomized, placebo-controlled single-dose and repeat-dose studies in healthy subjects to investigate its pharmacokinetics and safety/tolerability. In the single-dose study (n = 16), GSK3179106 was dosed from 10 mg to 800 mg, including a food effect arm. In the repeat-dose study (n = 46), GSK3179106 was dosed for 14 days with food once daily (QD) from 5 mg to 100 mg and twice daily (BID) at 100 mg and 200 mg. With single fasted doses, bioavailability was low and less than dose proportional. A significant food effect was observed with a 100-mg QD dose. Drug exposure after QD and BID repeat dosing with food showed dose dependency up to 100 mg but was not dose proportional. There were no significant differences in exposure between 100-mg and 200-mg BID doses of GSK3179106. Accumulation was observed with both QD and BID dosing. Single doses up to 800 mg and repeat doses up to 400 mg were well tolerated with no safety concerns in healthy subjects.