Comparative studies on the human serum albumin binding of the clinically approved EGFR inhibitors gefitinib, erlotinib, afatinib, osimertinib and the investigational inhibitor KP2187

Abstract

Binding interactions between human serum albumin (HSA) and four approved epidermal growth factor receptor (EGFR) inhibitors gefitinib (GEF), erlotinib (ERL), afatinib (AFA), osimertinib (OSI), as well as the experimental drug KP2187, were investigated by means of spectrofluorometric and molecular modelling methods. Steady-state and time resolved spectrofluorometric techniques were carried out, including direct quenching of protein fluorescence and site marker displacement measurements. Proton dissociation processes and solvent dependent fluorescence properties were investigated as well. The EGFR inhibitors were predominantly presented in their single protonated form (HL) at physiological pH except ERL, which is charge-neutral. Significant solvent dependent fluorescence properties were found for GEF, ERL and KP2187, namely their emission spectra show strong dependence on the polarity and the hydrogen bonding ability of the solvents. The inhibitors proved to be bound at site I of HSA (in subdomain IIA) in a weak-to-moderate fashion (logK' 3.9-4.9) using spectrofluorometry. OSI (logK' 4.3) and KP2187 can additionally bind in site II (in subdomain IIIA), while GEF, ERL and AFA clearly show no interaction here. Docking methods qualitatively confirmed binding site preferences of compounds GEF and KP2187, and indicated that they probably bind to HSA in their neutral forms. Binding constants calculated on the basis of the various experimental data indicate a weak-to-moderate binding on HSA, only OSI exhibits somewhat higher affinity towards this protein. However, model calculations performed at physiological blood concentrations of HSA resulted in high (ca. 90%) bound fractions for the inhibitors, highlighting the importance of plasma protein binding.

Development and Mechanistic Insight into the Enhanced Cytotoxic Potential of Parvifloron D Albumin Nanoparticles in EGFR-Overexpressing Pancreatic Cancer Cells

“…In this step, we aimed to assess if the EGFR inhibitors and its conjugation with BSA NPs allow or not a targeting deliver of the system to pancreatic tumour cells. Thus, the synthesis of BSA NPs conjugated with ERL or CET was performed by incubating them with a NPs suspension [45,46]. Briefly, EGFR inhibitors (500 µL) were added dropwise into the NPs suspension, followed by a 2 h reaction under stirring (500 rpm).…”

Design, synthesis and biological evaluation of pyrazolo[3,4-d]pyridazinone derivatives as covalent FGFR inhibitors

“…In contrast, the compounds 10k ( t 1/2 = 26 h), 10b ( t 1/2 = 71.2 h) and 10c ( t 1/2 = 72.9 h) showing less liability toward GSH were stable in whole blood. But beyond all that, the other compounds revealed more varied stability values and less evident relationship with structures or activation energy values, for which the stability might be also influenced by binding with other endogenously reactive components like plasma proteins 38 , 39 , 40 .…”

High-Trough Plasma Concentration of Afatinib Is Associated with Dose Reduction

“…However, precisely predicting the plasma concentration of afatinib from our result is difficult. Dömötör et al reported that human serum albumin and afatinib do not appear to show high affinity in the experimental data [ 22 ]. The difference between our data and the report is unclear.…”