Background:Despite the early success of Bruton's tyrosine kinase (BTK) inhibitors in the treatment of
Waldenström macroglobulinemia (WM), these single-target drug therapies have limitations in their clinical applications,
such as drug resistance. Several alternative strategies have been developed, including the use of dual inhibitors,
to maximize the therapeutic potential of these drugs.Objective:Recently, the pharmacological activity of KIN-8194 was repurposed to serve as a ‘dual-target’ inhibitor of
BTK and Hematopoietic Cell Kinase (HCK). However, the structural dual inhibitory mechanism remains unexplored,
hence the aim of this study.Methods:Conducting predictive pharmacokinetic profiling of KIN-8194, as well as demonstrating a comparative
structural mechanism of inhibition against the above-mentioned enzymes.Results:Our results revealed favourable binding affinities of -20.17 kcal/mol, and -35.82 kcal/mol for KIN-8194 towards
HCK and BTK, respectively. Catalytic residues Arg137/174 and Lys42/170 in BTK and Arg303 and
Lys75/173/244/247 in HCK were identified as crucial mediators of the dual binding mechanism of KIN-8194, corroborated
by high per-residue energy contributions and consistent high-affinity interactions of these residues. Prediction of
the pharmacokinetics and physicochemical properties of KIN-8194 further established its inhibitory potential, evidenced
by the favourable absorption, metabolism, excretion, and minimal toxicity properties. Structurally, KIN-8194
impacted the stability, flexibility, solvent-accessible surface area, and rigidity of BTK and HCK, characterized by
various alterations observed in the bound and unbound structures, which proved enough to disrupt their biological
function.Conclusion:These structural insights provided a baseline for the understanding of the dual inhibitory activity of KIN-
8194. Establishing the cruciality of the interactions between the KIN-8194 and Arg and Lys residues could guide the
structure-based design of novel dual BTK/HCK inhibitors with improved therapeutic activities.