Abstract
Tandutinib (TND) is a novel, oral small molecule designed for treating acute myeloid leukemia (AML) by inhibiting type III receptor tyrosine kinases. This study reports the use of
in silico
,
in vivo
, and
in vitro
methods to investigate the metabolism and possible metabolic bioactivation of TND. First,
in silico
metabolism of TND was assessed using the WhichP450™ module of the StarDrop® software to determine labile sites of metabolism in the TND chemical structure. Second, the XenoSite reactivity model, a web-based metabolism prediction software, was used to determine probable bioactive centers. Based on the
in silico
outcomes, a list of predicted metabolites and reactive intermediates were prepared. Third,
in vitro
and
in vivo
experiments were performed.
In vitro
TND metabolites were generated through incubation of TND with rat liver microsomes (RLMs). Another incubation of TND with RLMs was separately performed in the presence of GSH and KCN to check for the generation of reactive intermediates (soft and hard electrophiles).
In vitro
phase II metabolism was assessed by incubation of TND with isolated perfused rat hepatocytes.
In vivo
metabolism was investigated by oral gavage of TND (37 mg kg
−1
) in Sprague Dawley rats. Five
in vitro
phase I metabolites, one
in vitro
phase II and five reactive iminium intermediates (cyano adducts), six
in vivo
phase I, and one
in vivo
phase II metabolites of TND were characterized. The
in vitro
and
in vivo
metabolic pathways involved were
O
-dealkylation, α-hydroxylation, α-carbonyl formation, reduction, glucuronide, and sulfate conjugation. No GSH conjugate or its catabolic products were detected either
in vitro
or
in vivo
. Two cyclic tertiary rings of TND (piperazine and piperidine) were metabolically bioactivated to generate reactive iminium intermediates forming cyano adducts with KCN. The formed reactive intermediates may be the reason behind TND toxicity.
In silico
toxicological studies were performed for TND and its related (
in vitro
and
in vivo
) metabolites were evaluated using the DEREK software tool.