Molecule of the Week

Bosutinib

September 10, 2012

Bosutinib is a tyrosine kinase inhibitor being developed by Pfizer to treat chronic myeloid leukemia. During the Phase III trials, an unusual problem occurred. N. M. Levinson at Stanford University noticed that a databank structure of bosutinib bound to a kinase was inconsistent with authentic bosutinib. It turned out that a methoxy group and two chlorine atoms on the molecule’s aniline substituent were in the wrong positions (see lower inset). An investigation showed that the “wrong” isomer has been used in many medical trials since 2006.

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