Merck announced that it has acquired IOmet, a privately-held UK-based
drug discovery company focused on the development of innovative
medicines for the treatment of cancer, with a particular emphasis on the
fields of cancer immunotherapy and cancer metabolism. Under terms of the
agreement, Merck, through a subsidiary, will acquire IOmet, including
its comprehensive pre-clinical pipeline of IDO
(indoleamine-2,3-dioxygenase 1), TDO (tryptophan-2,3-dioxygenase), and
dual-acting IDO/TDO inhibitors. Based on the transaction, IOmet will
become a wholly owned subsidiary of Merck.
IDO1 and TDO, the rate-limiting enzymes in the pathway that metabolizes
the essential amino acid tryptophan, have emerged as key targets for the
pharmaceutical industry in the cancer immunotherapy field.
Overexpression of these enzymes has been detected in a variety of
cancers – including glioma, melanoma, lung, ovarian, and colorectal
cancers – and is associated with poor prognosis and survival. IDO1 and
TDO overexpression leads to tryptophan depletion and high tumor levels
of the breakdown product, kynurenine. This elevated
kynurenine/tryptophan (K/T) ratio suppresses the body’s immune response
to cancer, thus facilitating tumor progression and metastasis. Extensive
preclinical evidence, and emerging clinical data, suggests that
inhibition of IDO1 and/or TDO may synergize with, and help overcome
resistance to, existing clinical cancer therapies, in particular other
immunotherapy-based treatments.