Merck & Co has agreed to buy privately-held Scottish biopharma company IOmet in a deal that supplements the pharma group's early-stage cancer immunotherapy pipeline.
Merck (known as MSD outside North America) has not disclosed publicly how much it is paying for Edinburgh-based IOmet, which focuses on a set of molecular pathways that can encourage the immune system to recognise and attack malignant cells, although a BBC report suggested the figure could be as high as £280m.
In particular, IOmet has a preclinical pipeline of compounds that inhibit IDO1 (indoleamine-2,3-dioxygenase 1) and TDO (tryptophan-2,3-dioxygenase) - two enzymes that are often over-expressed in tumour cells, particularly in glioma, melanoma, lung ovarian and colorectal cancers.
When present at high concentrations IDO1 and TDO lead to depletion of a tryptophan, and elevated levels of metabolites such as kynurenine which according to IOmet suppress the immune response. Patients with high IDO1 and TDO tend to have worse prognosis and survival, according to the company.
The first cancer immunotherapy to reach the market was Bristol-Myers Squibb's Yervoy (ipilimumab), which has been joined more recently by BMS' Opdivo (nivolumab) and Merck's Keytruda (pembrolizumab).
Unlike these and other late-stage immuno-oncology candidates, IOmet's IDO1 and TDO inhibitors are small-molecule drugs so could be orally-active.
Other companies working in this area include Incyte, which has IDO1 inhibitor epacadostat in clinical trials, and has previously said it intends to start a combination trial with Keytruda in melanoma later this year.
NewLink Genetics also has trials of a candidate called indoximod ongoing in a range of cancers and forged a $250m alliance with Genentech for follow-up compound GDC-0919 in 2014.
Meanwhile, BMS also bought into the area via its $1.2bn purchase of Flexus last year, which included an IDO/TDO discovery programme.
IOmet also has a programme looking at the role of inhibiting the glucose transporter (GLUT1), which is also over-expressed in cancer cells and is linked to more aggressive disease and reduced patient survival time, and has a GLUT9 inhibitor programme in gout.
IOmet will become a wholly owned subsidiary of Merck after the transaction goes through, according to Merck.
IOmet's chief executive Alan Wise said becoming part of Merck "creates significant opportunity for us to advance the treatment of cancer."