Merck & Co. has decided to advance a clinical development program for which it is partnered with Incyte Corporation, a Wilmington, Delaware-headquartered biopharmaceutical company, to investigate the combination of epacadostat, Incyte’s investigational oral selective indoleamine-pyrrole 2,3-dioxygenase 1 (IDO1) inhibitor, with Keytruda (pembrolizumab), Merck’s anti-programmed death (PD)-1 therapy.

With the expansion of the clinical development program, the companies plan to initiate studies of epacadostat in combination with Keytruda in four additional tumors: non-small cell lung cancer, renal cell carcinoma, bladder cancer, and squamous cell carcinoma of the head and neck. IDO1 is an immunosuppressive enzyme that modulates anti-tumor immune response by promoting regulatory T cell generation and blocking effector T cell activation, which is said to facilitate tumor growth by allowing cancer cells to avoid immune system detection, according to Incyte. Epacadostat is a selective oral inhibitor of the IDO1 enzyme that is believed to reverse tumor-associated immune suppression and restores anti-tumor immune responses, according to Incyte

The other half of the investigated therapy combination, Keytruda, is a humanized monoclonal antibody that increases the ability of the body’s immune system to help detect and deal with tumor cells by blocking interaction between PD-1 and its ligands, which activates T lymphocytes for an immune response, according to Merck. Keytruda is approved for several cancer indications, including melanoma, lung cancer, and head and neck cancer. Some analysts project that Keytruda will have blockbuster status. The drug had 2015 sales of $566 million.

Source: Merck & Co.