Merck & Co is expanding its clinical trials agreement with Incyte so that an experimental immunotherapy combination being assessed by the firms in skin cancer can taken into Phase III development.

The companies will co-fund a Phase III trial - pencilled in for the first half of next year - testing epacadostat, Incyte’s investigational selective IDO1 inhibitor, in combination with Keytruda (pembrolizumab), Merck’s anti-PD-1 therapy, as first-line treatment for patients with advanced or metastatic melanoma.

“We believe the combination of these two immunotherapies shows promise and, if successfully developed, may help to improve clinical outcomes for patients with metastatic melanoma,” said Hervé Hoppenot, Incyte’s president and chief executive.

The companies sealed the initial agreement to work together on the immunotherapy combo across several cancers in February last year. 

An exclusivity clause has now been added to terms of the deal, preventing the firms from embarking on any new pivotal studies of an IDO1 inhibitor/PD-1/PD-L1 antagonist combination as first-line therapy in advanced or metastatic melanoma with any third party for two years. 

Instead, the firms will each offer the other the opportunity to collaborate on any new pivotal study involving the combination for types of melanoma and lines of therapy outside of the current agreement.