A late stage trial testing Incyte’s epacadostat in combination with MSD’s Keytruda has failed to hit its primary targets in patients with unresectable or metastatic melanoma.

The companies had been hoping that the combination of the IDO1 inhibitor and the anti-PD-1 therapy would help improve clinical outcomes for patients, but results show that it failed to improve progression-free survival in the overall population compared to Keytruda (pembrolizumab) monotherapy.

The study’s second primary endpoint of overall survival is also not expected to reach statistical significance.

On the back on the data, and on the recommendation of a data monitoring committee, the trial will now be terminated, the firms noted.

“While we are disappointed that this study did not confirm the efficacy of epacadostat in combination with Keytruda in patients with unresectable or metastatic melanoma, data from ECHO-301/KEYNOTE-252, including analyses of an extensive biomarker panel, will contribute to our understanding of the role of IDO1 inhibition in combination with PD-1 antagonists, and may inform our broader epacadostat clinical development program,” said Steven Stein, chief medical officer of Incyte.

“We remain dedicated to transforming the treatment of cancer and will continue to explore how IDO1 inhibition and other novel mechanisms can potentially improve outcomes for patients in need.”