MSD has received a complete response letter from the US Food and Drug Administration (FDA) relating to the new drug application for ridaforolimus.
Ridaforolimus is an investigational oral mTOR inhibitor that is under development and targeted at boosting maintenance therapy for patients with metastatic soft tissue or bone sarcoma.
However, the response letter suggests that extra clinical research would need to be conducted before the FDA can approve the application.
Eric Rubin, managing director and vice president of clinical research oncology at Merck, said: "Merck remains confident in the potential of ridaforolimus. We will continue to work closely with the FDA to define potential paths forward for this investigational therapy."
Its work on ridaforlimus is only one small part of Merck's operations, as it has announced plans to work alongside Roche to explore novel combinations of marketed and investigational medicines.
The work will aim to accelerate the availability of potential new treatment regimens for patients affected by the chronic hepatitis C virus (HCV) genotype 1 infection.