Merck & Co and partner Ariad Pharmaceuticals say the US Food and Drug Administration has accepted its file for its sarcoma drug ridaforolimus.

Specifically, the drug, which is an oral mTOR inhibitor, is under development for the treatment of metastatic soft-tissue or bone sarcomas in patients who had a favourable response to chemotherapy. The FDA has assigned a standard review classification to the firms' application.

The news comes a couple of months after the European Medicines Agency agreed to start reviewing a marketing application for the drug. Earlier this year, Merck and Ariad reported data from the SUCCEED trial showing that ridaforolimus induced a significant 28% reduction in the risk of disease progression compared to placebo.

As part of the agreement with Ariad, signed in May 2010, Merck is responsible for the development and worldwide commercialisation of ridaforolimus. However, Ariad intends to co-promote the drug in the USA.

Merck and Ariad are also looking at ridaforolimus in early- to mid-stage clinical testing for endometrial, breast and ovarian cancers, as well as renal cell carcinoma. The mTOR inhibitor class is currently led by Novartis' Afinitor (everolimus), which is approved for second-line treatment of advanced renal cell carcinoma and the treatment of pancreatic neuroendocrine tumours.