Ridaforolimus is a novel small-molecule inhibitor of the protein mTOR that acts as a central regulator of protein synthesis, cell proliferation, cell cycle progression and cell survival in cancer cells. Blocking mTOR creates a starvation-like effect in cancer cells by interfering with cell growth, division, metabolism and angiogenesis.

In January 2011, ARIAD announced that ridaforolimus met the primary endpoint—improved progression-free survival compared with placebo—in the Phase 3 SUCCEED trial in patients with metastatic soft-tissue and bone sarcomas who had a favorable response to chemotherapy.

Independent review committee analysis of 552 PFS events in 711 patients found a 28 percent reduction by ridaforolimus in the risk of progression compared with a placebo. Determination of median PFS for each arm of the trial demonstrated that ridaforolimus treatment resulted in a 21 percent, or 3.1-week, improvement. Full analysis by investigative sites showed a 31 percent reduction by ridaforolimus in the risk of progression compared with placebo and a 52 percent (7.7 week) improvement in median PFS versus a placebo.

The trial remains active, with trial participants continuing to be followed to gather additional data on secondary endpoints, including overall survival, and to build the safety profile of ridaforolimus. Full press release here.

ARIAD and Merck entered into a collaboration for ridaforolimus in July 2007 and worked together to develop ridaforolimus in multiple potential cancer indications. In May 2010, both companies announced the restructuring of the partnership. Under this amended collaboration framework, ARIAD granted Merck an exclusive license to develop, manufacture and commercialize ridaforolimus in oncology, and Merck has assumed responsibility for ridaforolimus activities, including clinical trials and regulatory filings. For more information about the ARIAD-Merck collaboration, please see Our collaboration with Merck.