Eisai suffered a major pipeline blow late last week when its ovarian cancer candidate farletuzumab failed a phase III trial.
The FAR-131 trial of farletuzumab – developed by Eisai's US subsidiary Morphotek – showed that the drug was unable to improve progression-free survival (PFS) in patients with platinum-sensitive epithelial ovarian cancer who had suffered a first relapse.
In the 1,100-patient study, farletuzumab at two doses or placebo were added to a background regimen of carboplatin and a taxane drug such as paclitaxel, which is the standard treatment regimen for this type of cancer.
While the trial missed its primary endpoint, an analysis carried out after the end of the study showed that there was a trend towards improved PFS among some patients treated with farletuzumab.
Eisai needs to bring new products to market to help it cope with the loss of patent protection in the last couple of years on two blockbuster products: Alzheimer's disease treatment Aricept (donepezil) and gastrointestinal drug Aciphex (pantoprazole).
The Japanese pharma company had some success last year when partner Arena won approval in the US for obesity drug Belviq (lorcaserin), while Eisai also started to roll out new epilepsy drug Fycompa (perampanel) around the world. Both of these drugs have been tipped as potential blockbusters with $1bn-plus in annual sales.
Farletuzumab has also been tipped as a long-term blockbuster prospect for Eisai, if it could be developed in multiple cancer indications.
The drug is a humanised monoclonal antibody that binds to folate receptor-alpha (FRA), a folate-binding protein that is expressed on ovarian and several other epithelial cancers, including some forms of endometrial, breast, renal lung and colorectal cancers.
"While we are disappointed with these results, we know that ovarian cancer is a difficult disease to treat successfully," commented Dr Nicholas Nicolaides, Morphotek's chief executive.
"Morphotek remains committed to research to understand the potential role of farletuzumab in ovarian and other types of cancer."
Farletuzumab acts on the same molecular target as Merck & Co/Endocyte's vintafolide (EC145), a small-molecule drug conjugate that is in phase III trial in ovarian cancer and phase IIb testing for non-small cell lung cancer (NSCLC).
Eisai acquired Morphotek in 2007 in a $325m deal designed to bring in a portfolio of oncology drug candidates. In addition to farletuzumab, Morphotek is also developing amatuximab (MORAb-009) for mesothelioma and MORAb-004 in soft tissue sarcoma, both of which have reached phase II testing.