Eisai is celebrating the news that regulators in Europe have given the green light to its marine-derived breast cancer drug Halaven.

The Japanese drugmaker has received approval from the European Commission for Halaven (eribulin) for the treatment of patients with locally advanced breast cancer who have progressed after at least two chemotherapy regimens. Prior therapy should have included an anthracycline and a taxane unless patients were not suitable for these treatments.

The approval is based on the the Phase III EMBRACE study which demonstrated that Halaven when compared with treatment of physician's choice (TPC). That data demonstrated  median overall survival of 13.2 versus 10.5 months.

Halaven is the first single-agent therapy to demonstrate significant OS benefit in patients with advanced breast cancer and oncologists are excited about the treatment. At a recent meeting in Barcelona, Chris Twelves of the University of Leeds and co-primary investigator of EMBRACE, told PharmaTimes World News that designing a trial with an endpoint of OS and against TPC was a brave move by Eisai as it "set the bar remarkably high".

In the future, Halaven could potentially be used at an earlier stage of treatment, depending on the outcome of a trial, study 301, comparing the treatment with Roche's chemotherapy Xeloda (capecitabine). The results should be available in the next year and will also include formal quality-of-life data.

Blockbuster potential

Halaven, which belongs to a class of antineoplastic agents, the halichondrins, that are derived from the marine sponge Halichondria okadai, has the potential to be a blockbuster. It should soften the impact on earnings Eisai is going to suffer from the loss of US patent protection on its Alzheimer's disease drug Aricept (donepezil).

Eisai now plans to launch Halaven first in the UK, followed by Germany and the Nordic countries. It was approved in the USA in November 2010 (and Singapore in February this year), while other applications are currently under review in Japan, Switzerland and Canada.