Bayer said yesterday the US FDA had granted fast-track status to its radiotherapeutic drug for castration-resistant prostate cancer (CRPC), raising the possibility of a launch of the potential blockbuster before year-end.
The FDA granted priority review status to radium-223 dichloride – formerly called Alpharadin – for the treatment of CRPC patients whose cancer has metastasised to the bones, setting up an eight-month review time.
Bayer licensed radium-223 dichloride from Norwegian company Algeta, which will manufacture the drug and also co-promote it in the US.
Radium-223 dichloride was filed in the US and EU towards the end of 2012, around six months later than expected owing to manufacturing problems at Algeta’s commercial-scale plant that delayed the production of three regulatory batches needed to support the marketing applications.
Analysts have predicted that the drug could hit peak sales in excess of $1bn, especially if a follow-up trial looking at its use in combination with docetaxel is positive, although CRPC has a number of new compounds coming through the pipeline which could make the market more competitive.
Andrew Kay, Algeta’s president and chief executive, has previously projected sales of $1.3bn-$1.9bn for the drug.
The marketing application for radium-223 dichloride was based on data from the phase III ALSYMPCA trial, which showed that the drug increased overall survival by 44 per cent, equivalent to a 30.5 per cent reduction in the risk of death compared to placebo. The median overall survival (OS) in patients on the drug was 14.9 months compared to 11.3 months with placebo.
Radium-223 acts as a calcium mimetic, so it preferentially targets new bone growth in and around bone metastases, emitting alpha radiation, which provides a very localised radiotherapy of the tumour sites. The isotope has a half-life of 11 days so the exposure to radiation is relatively short-term.
Bayer and Algeta are following up patients enrolled into the Alsympca study for three years, and to date there have been no reports of secondary malignancies associated with exposure to the drug.
The priority review status granted by the FDA “supports our ongoing effort to make this compound available as early as possible for patients in need of new treatment options”, said Kemal Malik, Bayer’s head of global development.
Last month the company met a key milestone for the development of radium-223 dichloride when the US Nuclear Regulatory Commission (NRC) ruled that medical sites can procure and administer radium-223 under regulations governing the medical use of radioactive byproducts. The approval recognises that standard radiation safety practices are adequate for the safe handling of the drug.