The US FDA has approved Bayer and Algeta’s Xofigo for castration-resistant prostate cancer (CRPC) that has spread to the bone but no other organs.
Xofigo (radium-223 dichloride) was approved three months ahead of schedule despite having already been given a fast-track review by the FDA, reflecting the importance attached to the new therapy.
The agency’s head of haematology and oncology products, Richard Pazdur, said that Xofigo is the second drug approved in the past 12 months that has been shown to lengthen survival in metastatic prostate cancer after Medivation/Astellas’ Xtandi (enzalutamide).
There is still a pressing need for new therapies for CRPC, which historically has been associated with a median survival of less than two years.
While some gains have been made in the last decade with the emergence of docetaxel/prednisone-based chemotherapy, as well as second-line therapies such as Johnson & Johnson’s Zytiga (abiraterone) and Sanofi’s Jevtana (cabazitaxel), bone metastases remain a major problem affecting 80 to 90 per cent of men who develop the cancer.
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 approval was based on the ALSYMPCA study of 809 men with symptomatic CRPC that had spread to bones but not to other organs and showed those on Xofigo lived a median of 14 months compared to 11.2 months for men receiving placebo.
Analysts have predicted that Xofigo (formerly known as Alpharadin) could achieve sales of $650m within three years of launch and more than $1bn a year at its peak if follow-up studies in combination with docetaxel are positive.
Xofigo’s emphasis on bone metastases will also insulate it from increasing competition in the CRPC market, as there are a number of new compounds coming through the pipeline.
Bayer licensed Xofigo from Norwegian firm Algeta in 2009 in a $800m deal that will see the two companies co-promote the drug in the US. It is Algeta’s first approved product.
Commercial-scale manufacturing of the drug s already underway and the first doses should be ready for administration to CRPC patients “within a few weeks”, said Bayer. A marketing application for the drug is still pending in Europe.