Cancer charities are disappointed with health officials who have deemed a new and 'innovative' drug to treat advanced prostate cancer is not cost-effective for the NHS.
Enzalutamide is currently available on the Cancer Drugs Fund in England, which enables patients to access drugs that would not otherwise have been routinely available from the NHS.
But the National Institute for Health and Care Excellence (Nice) has published draft guidance in which it says the drug has not been proven to work well enough for the price the NHS must pay for it.
The drug, also called Xtandi, is licensed to treat people with prostate cancer that has spread to other parts of the body who have not yet had chemotherapy, and in whom treatments to lower the amount of male sex hormones - which normally stop the cancer from growing and spreading - no longer work.
Nice said there were also too many uncertainties associated with the evidence provided by drug manufacturer Astellas Pharma.
Nice chief executive Sir Andrew Dillon said: "The clinical trial results showed enzalutamide can extend life when compared with placebo, but it was not clear for how long.
"This was because there were uncertainties associated with way the company had carried out adjustments to take account of the effect on length of life of treatments used when enzalutamide is no longer effective.
"The Appraisal Committee was also concerned that the company had not adequately evaluated the uncertainties in its cost-effectiveness analyses."
Owen Sharp, chief executive of Prostate Cancer UK, said this and other recent draft prostate cancer drug decisions "serve to reiterate the urgent need for reform of the drug appraisal process in England".
"This draft announcement once again leaves men with advanced prostate cancer in England without routine access to another clinically effective treatment," he said.
"Enzalutamide has been shown to have a great range of benefits when prescribed to men who have not previously had chemotherapy. However, what should be a cut and dry decision to recommend it seems to have come down to issues about cost and uncertainties with the clinical trial data."
Professor Paul Workman, chief executive of the Institute of Cancer Research, London, said it was "very disappointing to hear that men will not be able to receive this innovative drug earlier in their treatment.
"There is clearly an important problem that needs to be addressed urgently in order to convert more of the pioneering cancer research we've seen in recent years into concrete benefits for NHS patients."
A spokesman for Astellas Pharma said it was "disappointed" by the decision.
He said: "Astellas Pharma is hopeful that this draft recommendation will be overturned as the process moves forward, so as to give men access to a much-needed treatment option in this setting, and is committed to continuing to work with Nice to achieve this."