New Radiation Therapy Prolongs Prostate Cancer Survival

Trials have shown that a new radiation therapy, called Xofigo, can extend the lives of men with the most advanced form of prostate cancer.Credit Bayer Healthcare Pharmaceuticals, via Pr Newswire

A new radiation therapy can extend the lives of men with the most advanced form of prostate cancer, a large new study has found.

The treatment is an isotope of radium that zeroes in on cancer cells that have spread to bones. The radium, which mimics calcium, binds with minerals in a patient’s bones, where it delivers radiation that destroys cancer cells without inflicting as much damage to surrounding tissues as older radiation therapies.


Men given the drug also experienced fewer adverse effects, like bone pain and muscle weakness.

The drug was approved by the Food and Drug Administration in May and is sold under the brand name Xofigo. The agency reviewed the drug under a fast-track priority program, approving it three months ahead of schedule.

The drug’s mechanism is not specific to prostate cancers. In clinical trials it has also shown promise in treating bone metastases resulting from breast cancer. And it is likely to help in treating bone metastases caused by other cancers as well, said Dr. Robert Dreicer, a prostate cancer specialist and the chairman of the Cleveland Clinic’s department of solid tumor oncology, who was not involved in the new research.

“I think this is a big deal,” said Dr. Dreicer said. “It’s not a home run, but it’s a nice advance.”

Prostate cancer is the second leading cause of cancer deaths among men in the United States. Every year, nearly 30,000 men die from the disease, and almost a quarter of a million new cases are diagnosed.

The cancer is usually treated with radiation or an operation that removes the prostate gland, followed by drugs that suppress the hormone testosterone, which can stimulate the growth of prostate tumors.

In many men, however, the disease eventually spreads and reaches a point where hormone therapy no longer keeps it in check. Most of the deaths from prostate cancer occur when the disease has spread to the bone.

“About 90 percent of men with advanced prostate cancer have bone metastases, and there has certainly been an unmet need for an effective treatment,” Dr. Parker said.

The new drug contains radium 223, which targets bone and emits alpha particles that are far more massive and energetic than the beta particles emitted by older radioimmunotherapies like strontium. Once in the bone, the heavier alpha particles do not stray as far as the lighter beta particles, which makes them less toxic to bone marrow, Dr. Parker said.

In the new study, Dr. Parker and his colleagues recruited more than 900 men in 19 countries who had hormone-resistant prostate cancer that had spread to their bones but not to other organs. Such men typically live for two or three years, but by the time they entered the study their disease had already progressed for some time.

The men were randomly assigned to receive either placebo or a monthly injection of Xofigo. In those who received it, the drug increased the median survival time from about 11 months to nearly 15. Dr. Parker said that in the real world, the drug could be used even earlier.

“If the drug were used earlier and the 30 percent benefit maintained,” he said, “it would give a longer absolute benefit.”

Drugs for advanced prostate cancer are typically expensive, costing tens of thousands of dollars for a single course of treatment. Xofigo is no different. A course of treatment, administered over roughly six months, costs $69,000. A spokeswoman for the drug’s developers, Bayer and its partner Algeta, said Medicare and most commercial insurers were likely to cover the drug.

In an editorial that accompanied the study, two leading radiation oncologists at the University of Pennsylvania noted that Xofigo could be used to complement other fairly new drugs that prolong survival in the late stages of the disease.

“As newer targeting molecules emerge,” they wrote, “we can envision alpha emitters as a potent partner to further enhance radioimmunotherapy and create the ultimate ‘smart bomb.’”