Xofigo-Zytiga Prostate Cancer Combo Study Resulted in Increase in Deaths, Bone Fractures

After identifying an increased rate of bone fractures and deaths in a recent study involving the radiation drug Xofigo, Bayer has “unblinded” a clinical trial that was evaluating the potential use of the drug in combination with Johnson & Johnson’s hormone chemotherapy drug Zytiga.

In a press release issued last week, Bayer announced it was following recommendations from the Independent Data Monitoring Committee (IDMC) and unblinding a phase III clinical trial on a possible Xofigo/Zytiga combo drug for prostate cancer.

In a clinical trial, the term “blinded” means that neither administering doctors nor patients know if they are getting the actual drug, a placebo or some other variation of the drugs being tested. To “unblind” the trial means that Bayer is revealing to doctors and others involved in the trial which test subjects received which drugs.

The unblinding of the trial is designed to help them better understand an increase in the number of deaths and bone fracture cases among patients who were believed to have been given Xofigo.

“Patient safety is our top priority. We are therefore unblinding the study to thoroughly analyze the data,” Mike Devoy, Chief Medical Officer at Bayer, said in the press release. “It is important to note that, based on available data from previous trials as well as real-world use, the benefit-risk profile of Xofigo in its approved indication remains favorable.”

Xofigo (radium Ra 223 dichloride) is an injection that contains radioactive material. It is approved to treat metastatic castration-resistant prostate cancer that has been resistant to medical or surgical treatments and has spread to the bones. It was first approved by the FDA in 2013.

This was the third phase of clinical trials that sought to determine whether Xofigo could be used in combination with steroids and Zytiga, which is a hormone-based chemotherapy drug also used to treat prostate cancer.

The randomized double-blind, placebo-controlled clinical trial involved more than 800 patients and began in September 2016. While neither Bayer nor the IDMC issued actual numbers on fractures and deaths, the IDMC, which can view the unblinded data as it ensures the safety of such clinical trials, notified the company of the increased fractures and deaths among patients receiving Xofigo and called for the company to unblind the trial to look at the data.

The press release does not indicate whether the trial has been cancelled or just halted.