Drs. Alicia Morgans and Phillip Koo discuss Radium-223 as a treatment option for advanced prostate cancer patients.

* This year (2023), Xofigo is celebrating its 10-year anniversary as an innovative treatment option for patients with metastatic prostate cancer*

For men with metastatic castration resistant prostate cancer (mCRPC), their prostate cancer has gotten worse and moved outside the prostate gland (i.e., bones, lymph nodes, etc.) despite being on androgen deprivation therapy (ADT). There are several treatment options for mCRPC, but one in particular has been FDA approved and available to patients since 2013: Radium-223 (trade name: Xofigo), which is specifically approved for men with mCRPC and painful bone metastases (prostate cancer that has spread to the bone) but without other organ spread (e.g., to the lung, liver).

What is Radium-223 and how does it work?

Radium-223 is a type of radiation (radioactive) treatment that impersonates calcium, giving off alpha particles (the active form of radiation), which causes damage to DNA. When DNA is damaged, the prostate cancer cells die. Because Radium-223 acts like calcium, it goes to locations where there is lots of “bone turnover,” such as areas in the bone where prostate cancer has spread. This feature, plus the short range of activity of activity of alpha particles, leads to limited damage to normal surrounding cells and tissue.

How well does Radium-223 work?

In 2013, the ALSYMPCA trial showed that men receiving Radium-223 lived longer than men that did not receive Radium-223. More specifically, men receiving Radium-223 lived an average of 14.9 months compared to 11.3 months for men receiving “best standard of care”, leading to a 30% reduction in risk of dying for those men receiving Radium-223. As well as extending men’s lives, Radium-223 also led to a longer time to first symptomatic skeletal event. This was defined as receiving radiation therapy for painful bone metastases, new painful bone fracture due to prostate cancer, spinal cord compression, or prostate cancer related surgical procedures to the bone. Men receiving Radium-223 had an average of 15.6 months before their first symptomatic skeletal event, compared to 9.8 months for men receiving “best standard of care”, leading to a 34% risk reduction in the time to first symptomatic skeletal event for men receiving Radium-223. Radium-223 has a favorable safety profile and minimal side effects and myelotoxicity. This treatment offers a change in how this treatment works compared to others used in mCRPC.

How is Radium-223 given?

Radium-223 is given as an injection into one of your veins, with the injection only taking about 1 minute. Treatment is usually given every 4 weeks and usually given 6 times in total. This is an outpatient procedure, and you are able to go home after the injection. Between treatments you will likely have blood tests to make sure the treatment is not going to increase your risk of getting an infection (low blood count).

What can I expect after Radium-223 treatment?

After reach treatment, there may be some radiation present in your urine and stool for up to 7 days, with the amount getting lower each day. It is important to drink plenty of fluids after treatment, sit to urinate (rather than stand), flush the toilet twice after using it, and wash your hands well after using the toilet. For men that wish to father children, they should wait for approximately 6 months after Radium-223 to do so, as the effect of treatment may lead to sperm damage. The side effects of Radium-223 are diarrhea and feeling unwell (nausea and vomiting), and these symptoms are typically mild. Treatment may also lead to anemia (low blood count), which can increase the risk of infection and bruising.

Men with mCRPC with painful prostate cancer bone metastases and no evidence of visceral (i.e., lung, liver) metastases are candidates for Radium-223. Although there are several options for treatment for men with mCRPC, those with these key criteria who receive Radium-223 have a 30% decreased risk of dying and a 34% risk reduction in getting a symptomatic skeletal event. Thus, Radium-223 can improve survival and prevent painful bone complications from prostate cancer. Because there is a limited number of side effects for men receiving Radium-223, with ~4 weeks in between treatments, most men can continue working and lead normal lives during their treatment course.

Zachary Klaassen, MD, MSc
Urologic Oncologist, Georgia Cancer Center, Augusta University, Augusta, GA, USA

Rashid Sayyid, MD, MSc
Urologic Oncology Fellow, University of Toronto, Toronto, ON, Canada