A recent article in Cure Today describes the impact of a new class of injectable radiation therapy on Barbara Davis’ metastatic breast cancer and Dr. Howard Schiff’s metastatic prostate cancer.
Barbara Davis
Barbara Davis, a sixty-year-old CPA from Cypress, Texas, had survived breast cancer in 2007. The cancer returned in 2017, but this time it had metastasized into her bones.
Rather than treat Barbara with chemotherapy or hormonal treatments, her oncologist at MD Anderson referred her to a clinical trial testing radium 223 (Xofigo). The radiation drug is injectable and is designed to focus on cancer cells that are active in bones.
Xofigo was administered to Barbara one time each month for a period of six months. XGEVA (denosumab) a bone-strengthening drug that prevents fractures, was administered along with Xofigo. As an extra precaution for a limited time, Barbara received the hormone therapy Faslodex (fulvestrant) and Ibrance, a targeted treatment also known as palbociclib.
The treatments have diminished her bone pain and stabilized her cancer. The results of the Radium 223 clinical trial that Barbara joined showed that fifty-four percent of all participants had a response according to PET scan analysis. The median time to cancer progression was sixteen months.
Dr. Howard Schiff
In 2013, Dr. Howard Schiff was diagnosed with metastatic prostate cancer. Dr. Schiff is a urologist at Mount Sinai in New York. He responded well to his treatments with androgen deprivation therapy and Zometa that protects bones (a/k/a zoledronic acid). The therapy is an anti-hormone treatment designed primarily to treat prostate cancer.
Dr. Schiff also decided to consult with a Mount Sinai oncologist to create a “multimodal sequential therapy.” It would be a series of treatments in sequential order designed to reduce the chances of his cancer recurring.
To begin the new treatment, Dr. Schiff had his prostate removed. The next step was to be treated with docetaxel, a chemotherapy drug, for a period of six months.
Treatment then proceeded with three months taking Xtandi followed by Xofigo for another three months.
Dr. Schiff is pleased to report that he has been free of cancer since he received his last treatment in 2016. He is now seventy-one years old.
About Xofigo
The FDA approved Xofigo in 2013. It was developed to treat prostate cancer that had spread to the bone. When the drug reaches the tumor it causes double-stranded DNA breaks in the prostate cancer cells that eventually kill the cells.
Xofigo is in an expanding class of radioactive drugs called radiopharmaceuticals. These drugs can be used either for diagnostic purposes or for the treatment of cancer.
Radiopharmaceuticals differ from external beam radiation. They may be taken in pill form, injected, or inserted into the body to target active cancer cells and thus avoid damage to healthy cells.
Xofigo was approved by the FDA based on the usual series of clinical trials. Prior to approval, results of the pivotal trial showed an overall rate of survival of fifteen months compared to eleven months for the standard regimen.
The adverse effects caused by the treatment include swelling of arms or legs, low blood counts, and gastrointestinal discomfort. According to Dr. Naoto Ueno, lead investigator, several patients had bone pain upon receiving the injection as well as fatigue.
Patients who have received radiation therapy are told to avoid exposing their family and friends to radioactivity from the drug and not being in close contact for a few days.
Researchers at Michigan University and MD Anderson will be testing a combination of Xofigo and chemotherapy when they launch a trial involving metastatic breast cancer patients in the latter part of 2020.
Currently, there are fifteen FDA-approved radiopharmaceuticals related to cancer, but most are being used for diagnostic purposes.
There are four radiopharmaceuticals that are approved for treatment in addition to Xofigo:
- Hicon for cancer of the thyroid
- Lutathera treats tumors of the digestive tract
- Azedra to treat adrenal gland tumors
- Zevalin that treats non-Hodgkin lymphoma
The Future of Radiopharmaceuticals
Looking forward, researchers are discovering various methods of targeting tumors with radiation. The developer of Xofigo, Bayer HealthCare, has joined the National Cancer Institute and other institutions in studying thorium-227. The drug is linked to an antibody that can target cancer cells anywhere in the body whether they are easily identified or have not yet been detected.
Within a year, the companies will be conducting a Phase 1 study of thorium-227 conjugate in meta-static castrate-resistant prostate cancer where the cancer has spread to other parts of the body.
About Strontium 89 to Alleviate Pain
Strontium 89 has been designed to treat patients with painful cancer that has spread to the bones. Although one injection usually lasts for three months, studies indicate that the drug at times may be effective for six months. The side effects include fever, flushing, and chills.
