Ken Surprenant’s wife Kathryn was diagnosed with rectal cancer in 2012. She started chemotherapy, but the treatment to prolong her life ended it.
It turned out she could not metabolize the cancer drug fluorouracil or 5-FU. Ken Surprenant says a simple blood test can prevent deaths from the drug. And the FDA should require it.
Surprenant says as many as 1300 people die each year in the U.S. because they cannot metabolize fluoropyrimidine drugs like fluorouracil (5-FU) and capecitabine (Xeloda). These are the common drugs used to treat colorectal cancer, and certain breast, head and neck cancers.
“I know that you hear the big C word, we get shocked and we put a lot of trust in the doctors. And we should, but patients need to be their own advocates as well,' Surprenant said.
Surprenant is the president of the group Advocates for Universal DPD/DPYD Testing (AUDT).
DPYD is the name of the gene that tells the body to produce an enzyme called dihydropyrimidine dehydrogenase (DPD). DPD is needed to breakdown and excrete fluoropyrimidine drugs like 5-FU. But people with a DPD deficiency may not even know they have the condition, making them vulnerable to a toxic reaction if treated with these drugs.
“We’re not trying to dissuade you from getting treatment," he said. "We want to make that perfectly clear. We’re not trying to scare anybody from talking to oncologists and getting treatment. What we want you to do is have a conversation with your oncologist and say ‘I understand that there’s a risk.’”
In March, the FDA added stronger language on the label about the fatality risk associated with fluoropyrimidine drugs like 5-FU. The new label now encourages the blood test before treatment.
When the change was announced, AUDT called it a step in the right direction. But the group was disappointed the FDA did not require screening before treating cancer patients.
Daniel Hertz is a University of Michigan cancer researcher and pharmacogenetics expert. He studies how patients’ genes affect their response to treatment. He said requiring a blood test before treatment lets doctors know if a patient can handle the drug. If the patient can’t handle the drug, the doctor can lower the dosage or recommend another course of action.
Hertz said the FDA has done it before. In 2008, the agency issued a “black box” warning for the HIV medication abacavir. The agency also mandated testing before treatment.
“They could have done the same here,” Hertz said. “They could have put a box warning on the 5-FU label that said testing for DPYD is required prior to administration of fluorouracil (5-FU) treatment. And that would have essentially made this a requirement for all clinicians. It would have made this standard of care across the United States.”
Hertz and Surprenant applaud a Veterans Administration program to ensure veterans get a blood test before treatment for a variety of illnesses like depression, blood clots and cancer. The program was rolled out in 2019 at a few sites. The Pharmacogenomics Testing for Veterans Program, or PHASER, is expanding. It came to Battle Creek in October.
Sara Shikwana is the clinical pharmacist responsible for implementing pharmacogenomics of the PHASER Program at the Battle Creek VA.
“We're basically trying to look and see if your genes are putting you at a higher risk for side effects. Are your genes preventing your body from getting the most benefit of certain medications?”
Shikwana said the condition that caused Kathryn Surprenant’s reaction to the chemotherapy drug 5-FU effects up to 2.4% of the population. She also said the FDA’s decision to add stronger warning labels supports the PHASER Program, but even the VA doesn’t require mandatory testing at this time.
“Right now, we're working on the process to have this testing required prior to referral to certain chemotherapy treatment. So, this is something that we are working on, but right now it is not required. It is encouraged.”
Shikwana said the PHASER test is free to veterans.