It has to be taken with prednisone to minimize the risk of side effects affecting the digestive system. However, it is currently the standard medicine for the treatment of metastatic castration-resistant prostate cancer.
However, with the recommended 1-month dose of Zytiga coming in at $8,000–$11,000, it is an expensive drug. Many people with prostate cancer take Zytiga for 2–3 years, so the costs associated with their treatment can run into hundreds of thousands.
Currently, it is recommended that people take four 250-milligram Zytiga pills when they wake up, but that they should not eat any food overnight or eat breakfast for at least 1 hour after taking the medicine.
According to study co-author Russell Szmuletwitz, who is an associate professor of medicine at the University of Chicago, IL, "[T]his schedule is not only inconvenient for patients, it's also wasteful, in several ways."
'Effective but expensive'
A recent review of Zytiga in the New England Journal of Medicine hailed the drug for representing "a new standard of care for metastatic disease," but the article's authors also warned that the "duration and cost of treatment may influence clinical decision-making."
Prof. Szmuletwitz's colleague Prof. Mark Ratain — who is the director of the Center for Personalized Therapeutics at the University of Chicago Medicine — believes that this $10,000-per-month cost of treatment represents "a textbook example of what we now call 'financial toxicity.'"
"At least three quarters of this expensive drug is wasted," continues Prof. Ratain. "It's excreted and flushed away."
Profs. Szmulewitz and Ratain designed their randomized clinical trial to investigate whether there is a more efficient, less expensive way to use Zytiga.
They already knew that Zytiga has a greater "food effect" than any other marketed treatment. This means that the amount of the drug that is absorbed and enters a person's bloodstream can be multiplied if it is taken with an appropriate meal.
For Zytiga, this means that if the drug is taken with a 300-calorie meal, the person will absorb four to five times the amount of drug compared with if they had taken it with no food, as is currently clinically recommended.
If a person takes Zytiga with an 825-calorie meal, the absorption can be multiplied by a factor of 10.
Lower dose with food is 'equally as effective'
For the study, the researchers recruited 72 people with advanced prostate cancer. Half took 1,000 milligrams of Zytiga in the form of four pills every morning taken on an empty stomach, as is the current clinical recommendation.
The remaining participants took just one 250-milligram Zytiga pill with a low-fat breakfast.
The results revealed that participants taking the lower dose of Zytiga with a low-fat breakfast had comparable outcomes with the group taking the recommended dose. So, Zytiga seemed to work as well at controlling symptoms across both groups.
Both groups reported identical times of progression-free survival: approximately 8.6 months. The researchers also measured the extent to which Zytiga lowered levels of prostate-specific antigen (PSA), which is a marker for prostate cancer.
They found that the participants in the low-dose group experienced a slightly greater decrease in levels of PSA than the recommended dose group.
Because the drug's effect was comparable across both arms of the study, the researchers believe that taking a lower dose of Zytiga with food is more cost-effective and more convenient, without compromising on clinical benefit. The team calculate that this method of taking Zytiga may cut costs by up to $300,000 per patient.
"The patient gets a simplified schedule, slightly more control over his daily life, the convenience of eating whenever he chooses, and the opportunity to share the cost savings with his insurance company. Taking this medicine while fasting is wasteful."
Prof. Russell Szmuletwitz
If the team's results can now be validated in a larger study with more robust clinical endpoints, Prof. Szmulewitz believes that the data will "warrant consideration by prescribers, payers, and patients."
Bear in mind that more studies are now needed to confirm the findings in this study. If you have prostate cancer, you must consult your doctor before making any changes to your medication.