One-fourth of standard dose with low-fat meal as effective as standard dose.
Taking one-fourth of abiraterone acetate (Zytiga) standard dosage with a low-fat breakfast is equally as efficacious as, and 4 times less costly, than the recommended dose, a recent study found.
Abiraterone acetate is widely used to treat castration-resistant prostate cancer (CRPC). The retail price of the drug costs more than $9000 per month, with co-pays ranging from $1000 to $3000 per month. Patients typically stay on the medication for 12 to 18 months.
The investigators sought to determine whether a low-dose with food would have similar pharmacokinetics and pharmacodynamics, and a similar safety profile to standard treatment in patients with progressive CRPC.
Included in the study were 72 patients, aged 52 to 89 years, recruited from multiple institutions in the United States and Singapore. Patients with advanced prostate cancer whose disease progressed despite standard initial hormonal therapy were randomized to receive the standard dose on an empty stomach or a low dose with a low-fat breakfast.
The primary objective was to compare the change in blood levels of PSA, according to the study.
Despite the 75% difference in dose, the results showed no difference in abiraterone activity, which was measured by variation in PSA levels between the 2 patient groups. Additionally, the time to disease progression (approximately 14 months) was virtually identical in both arms.
The investigators also found that participants who took abiraterone acetate with food were less likely to complain about stomach discomfort compared with those who took the drug on an empty stomach. The label recommends fasting for 2 hours before and 1 hour after taking the medication.
“We know this drug is absorbed much more efficiently when taken with food,” said study director Russel Szmulewitz, MD. “It’s inefficient, even wasteful, to take this medicine while fasting, which is how the drug’s label says to take it.
“Given the pharmaco-economic implications, our results warrant consideration by doctors who care for prostate cancer patients as well as payers.”
Although many oral drugs have a “food effect” that alters how the drug is absorbed, abiraterone has one of the most dramatic. When taken with a high-fat meal, blood levels of the drug can be up to 17 times higher. Taking the drug with a low-fat meal is more predictable, increasing blood levels 4- to 7-fold.
“This is a widely prescribed drug, a mainstay for patients with prostate cancer,” Szmulewitz said. “It is a great medication that has shifted the standard of care.”
Abiraterone was approved by the FDA in April 2011 for the treatment of metastatic prostate cancer. The drug differs from other treatments by delaying disease progression, deterioration of quality of life, and improving survival. When these effects diminish, they shift to a similar competing drug or move to chemotherapy.
The study findings suggest that smaller dosages taken with a low-fat breakfast would allow patients to spread the cost across 4 months rather than 1 month, saving up to $7500 per-patient per-month.
“This is a relatively small study, too small to show with confidence that the lower dose is as effective,” Szmulewitz cautioned. “It gives us preliminary but far from definitive evidence. Physicians should use their discretion, based on patient needs.”
The study is to be presented February 16, 2017, at ASCO’s 2017 Genitourinary Cancers Symposium in Orlando, FL.