Xtandi Better, Cheaper than Zytiga for Treatment of mCRPC, Study Suggests

Treating chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC) patients with Xtandi (enzalutamide) leads to better survival outcomes and lower healthcare costs than Zytiga (abiraterone acetate), a study suggests.

The findings were presented at the American Urological Association’s 2019 Annual Meeting, May 3-6, in Chicago, in the study, “Survival Rates and Economic Outcomes in Chemotherapy-naive Metastatic Castrate Resistant Prostate Cancer Patients Treated with Abiraterone Acetate or Enzalutamide.”

While therapies that lower male sex hormones — required for prostate cancer to survive and grow — are a mainstay of therapy for advanced prostate cancer, most patients will acquire resistance to such approaches.

This often happens because the receptor for these hormones, called the androgen receptor, becomes constantly active, even in the absence of androgens.

Therapies that inhibit the androgen receptor — such as Pfizer and Astellas‘ Xtandi and Janssen‘s Zytiga — have largely improved the overall survival of prostate cancer patients, and are now approved for mCRPC patients in the U.S. and Europe.

However, which treatment brings the most benefits or the lowest healthcare costs has not been addressed.

In this study, researchers performed a retrospective study to compare the overall survival and healthcare costs associated with these two second-generation androgen receptor inhibitors.

They examined data from 3,174 adult men with mCRPC who had not received chemotherapy for at least one year before starting treatment with either Xtandi or Zytiga. Patients had been treated between April 2014 and March 2017, and their data were recovered from the Veterans Health Administration (VHA) database.

Overall, 1,945 patients, mean age 73, received Zytiga, while Xtandi was administered to the remaining 1,229 patients, mean age 74.

After examining outcomes of these patients, researchers found that those on Xtandi lived for a median of 30 months, compared to 26 months for Zytiga. This represented a significant 17% reduction in mortality risk with Xtandi.

Xtandi-treated patients also required fewer outpatient visits — both overall and cancer-related — than those treated with Zytiga, indicating that Xtandi led to a reduced use of medical resources.

In line with this, Xtandi patients had fewer healthcare costs than Zytiga patients. In total, a patient treated with Xtandi would have a monthly healthcare cost of $8,085, compared to $9,092 for Zytiga. Prostate cancer-related costs were also lower for Xtandi — $6,321 versus $7,280.

Thus, “chemotherapy-naive mCRPC patients treated with [Xtandi] had better survival, significantly lower resource use and healthcare costs than patients treated with [Zytiga],” researchers concluded.