- Pfizer and Astellas Pharma released data Monday showing a combination of Xtandi and androgen deprivation therapy (ADT) significantly reduced the risk of death or radiographic progression by 61% compared to ADT alone in a certain type of prostate cancer.
- The partnered companies had announced the success of the Phase 3 ARCHES study last December. Monday's update gives a fuller sense of the trial, showing the drug improved radiographic progression-free survival in men with metastatic hormone-sensitive prostate cancer (mHSPC).
- Results from ARCHES, along with other Xtandi data, will be presented at the 2019 Genitourinary Cancers Symposium in San Francisco on Thursday. Pfizer and Astellas plan to discuss these results with global health authorities to extend Xtandi's approval.
Last July, Xtandi (enzalutamide) became the first oral treatment approved by the Food and Drug Administration for the treatment of both non-metastatic and metastatic castration-resistant prostate cancer, securing a label expansion after presenting data in non-metastatic patients at last year's Genitourinary Cancers Symposium.
Clinical success has carried over into the commercial setting, with Pfizer recently reporting alliance revenues for Xtandi increased by 18% year over year in 2018.
Pfizer expects to see growth for Xtandi to continue, especially as the drug moves into earlier treatment settings. On its fourth quarter earnings call, Angela Hwang, group president of Pfizer Biopharmaceuticals said the hormone-sensitive prostate cancer patient population presents an sizable opportunity, with about 38,000 new patients per year and a longer duration of therapy.
Xtandi's main competitor now is Johnson & Johnson's Erleada (apalutatmide), the pharma's successor to its Zytiga (abiraterone acetate) franchise.
Erleada is currently approved only for non-metastatic castration-resistant prostate cancer, and J&J hopes that growing market share there will help make up for the loss of patent protection on Zytiga.
Zytiga brought in $3.5 billion in sales last year, a 40% increase from 2017, but now faces generic competition.
Xtandi is also being assessed in the Phase 3 EMBARK study for use in men with high-risk non-metastatic HSPC.