Xtandi Shows 33% Reduction in Death Risk in Phase 3 Trial for Metastatic Hormone-Sensitive Prostate Cancer

Pfizer and Astellas’ Xtandi is seeking approval for prostate cancer indications. At the ASCO Annual Meeting, researchers presented study results on the drug’s use in metastatic hormone-sensitive prostate cancer: compared with other non-steroidal antiandrogens, Xtandi reduced the risk of death by 33%.

Xtandi, jointly developed and marketed by Astellas and Medivation, a Pfizer company, is a novel, once-daily oral androgen receptor signaling inhibitor. It inhibits multiple steps in the androgen receptor signaling pathway, aiming to interfere with the ability of testosterone to bind to prostate cancer cells. The drug has been proven to reduce cancer cell growth and induce tumor cell death. In the Phase 3 clinical trial named ENZAMET, Xtandi effectively extended the survival of patients with metastatic hormone-sensitive prostate cancer.

This large-scale study enrolled a total of 1,125 patients with metastatic hormone-sensitive prostate cancer, who were divided into two groups: one group received treatment with testosterone suppression therapy plus Xtandi, while the other group received testosterone suppression therapy plus other nonsteroidal antiandrogen drugs.

The study results indicated that the 3-year survival rate for patients in the Xtandi group was 80%, superior to the 72% observed in the control group. Collectively, this corresponds to a 33% reduction in the risk of death. Xtandi offers new therapeutic hope for specific male patients, meaning that treatment not only prolongs survival but also mitigates the side effects associated with chemotherapy.

In December 2018, Pfizer and Astellas announced that the Phase III clinical trial ARCHES (NCT02677896), evaluating the targeted anticancer drug Xtandi in combination with androgen deprivation therapy (ADT) for the treatment of patients with metastatic hormone-sensitive prostate cancer, had met its primary endpoint. Preliminary safety analysis showed that the safety profile of Xtandi was consistent with previous clinical studies conducted in patients with castration-resistant prostate cancer. These new trial data provide further support for the drug’s eventual regulatory approval.

Although Xtandi is currently approved for metastatic and non-metastatic castration-resistant prostate cancer, there remains an unmet need for additional treatment options in men with metastatic hormone-sensitive prostate cancer. The known positive top-line data demonstrate Xtandi’s potential to help male patients with prostate cancer whose disease has spread beyond the prostate but still responds to testosterone-lowering therapy.

The market competition for prostate cancer drugs has always been fierce, primarily involving Xtandi as well as Johnson & Johnson’s Zytiga and Erleada. In 2017, global sales of Xtandi reached $2.654 billion. In the first quarter of 2019, Xtandi’s sales amounted to $168 million, falling short of Wall Street’s previous forecast of $186 million.

However, since its approval in 2012, more than 330,000 male patients worldwide have received treatment with Xtandi. According to EvaluatePharma’s forecasts, global sales of Xtandi are expected to reach $4.467 billion in 2024, positioning the drug as a potential blockbuster in the field of prostate cancer therapy. (Compiled by Fan Dongdong for Sina Medicine)

Reference:

1、ASCO: Pfizer, Astellas' Xtandi racks up more data for new prostate cancer approval

2、Survival Improved at 3 Years With Enzalutamide Versus Other Anti-Androgens in mHSPC