In crowded prostate cancer market, Pfizer's Xtandi notches third approval for use in earlier stage of disease
Pfizer’s entrenched androgen receptor inhibitor Xtandi has secured its third prostate cancer approval in a market flush with rivals.
On Monday, Pfizer and partner Astellas announced Xtandi had scored FDA approval in patients with metastatic castration (or hormone)-sensitive prostate cancer (mCSPC). It’s a form of prostate cancer that has spread to other parts of the body but still responds to a medical or surgical treatment that lowers testosterone — affecting roughly 40,000 men in the United States currently. Xtandi is now the only oral FDA-approved therapy in three distinct types of advanced prostate cancer, the companies said.
Xtandi in combination with standard androgen deprivation therapy (ADT) was tested against ADT plus placebo in the ARCHES trial in 1,150 patients with metastatic hormone (or castration) sensitive prostate cancer.
Data showed the Xtandi combination reduced the risk of radiographic progression or death by 61% versus placebo plus ADT (confidence interval: 0.30-0.50; p<0.0001) — overall survival data were not mature at the time of analysis.
In the first nine months of 2019, the drug generated $594 million in global sales. Anti-androgens drugs such as J&J’s Zytiga and Pfizer’s Xtandi were first approved in metastatic castration-resistant prostate cancer (mCRPC) in 2011 and 2012 respectively. Since then, this class of drugs has also shown to be effective in earlier-disease settings such as non-metastatic CRPC and metastatic hormone-sensitive prostate cancer (mHSPC).
In a note reflecting discussions by a panel of prostate cancer experts in September, Cowen analysts cited a panelist that indicated that the several anti-androgens on the market are on somewhat “equal footing” in the mHSPC setting with similar clinical data. “Patients in the U.S. prefer oral hormonal agents over alternative chemotherapy, so our expert believes Zytiga and Xtandi could both hold substantial market share in mHSPC,” they wrote.
Prostate cancer is the second most commonly diagnosed malignancy in men globally, and treatment options include surgery, radiation treatment and therapy using hormone-receptor antagonists. However, in nearly every case, the cancer grows resistant to conventional hormone therapy. Castration-resistant prostate cancer (CRPC) is an advanced form of the disease and is characterized by persistent, high-level androgen receptor (AR) function and resistance to conventional anti-androgens.
Earlier this year, Bayer and Finnish partner Orion’s AR inhibitor Nubeqa was approved for patients with castration-resistant prostate cancer that has not spread to other parts of the body (nmCRPC). Meanwhile, PARP and PD-(L)1 agents are also being tested for use in prostate cancer.
Social image: Pfizer, Jeff Rumens