Pfizer and Astellas Boost Xtandi's Potential in Early-Stage Prostate Cancer

Pfizer and Astellas have strengthened the case for Xtandi (enzalutamide) in the treatment of early-stage prostate cancer, following positive overall survival results from their phase 3 Embark study. The trial, which focused on non-metastatic hormone-sensitive prostate cancer (nmHSPC) patients with high-risk biochemical recurrence (BCR), has yielded mixed but promising outcomes for the drug's efficacy both as a monotherapy and in combination with leuprolide.

Xtandi Combination Therapy Shows Significant Survival Benefit

The Embark study's latest data reveal that Xtandi, when combined with leuprolide, demonstrated a "statistically significant and clinically meaningful improvement" in overall survival for nmHSPC patients. This achievement positions the Xtandi regimen as the first and only androgen receptor inhibitor-based treatment to show an overall survival benefit in this specific patient group.

Dr. Johanna Bendell, Pfizer's oncology chief development officer, emphasized the importance of these findings, stating, "These positive results add to the robust clinical support for the use of Xtandi and broaden clinical confidence, offering men with high-risk BCR evidence that they might live longer when they start Xtandi early."

Mixed Results for Xtandi Monotherapy

While the combination therapy showed significant promise, Xtandi as a monotherapy did not reach statistical significance in terms of overall survival. This outcome highlights the complexity of treating early-stage prostate cancer and underscores the potential benefits of combination approaches in certain patient populations.

The Embark study had previously met its primary endpoint, demonstrating a statistically significant improvement in metastasis-free survival for the Xtandi-leuprolide combination compared to placebo and leuprolide. These latest overall survival data further solidify the drug's efficacy profile in early-stage prostate cancer treatment.

Implications for Prostate Cancer Treatment Landscape

The positive results from the Embark study have significant implications for the treatment of prostate cancer, particularly for patients with high-risk BCR. An estimated 20% to 40% of men who have been treated for prostate cancer experience BCR within 10 years, with approximately 9 out of 10 men with high-risk BCR developing metastatic disease.

Xtandi's latest data could potentially influence treatment protocols for these patients, offering a new option that may delay disease progression and improve overall survival. The drug, first approved in 2012 for late-stage castration-resistant prostate cancer, has seen several expansions in its indications, with the 2023 approval marking its move into earlier prostate cancer treatment settings.