Enzalutamide Plus ADT Improves Time to PSA Progression in mHSPC

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The phase 3 China ARCHES trial (NCT04076059) met its primary end point of improvement in time to prostate-specific antigen (PSA) progression (TTPP) in Chinese patients with metastatic hormone-sensitive prostate cancer (mHSPC), according to a press release from Astellas Pharma Inc.¹

The multi-center double-blind placebo-controlled study showed that enzalutamide (Xtandi) plus androgen deprivation therapy (ADT) demonstrated a statistically significant improvement in TTPP versus placebo plus ADT in Chinese patients. This confirms the outcomes of the global phase 3 ARCHES trial (NCT02677896) in this patient population.

“With the rising incidence of prostate cancer diagnoses among men in China, there is a need for new and effective treatment options," Ahsan Arozullah, MD, MPH, senior vice president and head of development therapeutic areas for Astellas, said in the press release. “As observed in our global phase 3 ARCHES study, and now reaffirmed with China ARCHES, [enzalutamide] significantly delays the time to disease progression in men with mHSPC and may provide an important treatment option for men in China if approved.”

Although it has not been approved by China’s National Medical Products Administration (NMPA), enzalutamide plus ADT was approved in the United States for patients with metastatic castration-sensitive prostate cancer in 2019 following the publication of results from the ARCHES trial.²

In ARCHES, the primary end point was radiographical progression-free survival (rPFS), which was not reached (NR) in the enzalutamide arm versus 19.4 months (95% CI: 16.6, NR) in the placebo arm (HR, 0.39; 95% CI, 0.30-0.50; P < .0001) at the time of FDA approval. In the primary analysis of the ARCHES trial, the TTPP was not reached for either arm, with a HR strongly favoring enzalutamide (HR, 0.19; 95% CI, 0.13-0.26, P < .001).³

The China ARCHES trial enrolled approximately 180 patients with mHSPC who were randomly assigned on a 1:1 basis to receive enzalutamide once daily with ADT via bilateral orchiectomy or luteinizing hormone-releasing hormone agonist/antagonist, or ADT with an oral placebo. The primary end point of TTPP was defined as at least a 25% increase and an absolute increase of at least 2 ng/mL above the nadir, confirmed by a second consecutive value at least 3 weeks later. Secondary end points include rPFS, percentage of patients with a PSA response, time to initiation of new antineoplastic therapy, PSA undetectable rate, and objective response rate.

In addition to demonstrating superior TTPP, it was reported that in China ARCHES, enzalutamide plus ADT also showed benefit over placebo plus ADT for the secondary end points of rPFS and rate of undetectable PSA.¹

"While past global studies have supported the use of [enzalutamide] plus ADT in men with mHSPC, it is encouraging to see these results replicated for patients in mainland China," Zhou Fangjian, MD, head of urology department, Sun Yat-sen University Cancer Center, Guangzhou, China, stated in the press release.¹

Detailed results from the trial will be submitted for publication soon, and they will be shared with the NMPA to potentially support a filing for approved use in China.

“As an existing standard of care for Chinese men with castration-resistant prostate cancer, enzalutamide has the potential to help men earlier in their treatment journey – before their disease stops responding to therapies that lower testosterone,” Dingwei Ye, MD, PhD, vice president of the Fudan University Shanghai Cancer Center, Director of the Multi-disciplinary Team for GU Cancer, stated in the press release.

_REFERENCES

_{1. Astellas Announces Phase 3 China ARCHES Study of XTANDI® Meets Primary Endpoint. News release. Astellas Pharma Inc. March 13, 2023. Accessed March 15, 2023. https://bit.ly/3JHLZ79}

_{2. FDA approves enzalutamide for metastatic castration-sensitive prostate cancer. FDA. December 16, 2019. Accessed March 15, 2023. https://bit.ly/3YQm6q0}

_{3. Armstrong AJ, Szmulewitz RZ, Petrylak DP, et al. ARCHES: A randomized, phase III study of androgen deprivation therapy with enzalutamide or placebo in men with metastatic hormone-sensitive prostate cancer. J Clin Oncol. 2019;37(32):2974-2986. doi:10.1200/JCO.19.00799}