Adding orteronel to androgen deprivation therapy (ADT) does not improve overall survival (OS) in patients with metastatic, hormone-sensitive prostate cancer (mHSPC), according to research published in the Journal of Clinical Oncology.

In a phase 3 trial, OS outcomes were similar for patients who received orteronel plus ADT and those who received bicalutamide plus ADT. However, patients who received orterone had an improvement in progression-free survival (PFS) and prostate-specific antigen (PSA) response.

The trial (ClinicalTrials.gov Identifier: NCT01809691) included 1279 patients with mHSPC — 638 who were randomly assigned to the orteronel arm and 641 to the bicalutamide arm. At baseline, most patients had bone metastases — 74% in the orteronel arm and 75% in the bicalutamide arm. The median age was 67.6 years and 68.1 years, respectively, and the median PSA level was 27.2 ng/mL and 31.8 ng/mL, respectively.


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At a median follow-up of 4.9 years, there was no improvement in OS with orteronel. The median OS was 81.1 months in the orteronel arm and 70.2 months in the bicalutamide arm (hazard ratio [HR], 0.86; 95% CI, 0.72-1.02; P =.04). The 5-year OS rate was 59.7% and 57.9%, respectively. 

The researchers noted that patients in the bicalutamide arm were more likely to receive post-protocol life-prolonging therapy than patients in the orteronel arm — 77.4% and 61.3%, respectively.

Patients in the orteronel arm had a significant improvement in PFS. The median PFS was 47.6 months in the orteronel arm and 23.0 months in the bicalutamide arm (HR, 0.58; 95% CI, 0.51-0.67; P <.001). 

Patients in the orteronel arm also had a significant improvement in PSA response at 7 months (P <.0001). The complete response rate was 58% with orteronel and 44% with bicalutamide.

“The lack of correlation of PFS and PSA response with OS raises concerns over assumption of their consistent surrogacy for OS in the context of extensive post-protocol therapy in this setting,” the researchers wrote.

“These results indicate that orteronel is likely not an effective androgen axis inhibitor compared with recently approved agents in this setting. Higher than anticipated OS of patients in the control arm is reflective of therapeutic advancements made over the past decade in men with metastatic prostate cancer.”

The researchers also found that grade 3 to 4 adverse events were more common in the orteronel arm than in the bicalutamide arm — 43% and 13%, respectively. 

Disclosures: This research was supported, in part, by Millennium Pharmaceuticals. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.  

Reference

Agarwal N, Tangen CM, Hussain MHA, et al. Orteronel for metastatic hormone-sensitive prostate cancer: A multicenter, randomized, open-label phase III trial (SWOG-1216). J Clin Oncol. Published online April 21, 2022. doi:10.1200/JCO.21.02517

This article originally appeared on Cancer Therapy Advisor