Enzalutamide demonstrated clinical activity among patients with advanced androgen receptor (AR)-expressing triple-negative breast cancer (TNBC), according to a study published in the Journal of Clinical Oncology.1
For this prospective phase 2 study (ClinicalTrials.gov Identifier: NCT01889238), investigators assessed the outcomes of 118 patients with AR-positive locally advanced or metastatic TNBC who received enzalutamide 160 mg once daily.
Of the 118 patients enrolled, 78 were evaluable at the time of analysis. The clinical benefit rates (CBRs) at 16 weeks were 25% (95% CI, 17%-33%) and 33% (95% CI, 23%-45%) among the 118 patients in the ITT population and patients in the evaluable subgroup, respectively.
The ITT population had a median progression-free survival (PFS) of 2.9 months (95% CI, 1.9-3.7) vs 3.3 months (95% CI, 1.9-4.1) in the evaluable subgroup. The median overall survival (OS) was 12.7 months (95% CI, 8.5-not evaluable) vs 17.6 months (95% CI, 11.6-not evaluable) in the ITT population vs the evaluable subgroup, respectively.
The most frequently reported adverse events (AEs) included headache, muscular weakness, pleural effusion, metastatic pain, anxiety, and general physical deterioration. The only grade 3 or worse AE occurring in more than 2% of patients was fatigue.
The authors concluded that the results “from this phase II study in a group of patients with AR-positive TNBC support and build upon the findings from others that there seems to exist a subset of patients with androgen-driven TNBC who may benefit from an AR-targeted agent.”
- Traina TA, Miller K, Yardley DA, et al. Enzalutamide for the treatment of androgen receptor-expressing triple-negative breast cancer. J Clin Oncol. 2018 Jan 26. doi: 10.1200/JCO.2016.71.3495 [Epub ahead of print]