Fulvestrant With or Without Venetoclax in Locally Advanced or Metastatic Breast Cancer
Posted: Wednesday, July 14, 2021
Patients with estrogen receptor–positive, HER2-negative, locally advanced or metastatic breast cancer are typically treated with CDK4/6 inhibitors and endocrine therapy as first-line treatment. Geoffrey J. Lindeman, FRACP, MBBS, PhD, of Peter MacCallum Cancer Centre/Walter and Eliza Hall Institute, Melbourne, and colleagues conducted the phase II VERONICA trial to determine whether adding the BCL2 inhibitor venetoclax to fulvestrant would improve outcomes over fulvestrant alone in this patient population. However, according to the findings presented during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1004), outcomes were not improved with this therapeutic strategy.
“From the primary analysis, VERONICA did not show an improved clinical benefit rate or progression-free survival with venetoclax plus fulvestrant versus fulvestrant alone, in patients with endocrine- and CDK4/6 inhibitor–refractory locally advanced/metastatic breast cancer,” the investigators stated.
Women with estrogen receptor–positive, HER2-negative locally advanced or metastatic breast cancer who had received at least two prior lines of endocrine therapy but no chemotherapy were enrolled (n = 103). Patients were also required to have experienced disease progression following CDK4/6 inhibitory therapy. Random assignment placed patients into groups that received either oral venetoclax (800 mg) plus intermittent intramuscular fulvestrant (500 mg) or fulvestrant alone.
The clinical benefit rate was seemingly not different between the groups at primary analysis, with a risk difference of just 1.96%. Similarly, the median progression-free survival appeared to be unaffected with the addition of venetoclax (2.69 months, 95% confidence interval [CI] = 1.94–3.71 months) compared with fulvestrant alone (1.94 months, 95% CI = 0.61–1.45 months). In addition, there did not appear to be differences across stratification. The median overall survival has not been reached in the fulvestrant group but was 17.0 months in the venetoclax-plus-fulvestrant group. The majority of grade 3 or 4 adverse events were observed in the group that received venetoclax (26.0%) compared with fulvestrant alone (11.8%). Biomarker analysis has not yet been completed but is ongoing.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.