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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Friday, March 11, 2022
According to research presented in JAMA Oncology, letrozole appears to be the optimal endocrine partner for the CDK4/6 inhibitor palbociclib versus the antiestrogen agent fulvestrant among patients with endocrine-sensitive, hormone receptor–positive, ERBB2-negative advanced breast cancer. The international phase II study known as PARSIFAL assessed survival outcomes associated with letrozole versus fulvestrant among this patient population.
“Despite the significant antitumor activity of fulvestrant-palbociclib, this combination showed no superiority in progression-free survival over the standard letrozole-palbociclib in this patient population,” noted Javier Cortés, MD, of Medica Scientia Innovation Research, Barcelona, and colleagues.
Between July 30, 2015, and January 8, 2018, the study enrolled 486 women with hormone receptor–positive, ERBB2-negative advanced breast cancer. Most participants (94.9%) were White; the average patient age was 63 years. Patients received palbociclib with either fulvestrant or letrozole.
Median progression-free survival was superior in the letrozole group, reaching 32.8 months versus 27.9 months in the fulvestrant group. According to the investigators, the benefit did not appear to be impacted by stratification factors such as disease presentation type or the presence of visceral involvement.
The rates of objective response and 3-year overall survival were comparable between fulvestrant and letrozole groups (46.5% vs. 50.2% and 79.4% vs. 77.1%, respectively). No significant difference was observed in grade 3 or 4 adverse events. No new safety signals or treatment-related deaths were recorded.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.
