ASCO 2021: Long-Term Survival With Palbociclib Plus Fulvestrant in Advanced Breast Cancer
Posted: Thursday, June 24, 2021
Massimo Cristofanilli, MD, of Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, and colleagues presented their updated analyses from PALOMA-3—a double-blind, placebo-controlled phase III study of palbociclib plus fulvestrant in women with hormone receptor (HR)-positive/HER2-negative breast cancer—during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1000). These investigators reported a “clinically meaningful” improvement in overall survival maintained for more than 6 years of median follow-up.
“This combination therapy remains the most effective treatment we have for hormone receptor–positive metastatic breast cancer,” stated Dr. Cristofanilli in an interview with The ASCO Post.
This trial focused on 521 patients with HR-positive/HER2-negative advanced breast cancer who experienced disease progression on previous endocrine therapy. Participants were randomly assigned 2:1 to receive 500 mg of fulvestrant plus 125 mg of palbociclib or placebo.
With a previous median overall survival of 34.9 months and 28.0 months for the palbociclib and placebo groups (hazard ratio [HR] = 0.814), respectively, overall survival was reported to continue to improve with longer follow-up. In the palbociclib arm, the 5-year overall survival rate was 23.3%, whereas the rate in the placebo arm was 16.8% (HR = 0.806). Most subgroups demonstrated a favorable overall survival in the palbociclib-plus-fulvestrant group versus the placebo-plus-fulvestrant group, excluding individuals who had prior chemotherapy or were endocrine-resistant.
Although no additional safety signals were identified, 15 and 3 patients remain on palbociclib plus fulvestrant and placebo plus fulvestrant, respectively. For 20 patients given palbociclib and 32 patients given placebo, a post-study CDK4/6 inhibitor was administered.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
