Survival Outcomes With Palbociclib and Fulvestrant in Breast Cancer
Posted: Wednesday, February 27, 2019
According to research published in The New England Journal of Medicine, the addition of the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor palbociclib to fulvestrant therapy improved survival in patients with hormone receptor–positive, HER2-negative advanced breast cancer who had sensitivity to prior endocrine therapy. However, the overall survival benefit with the combination therapy was not statistically significant in the entire trial population.
“A planned subgroup analysis of overall survival regarding the three prespecified stratification factors identified the patients who derived the most benefit from palbociclib,” concluded Nicholas C. Turner, MD, of the Institute of Cancer Research and Royal Marsden Hospital in London, and colleagues. The prespecified stratification factors were the presence or absence of sensitivity to endocrine therapy, the presence or absence of visceral metastatic disease, and menopausal status.
The phase III PALOMA-3 trial included 521 patients with breast cancer who had experienced relapse or disease progression during previous endocrine therapy. Participants were assigned 2:1 to receive either palbociclib/fulvestrant (n = 347) or placebo/fulvestrant (n = 174).
At a median follow-up of 44.8 months, the median overall survival among all 521 participants was 34.9 months with palbociclib and 28.0 months without. Among 410 patients with sensitivity to previous endocrine therapy, the median overall survival was 39.7 months in the palbociclib/fulvestrant cohort and 29.7 months in the placebo/fulvestrant cohort.
A total of 16% of patients in the placebo/fulvestrant group received CDK4/6 inhibitor treatment after the completion of the trial. Both the palbociclib/fulvestrant and placebo/fulvestrant cohorts experienced a similar median duration of subsequent therapy, although the median time to chemotherapy was 17.6 months for the former and 8.8 months for the latter. No new safety signals were noted during the follow-up period.
Disclosure: The study authors’ disclosure information may be found at nejm.org.