Combination therapy with a cyclin-dependent kinase (CDK) 4/6 inhibitor and an aromatase inhibitor (AI) has the same good efficacy but greater toxicity in women with hormone receptor (HR)–positive, HER2-negative advanced breast cancer who are aged 75 years or older, a pooled analysis of randomized controlled trials concluded.
Results reported in the Journal of Clinical Oncology showed that in this age-group, compared with an AI alone, the combination of a CDK 4/6 inhibitor with an AI reduced the risk of progression or death by 51%, similar to the 44% reduction seen among women younger than 75 years. At the same time, nearly 9 in 10 of the older group experienced grade 3 or 4 adverse events, relative to roughly 7 in 10 of the younger group.
“Compared with their younger counterparts, older patients derived similar benefit from treatment with a CDK4/6 inhibitor, worsened toxicity that could be managed with supportive care, and similar decline in quality-of-life measures regardless of the addition of a CDK4/6 inhibitor,” summarized Harpreet Singh, MD, a medical officer at the Food and Drug Administration and coinvestigators.
“As CDK4/6 inhibitors are incorporated into the standard of care for the initial treatment of HR-positive, HER2-negative MBC [metastatic breast cancer], this pooled analysis provides important efficacy, safety, and tolerability data for counseling older women who are considering use of AIs in combination with CDK4/6 inhibitors,” they wrote.