Breast Cancer Coverage from Every Angle

Update on CDK4/6 and Aromatase Inhibitors in Older Women With Breast Cancer

By: Sylvia O'Regan
Posted: Wednesday, November 6, 2019

In the first-line setting, a combination of a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor and an aromatase inhibitor is similarly effective as an aromatase inhibitor alone in older women compared with younger women with HER2-negative, hormone receptor–positive metastatic breast cancer. However, women older than age 75 did experience higher rates of toxicity, dose modifications, and decrease from baseline in quality-of-life measures. The findings of this pooled analysis were published in the Journal of Clinical Oncology by Lynn J. Howie, MD, of the U.S. Food and Drug Administration, and colleagues.

The investigators examined data from three controlled studies—PALOMA-2, MONALEESA-2, AND MONARCH 3—looking at the use of different CDK4/6 inhibitors with an aromatase inhibitor in the treatment of more than 1,000 postmenopausal women with metastatic breast cancer. Of the total study population, 456 women (25%) were 70 years of age or older.

“There was similar efficacy with a CDK4/6 inhibitor in combination with an aromatase inhibitor compared with an aromatase inhibitor alone for first-line treatment of hormone receptor–positive, HER2-negative metastatic breast cancer in older women compared with younger patients,” the investigators reported. For patients older than age 70 who received the combination treatment, the estimated median progression-free survival was 33.1 months, compared with 19.2 months for those who received an aromatase inhibitor alone. In addition, a breakdown of the results showed that patients aged 75 years and older who were treated with a CDK4/6 inhibitor and an aromatase inhibitor had an estimated median progression-free survival of 31.1 months versus 13.7 months for those treated with an aromatase inhibitor alone.

Of the 1,105 patients who received at least one dose of a CDK4/6 inhibitor included in the safety population, a higher rate of grade 3 or 4 adverse events was reported in those 75 years or age and older than in those younger than age 75 (88.8% versus 73.4%). In addition, more than half of patients aged 70 and older required at least two dose reductions or interruptions.

Disclosure: The study authors’ disclosure information may be found at

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