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CDK4/6 Inhibitor Maintained OS Benefit in Advanced Breast Cancer

— Sayeh Lavasani discusses the latest updates from MONALEESA-3

MedpageToday

Ribociclib (Kisqali) plus fulvestrant (Faslodex) maintained significantly improved overall survival (OS) rates after nearly 5 years of follow-up compared with fulvestrant alone in postmenopausal patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer. The results of the were presented at the recent virtual American Society of Clinical Oncology (ASCO) annual meeting.

In this exclusive 51˶ video, , of the City of Hope Comprehensive Cancer Center in Duarte, California, breaks down the data from the updated analysis.

Following is a transcript of her remarks:

I want to talk about the updates for the MONALEESA-3 clinical trial that was presented at ASCO 2021 by Dennis Slamon, MD, PhD. So they actually presented overall survival results from this phase III study that was a randomized clinical trial of postmenopausal patients who had hormone receptor-positive, HER2-negative metastatic breast cancer, and they were treated with fulvestrant plus and minus ribociclib.

So in this study, they randomized 726 patients 2:1 to ribociclib plus fulvestrant versus placebo plus fulvestrant. And the primary endpoint in this study was progression-free survival. They had multiple secondary endpoints, including overall survival and overall response rate, and also safety. The overall survival in overall population showed that there was actually 53.7 months in the investigational arm -- patients who received ribociclib -- versus 41.5 months in patients who received placebo. There was a hazard ratio of 0.726.

The overall survival in patients treated in the first-line setting was 51.8 months in patients who received fulvestrant and placebo, and in patients who received ribociclib, they couldn't count it because the patients were still alive. And the overall survival in patients who were treated in the second line of therapy also showed improvement in patients who received ribociclib and fulvestrant versus placebo and fulvestrant. It had a hazard ratio of 0.78.

Overall, the conclusion of this study was that in the exploratory analysis with extended median follow-up of 56.3 months, which they presented at ASCO, ribociclib and fulvestrant maintained the overall survival benefit in postmenopausal patients with hormone receptor-positive, HER2-negative advanced breast cancer. And the benefit that was seen included all subgroups of patients and settings. For ribociclib and fulvestrant versus fulvestrant alone, the median overall survival was 53.7 months compared to 41.5 months. So there was actually more than 12 months' improvement in overall survival of patients who received ribociclib.

This remains the only randomized trial evaluating a CDK4/6 inhibitor, and showed overall survival benefit in postmenopausal patients who are treated in the first-line setting with this CDK4/6 inhibitor. And also this study showed that patients who received ribociclib and fulvestrant, there was a delay in the use of subsequent chemotherapy and these patients had prolonged chemotherapy-free survival compared to patients who did not receive ribociclib. So, in general, these patients also tolerated treatment very well, and there was no new toxicity that was observed in this study update.

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    Greg Laub is the Senior Director of Video and currently leads the video and podcast production teams.