Longer Follow-Up of MONALEESA-3 Shows Subgroup Efficacy and Safety

Dennis J. Slamon, MD, PhD, director of the Revlon/UCLA Women's Cancer Research Program at Johnson Comprehensive Cancer Center; a professor of medicine; chief of the Division of Hematology/Oncology; executive vice chair of research in the Department of Medicine; and director of clinical/translational research at The University of California, Los Angeles, discusses the subgroup benefits and safety profile of ribociclib (Kisqali) plus fulvestrant (Faslodex) in patients with hormone receptor-positive, HER2-negative advanced breast cancer.

All of the subgroups on the phase 3 MONALEESA-3 trial benefited from treatment with ribociclib and fulvestrant, according to Slamon. Additionally, the toxicity profile did not demonstrate any new safety signals or significant differences between the 2 arms.

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0:08: When you do a subgroup analysis, and basically look at a forest plot, almost all groups benefited with ribociclib, whether they had got the treatment in the first line or the second line. Even patients with liver and lung involvement had a benefit. And these are patients who have among the worst prognosis; patients with bone-only disease, yes or no, either group had the significant benefit. Whether there was more or less than 3 metastatic sites; whether the patients were less than 65, or older than 65; whether they gotten their therapy in the adjuvant or neoadjuvant setting; or whether they got their most recent therapy in the metastatic setting; essentially all groups benefited.

1:02: That really speaks, I think, to the importance of using these drugs in this patient population when you first diagnose the disease, even if it’s the first line setting. The other thing the MONALEESA studies in general have shown is even in adjuvant therapy in premenopausal patients in MONALEESA-7, we're seeing the same kind of benefit in terms of progression-free survival and overall survival. So all in all, I think it's a compelling story.

1:38: So we did look at the safety. There was absolutely no new safety signals. It was the anticipated class effect of neutropenia [and] leukopenia that we see with all of the inhibitors, in particular with palbociclib and ribociclib, but a little less so with abemaciclib. But then abemaciclib has more gastrointestinal toxicity that you don't see with ribociclib or palbociclib. The QTc prolongation was also seen, that we see with ribociclib. We don't see that so much with palbociclib or abemaciclib, but there were no significant increases in that and there was no torsades or any problem with the numbers in QTc prolongation overall. All grades were 8.5% versus 2.1%, and for grade 3 or grade 4, it was 2.9% versus 1.2%. So it wasn't a big difference between the 2 arm but there was a difference that should be noted. And I think otherwise, everything looked exactly like we saw in the initial analysis of the studies.