In a presented at the American Society of Clinical Oncology annual meeting, researchers compared abemaciclib (Verzenio) plus fulvestrant (Faslodex) versus fulvestrant plus placebo in patients with hormone receptor-positive, HER2-negative advanced breast cancer following progression on a prior CDK4/6 inhibitor plus endocrine therapy.
In this exclusive Ƶ video, Joanne Mortimer, MD, from City of Hope in Duarte, California, talked about the study, which showed improved progression-free survival with the addition of abemaciclib, supporting the continued use of CDK4/6 inhibitors in this setting.
Following is a transcript of her remarks:
This was a study that tried to validate the role of continuing CDK4/6 inhibitors as second-line therapy in individuals who had been treated with first-line CDK4/6 inhibitors and endocrine therapy for first-line metastatic breast cancer.
So, [this] was a randomized placebo-controlled trial that compared single-agent Faslodex versus Faslodex -- fulvestrant -- with abemaciclib. And the conclusion of the study was that progression-free survival favored the addition of abemaciclib or the continuation of a CDK4/6 inhibitor with fulvestrant in a second-line therapy. This is particularly interesting because they also had next-gen sequencing from Guardant on 85% of the patients, and there was no difference in outcome regardless of PIK3CA or ESR1 mutations.
It's a very interesting study and seems to support the continuation of a CDK4/6 inhibitor like abemaciclib. However, I would be somewhat concerned that the majority of the patients' first-line therapy was with palbociclib [Ibrance], and palbociclib is recognized as being perhaps inferior to ribociclib [Kisqali] and abemaciclib, as there is no prolongation in overall survival. So whether these data will hold up when first-line therapy is ribociclib followed by abemaciclib, I think really does need to be shown.
But these data are very interesting and do seem to support a previously published trial, MAINTAIN, that looked at the same combination of endocrine therapy with addition of a CDK4/6 inhibitor, in this case ribociclib, and support those results of continuing a CDK4/6 inhibitor.