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Combo Promising in Metastatic, ESR1-Mutated Breast Cancer

— Lasofoxifene plus abemaciclib elicited encouraging PFS with an acceptable toxicity profile

MedpageToday

Novel lasofoxifene combined with abemaciclib (Verzenio) produced encouraging progression-free survival (PFS) along with acceptable toxicity in pretreated, locally advanced or metastatic breast cancer patients harboring an ESR1 mutation, according to findings of the .

In this exclusive 51˶ video, , of the Cleveland Clinic Comprehensive Cancer Center in Ohio, describes the phase II results presented at the in Chicago.

Following is a transcript of her remarks:

The ELAINE 2 trial is an open-label phase II study in women with hormone receptor-positive, HER2-negative ESR [estrogen receptor] mutant breast cancer that is metastatic or unresectable. And in this study, a combination of a novel selective estrogen receptor modulator called lasofoxifene was combined with abemaciclib, a CDK4/6 inhibitor, in women who had received prior therapy for their advanced disease.

The study was primarily looking at safety, but also evaluating efficacy in a relatively small cohort of patients. The combination of lasofoxifene and abemaciclib was found to be safe, with toxicities largely what one would expect from abemaciclib, with some nausea, diarrhea, cytopenias. And there were two cases of thrombosis in the population as well. But overall the combination was found to be safe.

And then the efficacy data was what was really exciting. So in this small study, they found a very impressive progression-free survival, a median of about 13.9 months. And this is a very high risk population with an ESR1 mutation. And most of the patients had received prior CDK4/6 inhibitors. Many had received prior chemotherapy. And all had received one or two lines, at least of prior endocrine therapy.

So we are very pleased to see those results. About two-thirds of the patients experienced clinical benefit, meaning they were free of progression at 24 weeks.

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