Do you have Metastatic ER+/HER2− Breast Cancer with an ESR1 Mutation?

Primary Objectives

To evaluate the progression free survival (PFS) of the combination of lasofoxifene and abemaciclib compared to fulvestrant and abemaciclib for the treatment of pre- and postmenopausal women and men who have previously received ribociclib or palbociclib-based treatment and have locally advanced or metastatic estrogen receptor positive (ER+)/human epidermal growth factor 2 negative (HER2)− breast cancer with an estrogen receptor 1 (ESR1) mutation.

Secondary Objectives

To evaluate the antitumor response of each drug regimen as characterized by:
• Objective response rate (ORR)
• Overall survival (OS)
• Clinical benefit rate (CBR)
• Duration of response (DoR) in subjects with an objective response
• Time to response (TTR) in subjects with an objective response
In addition, to determine the following for the study population:
• Time to cytotoxic chemotherapy
• Quality of life (QoL) using Functional Assessment of Cancer Therapy-Breast Cancer-Endocrine Subscale (FACT B-ES) 
• Safety