Real-world effectiveness of everolimus-based therapy versus fulvestrant monotherapy in HR(+)/HER2(-) metastatic breast cancer

Outcome of Everolimus-Based Therapy in Hormone-Receptor-Positive Metastatic Breast Cancer Patients After Progression on Palbociclib

Background

Despite the approval of mTOR inhibitor everolimus and CDK4/6 inhibitors in the management of hormone-receptor-positive HER2 non-amplified metastatic breast cancer (HR+ HER2-MBC), the optimal sequence of therapy is unclear. There are no clinical data on efficacy of everolimus in HR+ HER2-MBC after cancer progresses on CDK4/6 inhibitors.

Objective

The objective of this study is to find the efficacy of everolimus in HR+ HER2-MBC after they progress on a CDK4/6 inhibitor palbociclib.

Methods

This is a retrospective, 2-institute review of HR+ HER2-MBC from Jan 2015 to March 2018 treated with everolimus after progression on palbociclib. Primary end point was median progression-free survival (PFS), secondary end points objective response rate (ORR), clinical benefit ratio (CBR), and overall survival (OS).

Results

Out of 41 women with median age 61 years (33, 87) enrolled, 66% had received adjuvant systemic therapy, 61% had visceral disease, and 95% had prior nonsteroidal aromatase inhibitors. About 83% women had 3 or more chemotherapy or hormonal therapies prior to everolimus. Kaplan-Meier estimates showed a median PFS of 4.2 months (95% confidence interval [CI]: 3.2-6.2). The median OS was 18.7 months (95% CI 9.5 to not reached). Objective response rate and CBR were both 17.1%.

Conclusion

Everolimus was associated with modest PFS and ORR in HR+ HER2-MBCs postprogression on palbociclib.

Role of everolimus in the treatment of metastatic HER2-negative/HR-positive breast cancer

Metastatic breast cancer (mBC) is a leading cause of mortality for women around the world. The response to hormonotherapy of the patients with HER2-negative/HR-positive mBC is usually limited, and many strategies are in place to contrast the hormonotherapy resistance. Since efficacy and effectiveness of everolimus have been established by many trials, this review is aimed to give a structured synthesis to define the everolimus clinical role among the treatment options for mBC. Key aspects of everolimus dosing and safety profile, drawn up by relevant findings, are included, as well as the role of biomarkers to identify subgroups of mBC patients who may best benefit from everolimus treatment.