Treatment after Progression on Fulvestrant among Metastatic Breast Cancer Patients in Clinical Practice: a Multicenter, Retrospective Study

Targeting metabolic adaptations in the breast cancer-liver metastatic niche using dietary approaches to improve endocrine therapy efficacy

Estrogen receptor-positive (ER+) metastatic tumors contribute to nearly 70% of breast cancer-related deaths. Most patients with ER+ metastatic breast cancer (MBC) undergo treatment with the estrogen receptor antagonist fulvestrant (Fulv) as standard-of-care. Yet, among such patients, metastasis in the liver is associated with reduced overall survival compared to other metastasis sites. The factors underlying the reduced responsiveness of liver metastases to ER-targeting agents remain unknown, impeding the development of more effective treatment approaches to improve outcomes for patients with ER+ liver metastases. We therefore evaluated site-specific changes in MBC cells and determined the mechanisms through which the liver metastatic niche specifically influences ER+ tumor metabolism and drug resistance. We characterized ER activity of MBC cells both in vitro, using a novel system of tissue-specific extracellular matrix hydrogels representing the stroma of ER+ tumor metastatic sites (liver, lung and bone), and in vivo, in liver and lung metastasis mouse models. ER+ metastatic liver tumors and MBC cells grown in liver hydrogels displayed upregulated expression of glucose metabolism enzymes in response to Fulv. Furthermore, differential ERα activity, but not expression, was detected in liver hydrogels. In vivo, increased glucose metabolism led to increased glycogen deposition in liver metastatic tumors, while a fasting-mimicking diet increased efficacy of Fulv treatment to reduce the metastatic burden. Our findings identify a novel mechanism of endocrine resistance driven by the liver tumor microenvironment. Implications: These results may guide the development of dietary strategies to circumvent drug resistance in liver metastasis, with potential applicability in other metastatic diseases.

Safety and efficacy of everolimus (EVE) plus exemestane (EXE) in postmenopausal women with locally advanced or metastatic breast cancer: final results from EVEREXES

BACKGROUND

This study was conducted to collect clinical safety, tolerability, and efficacy data with the use of everolimus (EVE) combined with exemestane (EXE) in patients with advanced breast cancer (ABC).

METHODS

The EVEREXES trial initiated in 2012, provided early access to the first dual blockade treatment with EVE + EXE in patients with HR+, HER2 - ABC in Asia and other emerging growth countries. Postmenopausal women with HR+, HER2 - ABC who had documented recurrence or progression, following a nonsteroidal aromatase inhibitor therapy, were treated with EVE (10 mg/day) + EXE (25 mg/day) orally.

RESULTS

A total of 235 patients received ≥ 1 dose of study medication. At the end of the study, all patients ceased the treatment. Disease progression (66.0%) was the primary reason of discontinuation. The most common AEs (≥ 20%) were stomatitis, decreased appetite, hyperglycemia, rash, aspartate aminotransferase increased, anemia, alanine aminotransferase increased, cough, and fatigue. No new safety concerns were identified in the current study. Median progression-free survival (PFS) in the Asian subset was similar to that of the overall population (9.3 months in both groups). Confirmed overall response rate (ORR) was achieved for 19.6% of the patients. Efficacy of EVE + EXE across subgroups (prior CT, line of treatment, and presence of visceral metastases) was maintained.

CONCLUSION

The safety and efficacy results from EVEREXES trial are consistent to data previously reported in BOLERO-2. These results support that EVE + EXE could be a viable treatment option for the postmenopausal women with HR+, HER2 - ABC in Asian region.