Novel Treatment Strategies for Hormone Receptor (HR)-Positive, HER2-Negative Metastatic Breast Cancer.

Estrogen receptor (ER)-positive breast cancer (BC) is the most common BC subtype. Endocrine therapy (ET) targeting ER signaling still remains the mainstay treatment option for hormone receptor (HR)-positive BC either in the early or in advanced setting, including different strategies, such as the suppression of estrogen production or directly blocking the ER pathway through SERMs-selective estrogen receptor modulators-or SERDs-selective estrogen receptor degraders. Nevertheless, the development of de novo or acquired endocrine resistance still remains challenging for oncologists. The use of novel ET combined with targeted drugs, such as cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, has significantly improved long-term outcome rates, thus changing the therapeutic algorithm for metastatic BC (MBC) and recently the therapeutic strategy in the adjuvant setting for early high-risk BC. Eluding the resistance to CDK4/6 inhibitors combined with ET is currently an unmet medical need, and there is disagreement concerning the best course of action for patients who continue to progress after this combination approach. Genetic changes in the tumor along its growth uncovered by genomic profiling of recurrent and/or metastatic lesions through tumor and/or liquid biopsies may predict the response or resistance to specific agents, suggesting the best therapeutic strategy for each patient by targeting the altered ER-dependent pathway (novel oral SERDs and a new generation of anti-estrogen agents) or alternative ER-independent signaling pathways such as PI3K/AKT/mTOR or tyrosine kinase receptors (HER2 mutations or HER2 low status) or by inhibiting pathways weakened through germline BRCA1/2 mutations. These agents are being investigated as single molecules and in combination with other target therapies, offering promising weapons to overcome or avoid treatment failure and propose increasingly more personalized treatment approaches. This review presents novel insights into ET and other targeted therapies for managing metastatic HR+/HER2- BC by exploring potential strategies based on clinical evidence and genomic profiling following the failure of the CDK4/6i and ET combination.

Ribociclib-induced liver injury: a case report.

Background: Idiosyncratic drug-induced liver injury (DILI) is a rare, unpredictable hepatic adverse event and the most common cause of acute liver failure in Europe and the US. Ribociclib is a potent Cyclin-dependent kinase 4 and 6 (CDK4/6)-inhibitor administered for advanced hormone-receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Previous reports have shown hepatotoxicity without liver necrosis related to ribociclib. Case presentation: A 41-year-old female patient with primary metastatic HR-positive, HER2-negative breast cancer developed liver enzyme elevation under treatment with ribociclib. Ribociclib was withdrawn 8 weeks after initiation due to liver enzyme elevation. A liver biopsy, performed due to further enzyme increase (peak ALT 2836 U/l), onset of jaundice (peak bilirubin 353 µmol/l) and coagulopathy (INR 1.8) two weeks later, revealed acute hepatitis with 30% parenchymal necrosis. Roussel Uclaf Causality Assessment Method (RUCAM) score was 7 points (probable). Under treatment with prednisone (60mg), initiated 2 weeks after drug withdrawal, and subsequently N-acetylcysteine (Prescott regimen) liver enzymes normalized within 8 weeks along with prednisone tapering. Conclusion: This case illustrates the development of a severe idiosyncratic hepatocellular pattern DILI grade 3 (International DILI Expert Working Group) induced by ribociclib. Routine liver enzyme testing during therapy, immediate hepatologic work-up and treatment interruption in case of liver enzyme elevation are highly recommended. Corticosteroid treatment should be considered in cases of severe necroinflammation.

Patterns of treatment with everolimus exemestane in hormone receptor-positive HER2-negative metastatic breast cancer in the era of targeted therapy.

BACKGROUND: There is currently no clinical trial data regarding the efficacy of everolimus exemestane (EE) following prior treatment with CDK4/6 inhibitors (CDK4/6i). This study assesses the use and efficacy of everolimus exemestane in patients with metastatic HR+ HER2- breast cancer previously treated with endocrine therapy (ET) or endocrine therapy + CDK4/6i. METHODS: Retrospective analysis of electronic health record-derived data for HR+ HER2- metastatic breast cancer from 2012 to 2018. The proportion of patients receiving EE first-line, second-line, or third-line, and the median duration of EE prior to next line of treatment (TTNT) by line of therapy was calculated. OS for patients receiving EE first-line, second-line, or third-line, indexed to the date of first-line therapy initiation and stratified by prior treatment received, was calculated with Kaplan-Meier method with multivariable Cox proportional hazards regression analysis. RESULTS: Six hundred twenty-two patients received EE first-line (n = 104, 16.7%), second-line (n = 273, 43.9%) or third-line (n = 245, 39.4%). Median TTNT was 8.3 months, 5.5 months, and 4.8 months respectively. Median TTNT of EE second-line was longer following prior ET alone compared to prior ET + CDK4/6i (6.2 months (95% CI 5.2, 7.3) vs 4.3 months (95% CI 3.2, 5.7) respectively, p = 0.03). Similarly, EE third-line following ET alone vs ET + CDK4/6i in first- or second-line resulted in median TTNT 5.6 months (95% CI 4.4, 6.9) vs 4.1 months (95% CI 3.6, 6.1) respectively, although this was not statistically significant (p = 0.08). Median OS was longer for patients who received EE following prior ET + CDK4/6i. EE second-line following ET + CDK 4/6i vs ET alone resulted in median OS 37.7 months vs. 32.7 months (p = 0.449). EE third-line following ET + CDK4/6i vs prior ET alone resulted in median OS 59.2 months vs. 40.8 months (p < 0.010). This difference in OS was not statistically significant when indexed to the start of EE therapy. CONCLUSION: This study suggests that EE remains an effective treatment option after prior ET or ET + CDK4/6i use. Median TTNT of EE was longer for patients who received prior ET, whereas median OS was longer for patients who received prior ET + CDK4/6i. However, this improvement in OS was not statistically significant when indexed to the start of EE therapy suggesting that OS benefit is primarily driven by prior CDK4/6i use. EE remains an effective treatment option regardless of prior treatment option.