Entinostat, a class I selective histone deacetylase inhibitor, plus exemestane for Chinese patients with hormone receptor-positive advanced breast cancer: A multicenter, randomized, double-blind, placebo-controlled, phase 3 trial

Entinostat plus exemestane in hormone receptor-positive (HR+) advanced breast cancer (ABC) previously showed encouraging outcomes. This multicenter phase 3 trial evaluated the efficacy and safety of entinostat plus exemestane in Chinese patients with HR + ABC that relapsed/progressed after ≥1 endocrine therapy. Patients were randomized (2:1) to oral exemestane 25 mg/day plus entinostat (n = 235) or placebo (n = 119) 5 mg/week in 28-day cycles. The primary endpoint was the independent radiographic committee (IRC)-assessed progression-free survival (PFS). The median age was 52 (range, 28-75) years and 222 (62.7%) patients were postmenopausal. CDK4/6 inhibitors and fulvestrant were previously used in 23 (6.5%) and 92 (26.0%) patients, respectively. The baseline characteristics were comparable between the entinostat and placebo groups. The median PFS was 6.32 (95% CI, 5.30-9.11) and 3.72 (95% CI, 1.91-5.49) months in the entinostat and placebo groups (HR, 0.76; 95% CI, 0.58-0.98; P = 0.046), respectively. Grade ≥3 adverse events (AEs) occurred in 154 (65.5%) patients in the entinostat group versus 23 (19.3%) in the placebo group, and the most common grade ≥3 treatment-related AEs were neutropenia [103 (43.8%)], thrombocytopenia [20 (8.5%)], and leucopenia [15 (6.4%)]. Entinostat plus exemestane significantly improved PFS compared with exemestane, with generally manageable toxicities in HR + ABC (ClinicalTrials.gov #NCT03538171).

Meta-analysis of efficacy and safety of CDK4/6 inhibitor combined with endocrine in the treatment of HR+/HER2－ breast cancer / 中国药房

OBJECTIVE To evaluate the efficacy and safety of four cyclin-dependent kinase 4/6 （CDK4/6） inhibitors （dalpicilib， abemacilib， ribocilib， palbocilib） combined with endocrine drugs in the treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative （HR+/HER2－） breast cancer. METHODS Computer searches were conducted on PubMed， the Cochrane Library， Web of Science， Embase， CNKI， Wanfang data and VIP to collect randomized controlled trials （RCTs） about CDK4/6 inhibitors combined with endocrine drugs （trial group） versus endocrine drugs alone or combined with placebo （control group）. The search period was from the establishment of the database to April 2023. After literature screening， data extraction and quality evaluation， a meta-analysis was conducted by using RevMan 5.4.1 software. RESULTS A total of 22 articles were included， involving 15 RCTs with a total of 18 574 patients. The meta-analysis results showed that the progression free survival [HR＝0.77， 95%CI （0.74， 0.79）， P＜0.000 1]， overall survival [HR＝0.91， 95%CI （0.87， 0.94）， P＜0.000 01]， objective response rate [OR＝1.71， 95%CI （1.51， 1.93）， P＜0.000 01] and clinical benefit rate [OR＝1.73， 95%CI （1.52， 1.95）， P＜0.000 01] of the trial group were significantly better than control group. The incidence of adverse drug reactions≥3 levels [OR＝10.28，95%CI （6.97，15.17），P＜0.000 01]， neutropenia [OR＝65.09， 95%CI （36.43， 116.31）， P＜0.000 01]， leukopenia [OR＝22.90， 95%CI （15.40， 34.04）， P＜0.000 01]， anemia [OR＝5.71， 95%CI （4.51， 7.22）， P＜0.000 01]， diarrhea [OR＝ 3.00， 95%CI （1.19， 7.51）， P＜0.05] and nausea [OR＝1.99， 95%CI （1.52， 2.60）， P＜0.000 01] in the trial group was significantly higher than control group. CONCLUSIONS The combination of CDK4/6 inhibitors and endocrine drugs has a significant effect on HR+/HER2－ breast cancer， with a high incidence of adverse reactions， especially hematotoxicity.

Expert consensus on the management of adverse events of CDK4/6 inhibitors in breast cancer / 中华肿瘤杂志

Cyclin-dependent kinases 4/6 (CDK4/6) inhibitors are anti-tumor agents for the treatment of hormone receptor-positive breast cancer. Palbociclib, abemaciclib and dalpiciclib have been approved for the treatment of breast cancer in China. Common adverse effects of CDK4/6 inhibitors include bone marrow suppression, gastrointestinal toxicities, liver dysfunction, and skin or subcutaneous tissue adverse reactions (AEs). The Breast Cancer Expert Group of Chinese Society of Clinical Oncology (CSCO) summarized the incidence, clinical manifestations, and grading of the AEs. This expert consensus reports measures of AE management on the basis of experience of clinical practice and the latest advances worldwide, aiming to guide clinical practice by the way of managing AE and help to choose the best treatment regimen.

Clinical observation of metformin in treatment of endocrine resistance and postmenopausal hormone receptor positive advanced breast cancer / 实用医学杂志

Objective To evaluate the efficacy and security of metformin in the treatment of endocrine resistance and postmenopausal hormone receptor positive advanced breast cancer. Methods 60 cases of postmenopausal HR+advanced breast cancer whose first-line or second-line endocrine therapy failed were randomly divided into study group(n=30),treated with metformin combined with AI and control group(n=30),treated with placebo combined with AI. Standard RECIST guidelines were used to evaluate the clinical response. The objective response rate(ORR),clinical benefit rate(CBR),progression-free survival,and adverse reactions of two groups were compared. Results The ORR of two groups were 16.7%and 10%respectively and the difference was not statistically significant(P > 0.05). But CBR in study group was significantly higher than that in control group (63.3%vs 36.7%),and the difference was statistically significant(P<0.05). The median PFS in study group was slightly longer than that in control group (3.7 m vs 4.2 m),but there was no statistical difference. Multivariate regression analysis showed that PFS was only associated with the previous endocrine therapy. No serious adverse reactions occurred in two groups. Conclusion Metformin is expected to improve secondary endocrine resistance in breast cancer,but large prospective clinical studies are needed to confirm it.

Advances of target therapy in hormone-receptor-positive breast cancer / 中国肿瘤临床

Hormone therapy is a major treatment option for hormone-receptor-positive (HR+) breast cancer. Resistance to hormone therapy is the major reason for disease recurrence and progression. Recent studies have identified several resistance mechanisms that lead to the estrogen-independent growth of HR+breast cancer and were exploited to develop novel target drugs, including cyclin-de-pendent kinases 4 and 6 (CDK4/6) inhibitor, mammalian target of rapamycin (mTOR) inhibitor, epidermal growth factor receptor family inhibitor, vascular endothelial growth factor inhibitor, histone deacetylase inhibitor, fibroblast growth factor receptor inhibitor, insulin-like growth factor receptor inhibitor, and checkpoint inhibitor. These inhibitors are being developed to block resistance pathways and improve the efficacy of hormonal therapy. Among these drugs, the mTOR inhibitor everolimus and the CDK4/6 inhibitor palbociclib are currently approved in the United States to treat metastatic HR+breast cancer. In this study, we summarize the frontier advances in the combination of hormone and target therapies.

Efficacy of Letrozole as First-Line Treatment of Postmenopausal Women with Hormone Receptor–Positive Metastatic Breast Cancer in Korea / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Letrozole showed efficacy and generally favorable toxicities, along with the convenience of oral administration in postmenopausal patients with hormone receptor (HR)–positive metastatic breast cancer (MBC). To the best of our knowledge, there have been no reports of the clinical outcomes in Korean patients, although letrozole is widely used in practice. Therefore, this studywas conducted to affirm the efficacy and toxicities of letrozole in Korean patients. MATERIALS AND METHODS: This study retrospectively analyzed 84 HR-positive MBC patients who had been treated with letrozole from January 2001 to December 2012. Clinicopathological characteristics and treatment history were extracted from medicalrecords. All patients received 2.5 mg letrozole once a day until there were disease progressions or unacceptable toxicity. Progression-free survival (PFS) was the primary endpoint, and secondary endpoints were overall survival (OS), objective response rate (ORR), and toxicity. RESULTS: The median age of the subjects was 59.3 years. Letrozole treatment resulted in a median PFS of 16.8 months (95% confidence interval [CI], 9.8 to 23.8) and a median OS of 56.4 months (95% CI, 38.1 to 74.7). The ORR was 36.9% for the 84 patients with measurable lesions. Multivariate analysis revealed symptomatic visceral disease (hazard ratio, 3.437; 95% CI, 1.576 to 7.495; p=0.002) and a disease-free interval ≤ 2 years (hazard ratio, 2.697; 95% CI, 1.262 to 5.762; p=0.010) were independently associated with shorter PFS. However, sensitivity to adjuvant hormone treatment was not related to PFS. Letrozole was generally well tolerated. CONCLUSION: Letrozole showed considerable efficacy and tolerability as a first-line treatment in postmenopausal patients with HR-positive MBC.

Advances of fulvestrant in treatment of advanced breast cancer in hormone receptor-positive postmenopausal women / 中国癌症杂志

Endocrine therapy targeting estrogen pathway is one of the ifrst-line treatment choices of advanced breast cancer. Fulvestrant is a pure estrogen antagonist that blocks and downgrades estrogen receptor, which makes it effective in the treatment of progression after prior endocrine therapy. Fulvestrant 250 mg per month regime was approved for postmenopausal women with hormone-positive advanced breast cancer after progression or recurrence on antiestrogen therapy. Fulvestrant 500 mg per month regime was approved by the EMA and the US FDA in the same population based on the CONFIRM trial which proved improved efifcacy and similar tolerance compared with 250 mg regime. Recent trials were focused in the ifrst-line treatment and combination use with other therapeutics. This review discusses the advances of fulvestrant in postmenopausal women with hormone-positive advanced breast cancer.