Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have led transformative breakthrough of clinical therapy for hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER-2)-negative breast cancer patients. CDK4/6 inhibitors that have been marketed in China include Ribociclib, Palbociclib, Abemaciclib and Dalpiciclib. For HR-positive HER-2-negative locally advanced and metastatic breast cancer, CDK4/6 inhibitors combined with endocrine therapy have become standard regimen, which can prolong the survival of patients. In the adjuvant treatment stage of early breast cancer, CDK4/6 inhibitors have also achieved positive results and been approved for indications. At present, CDK4/6 inhibitors have been widely used in clinical practice in China. In order to further improve the standardized application of CDK4/6 inhibitors in China, the Breast Cancer Expert Committee of the National Center for Cancer Quality Control and the Professional Committee of Clinical Research of Cancer Drugs of the Chinese Anti-Cancer Association organized the related expert to update the consensus based on the \"CDK4/6 inhibitor consensus on clinical application of in the treatment of hormone receptor positive human epidermal growth factor receptor 2 negative advanced breast cancer (2021 edition)\" . The updated consensus systematically introduces the pharmacological characteristics, drug monitoring and adverse event management, etc., of CDK4/6 inhibitors to promote the accuracy of clinical decision-making with the ultimate goal to prolong the overall survival of patients and improve the quality of life.
细胞周期蛋白依赖性激酶4/6 (CDK4/6)抑制剂为激素受体(HR)阳性、人表皮生长因子受体2(HER-2)阴性乳腺癌患者的临床治疗模式带来变革性的突破。中国已上市的CDK4/6抑制剂包括瑞波西利、哌柏西利、阿贝西利和达尔西利。对于HR阳性HER-2阴性局部晚期和转移性乳腺癌，CDK4/6抑制剂联合内分泌治疗已经成为标准方案，能够延长患者的生存。在早期乳腺癌辅助治疗阶段，也已有CDK4/6抑制剂取得阳性结果并获批适应证。目前，CDK4/6抑制剂广泛进入中国临床实践，为进一步提高CDK4/6抑制剂在中国的规范化应用，国家肿瘤质控中心乳腺癌专家委员会和中国抗癌协会肿瘤药物临床研究专业委员会在2021版《CDK4/6抑制剂治疗激素受体阳性人表皮生长因子受体2阴性晚期乳腺癌的临床应用共识》基础上，组织相关领域专家，对该共识进行更新，系统性介绍CDK4/6抑制剂的药理学特征、在晚期及早期乳腺癌中的适应证、患者用药监测以及不良事件管理等，以期推进临床决策的精准性，达到延长患者生存时间和提高生活质量的最终目标。.

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.
细胞周期蛋白依赖性激酶4/6(CDK4/6)抑制剂是治疗激素受体阳性乳腺癌的抗肿瘤药物，其中，哌柏西利、阿贝西利和达尔西利已在中国获得批准用于乳腺癌的治疗。CDK4/6抑制剂常见的不良反应包括骨髓抑制、胃肠道不良反应、肝功能异常、皮肤及皮下组织不良反应等。中国临床肿瘤学会乳腺癌专家委员会共识专家组总结了CDK4/6抑制剂常见不良反应的发生率、临床表现和严重程度分级，结合临床经验并参考国内外研究进展，制定了不良事件的管理措施，形成乳腺癌CDK4/6抑制剂相关性不良反应管理共识，旨在从不良反应管理角度更好地指导临床实践，帮助选择CDK4/6抑制剂最佳治疗方案。.

OBJECTIVE: Breast cancer in young Asian women has distinctive clinicopathological characteristics; hence, we question the universal generalizability of treatment recommendations based on data from predominantly non-Asian postmenopausal women.
METHODS: The Asian Breast Cancer Cooperative Group (ABCCG) reviewed current ESO-ESMO and St. Gallen recommendations for treating hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer in premenopausal women. Points disputed by ≥ 3/12 members were discussed, and statements on contentious issues formulated for anonymous voting; consensus required a ≥ 75% majority.
RESULTS: The ABCCG contends that: (1) Trials in premenopausal women are not only necessary, but also worthwhile if performed separately from others that also enroll postmenopausal participants. (2) Not all premenopausal women with HR+ early breast cancer need adjuvant ovarian function suppression (OFS). (3) Certain clinical factors might influence decision-making about prescribing OFS. (4) For early HR+/HER2- breast cancer in premenopausal patients with OFS, tamoxifen is preferred for intermediate-risk cases; for high risk, near-consensus supported aromatase inhibitor, despite no clear overall survival benefit versus tamoxifen. (5) Oncotype DX Breast Recurrence Score® has different treatment implications in patients aged ≤ 50 versus > 50 years. (6) High-risk patients (if premenopausal after chemotherapy) should receive adjuvant chemotherapy and OFS plus aromatase inhibitor. (7) For patients with advanced disease receiving OFS on a backbone of tamoxifen, gonadotrophin-releasing hormone agonists may be given 12-weekly. (8) For premenopausal women who decline OFS or oophorectomy, tamoxifen alone is still an option but is considered less effective; other monotherapies are also less effective than OFS plus such treatments.
CONCLUSIONS: Premenopausal Asian women with breast cancer have unique disease characteristics and may benefit from treatment that differs somewhat from international guidelines. Given the great diversity of patients and clinical settings worldwide, the ABCCG advocates evidence-based yet flexible and individualized use of all potential options to improve breast cancer outcomes.