Genetic susceptibility genes and clinical features of early-onset breast cancer / 国际肿瘤学杂志

Objective:To explore the germline mutation frequency of genetic susceptibility genes and clinical characteristics in early-onset breast cancer (onset age ≤35 years) in China.Methods:Clinical information and peripheral blood of 150 patients aged 35 and younger diagnosed with breast cancer in Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College from January 1, 2015 to December 31, 2019 were collected. Then DNA was extracted to detect germline mutations in breast cancer susceptibility gene (BRCA) 1, BRCA2, ataxia telangiectasia mutated (ATM) , partner and localizer of BRCA2 (PALB2) , tumor protein 53 (TP53) and cell cycle checkpoint kinase 2 (CHEK2) genes. Mutations were interpreted as pathogenic, likely pathogenic, uncertain significance, likely benign and benign according to the classification criteria and guidelines for genetic variation. Patients were divided into mutation group ( n=18) and non-mutation group ( n=132) according to the presence or absence of pathogenic or probable pathogenic germline mutations, and the χ2 test was used to analyze the relationships between genetic susceptibility gene mutations and clinicopathological characteristics. Results:Eighteen pathogenic or likely pathogenic germline mutations were detected in 150 patients with early-onset breast cancer, for an overall mutation frequency of 12.0%. Among them, there were 8 (5.3%) BRCA2 mutation, 7 (4.7%) BRCA1 mutation, 1 (0.7%) PALB2 mutation, and 2 (1.3%) TP53 mutation. There were no pathogenic or likely pathogenic variants in ATM and CHEK2 genes. The mutation type was dominated by frameshift mutation (9/18, 50.0%) , followed by nonsense mutation (7/18, 38.9%) , missense mutation (1/18, 5.6%) and splice acceptor mutation (1/18, 5.6%) . Among the molecular subtypes of 18 mutation carriers, 9 cases were Luminal B, 6 cases were triple negative breast cancer (TNBC) , 2 cases were Luminal A, and only 1 case was human epidermal growth factor receptor-2 (HER-2) amplification. Among them, 8 BRCA2 mutation carriers were Luminal type, and 6 of 7 BRCA1 mutation carriers were TNBC type. There were no statistical differences in family history of breast cancer ( P=0.343) , estrogen receptor (ER) status ( χ2=0.16, P=0.688) , HER-2 status ( χ2=2.89, P=0.089) , molecular subtype ( χ2=1.99, P=0.575) , and initial diagnosis TNM stage ( χ2=2.49, P=0.115) between the mutation group and the non-mutation group. Conclusion:The patients with early-onset breast cancer have high frequency of germline mutations. It is recommended that patients with early-onset breast cancer undergo genetic counseling and multigene testing.

Antibody-drug conjugates in HER2-positive breast cancer / 中华医学杂志(英文版)

Antibody-drug conjugates (ADCs) combine the high specificity of monoclonal antibodies with the high anti-tumor activity of small molecular cytotoxic payloads. The anti-tumor activity of ADCs is mainly achieved by the direct blocking of the receptor by monoclonal antibodies, direct action and bystander effect of cytotoxic drugs, and antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. ADCs have been used in adjuvant therapy and rescue treatment of human epidermal receptor 2 (HER2)-positive breast cancer, greatly improving the prognosis of breast cancer patients. Several ongoing clinical trials of ADC for breast cancer and other solid tumors proved the potential of ADCs will provide more promising treatment options for patients with malignant tumors. This review introduces the mechanism and latest clinical progress of ADC drugs approved for HER2-positive breast cancer to guide clinical practice and conduct research.

Research on the function and targeted therapy of BCL9 in malignant tumors / 国际肿瘤学杂志

Canonical Wnt/β-catenin signaling pathway is of great significance to the occurrence and progression of tumors which make it an exciting target in cancer therapy. The pathway is also required in regeneration of normal tissues, so the specificity of inhibitors targeting this pathway may be affected. The coactivator of β-catenin, B cell lymphoma 9 (BCL9), is highly expressed merely in tumor cells. Accordingly, inhibitors targeting the interaction between β-catenin and BCL9 may demonstrate robust specificity and minimal toxicity. BCL9 increases tumor growth, invasion and metastasis by promoting epithelial-mesenchymal transition, up-regulating vascular endothelial growth factor and CD44 expression and regulating cancer stem cell traits. BCL9 promises to be a new target for cancer therapy.