e12638 Background: In the last decade, the treatment approach for locally advanced breast cancer (BC) patients has partly shifted from adjuvant treatment to neoadjuvant treatment. Systemic neoadjuvant treatment can downstage the tumor for less extensive surgery and improve cosmetic outcomes. Differential subtypes of BC responded unevenly to neoadjuvant chemotherapy. Luminal B type with the relatively higher prevalence (40% in all 4 subtypes) had better therapeutic effect to neoadjuvant treatment than luminal A type, but worse than HER2-positive patients. Methods: We enrolled 87 BC patients for genotyping with multiple cancer-related genes. Among them, 17 patients were luminal A, 21 were HER2-negative luminal B, 23 were HER2-positive luminal B, 17 were HER2-positive and 9 were triple-negative. According to the RECIST, the patients were divided into 1-4 and 5 grades. Fisher test was used to analyze the difference of SNV and CNV between the two primary tumors, as well as TMB difference between post-neoadjuvant chemotherapy and past-neoadjuvant chemotherapy. Results: Base mutations in all patients showed discrepant preference between 1-4 grades and 5 grade groups, G-to-A in 1-4 grades, while A-to-G, A-to-T and G-to-T in 5 grade. In luminal B group (combine liminal B-negative and luminal B-positive groups), FLT4 gene mutation occurred more frequent in 5 grade than 1-4 grades (4/16 vs 0/28, P = 0.01). CNV analysis in NFKBIA and ZNF217 distinguished the two therapeutic efficiency groups in luminal B-positive group. The amplification of NFKBIA and ZNF217 was higher in 1-4 grades than 5 grade (8/14 vs 1/9, P = 0.036; 9/14 vs 1/9, P = 0.017). TMB difference between post and past neoadjuvant chemotherapy in luminal B-positive group was also significant in 5 grade (4.36 vs 1.99, P = 0.002). Conclusions: NFKBIA and ZNF217 amplification notably differentiated the 1-4 grades and 5 grade groups in luminal B-positive patients, suggesting the potential prognostic biomarkers of neoadjuvant chemotherapy in this locally advanced breast cancer subtype, which would be improved by further large-scale cohort study. The differences of TMB and FLT4 gene mutation were also found between the two therapeutic efficiency groups.
PCN48 Cost-Effectiveness Analysis of Pertuzumab with Trastuzumab and Chemotherapy Compared to Trastuzumab and Chemotherapy in the Neoadjuvant Treatment of HER2-Positive EARLY or Locally Advanced Breast Cancer: Update Results after National Drug Reimbursement LIST Adjustment in China
