Fragement C Gamma receptor IIIa polymorphism is predictive of trastuzumab efficacy in the neoadjuvant setting of HER2-positive breast cancer patients.

Abstract

e12607 Background: Antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the most important mechanisms of Trastuzumab. Fragement C Gamma receptor (FcγR) IIA and IIIA polymorphisms influence the affinity of immunoglobin G (IgG). Recently, FcγRIIA and FcγRIIIA polymorphisms have identified with the efficacy of trastuzumab. However, whether FcγR polymorphisms are associated with the efficacy of trastuzumab in the neoadjuvant setting was unclear. Methods: We retrospectively enrolled 101 patients with HER2-positive breast cancer receiving chemotherapy plus trastuzumab as neoadjuvant therapy and mastectomy in Sun Yat-sen university cancer center from May 2015 to March 2021. Among them, twenty patients were excluded because lacking of blood samples. Clinical and pathological characteristics, treatments and outcomes of patients were collected. We purified the genomic DNA from peripheral blood samples, performed nested polymerase chain reaction (PCR) and sanger sequencing to identify the polymorphisms of FcγRIIA(rs1801274) and FcγRIIIA(rs396991). Results: Patient samples (n=81) were successfully detected. No significant differences between FcγRIIA/FcγRIIIA genotypes and clinical characteristics, including age, clinical stage, menstrual status, molecular subtyping, treatment and pathological complete response (pCR) rate. In subgroup analyses, FcγRIIIA polymorphism was significantly correlated with pCR rate in the population who received paclitaxel plus trastuzumab therapy (n=34, P<0.05). The Kaplan-Meier analyses showed that no significant difference in disease-free survivals (DFS) between FcγRIIA-131 H/H and R carriers genotype groups ( P=0.24), either that in the FcγRIIIA-158 F/F and V carriers genotype groups ( P=0.60). But the DFS in FcγRIIIA-158 V carriers genotype group were significant longer than that in FcγRIIIA-158 F/F genotype group in subgroup who received paclitaxel plus trastuzumab therapy (n=34, P=0.036), while that was not significant difference in patients with anthracycline-based treatment (n=47, P=0.248). DFS has not yet been reached. Conclusions: FcγRIIIA polymorphism is predictive of trastuzumab efficacy in the neoadjuvant setting of HER2-positive breast cancer patients who received paclitaxel plus trastuzumab therapy. Anthracycline-based treatment may improve the outcomes of HER2 positive breast cancer patients with FcγRIIIA-158 F/F genotype.[Table: see text]