Therapy-induced remodeling of IgG and plasma N-glycans in breast cancer.

BACKGROUND: Protein N-glycosylation plays a key role in cancer biology and may offer insights into tumor behavior and treatment response. This study investigated changes in N-glycosylation of immunoglobulin G (IgG) and total plasma proteins in patients with breast cancer undergoing neoadjuvant chemotherapy. METHODS: A prospective cohort of 34 women with early-stage or locally advanced breast cancer was recruited. Plasma samples were collected before and after neoadjuvant chemotherapy. IgG was isolated by immunoaffinity chromatography, and IgG and total plasma N-glycans were enzymatically released, fluorescently labeled, and analyzed using ultra-high performance liquid chromatography. Glycan traits were expressed as relative abundances and summarized into derived structural features. Longitudinal changes were assessed using linear mixed-effects models adjusted for age and body mass index. RESULTS: Chemotherapy induced significant decrease in IgG core fucosylation. This effect varied by treatment: anthracycline-based regimen led to decreased core fucosylation and digalactosylation and increased monogalactosylation. The greatest reduction in core fucosylation was observed in patients treated with docetaxel and cyclophosphamide. HER2-targeted therapy was associated with decreased bisecting N-acetylglucosamine. Plasma glycosylation remained largely stable, though oligomannose glycans increased in patients following chemotherapy. Tumor size was significantly associated with several plasma glycan traits, particularly digalactosylation and oligomannosylation. CONCLUSIONS: IgG glycosylation patterns change in a treatment-specific manner during chemotherapy, potentially reflecting immune modulation. Plasma glycan traits are more stable but may reflect tumor burden. These results support the potential of glycan profiling as a biomarker for monitoring the impact of therapy and disease progression in breast cancer.