Metabolic alterations driven by PFKFB3 upregulation confer resistance to trastuzumab in HER2-positive breast cancer.

AIMS: Resistance to anti-HER2 therapies, particularly trastuzumab, remains a major obstacle in the treatment of HER2-positive (HER2 +) breast cancer. This study aims to uncover novel mechanisms driving trastuzumab resistance with a focus on the immune component, key mediator of trastuzumab efficacy.

METHODS: We developed an isogenic cell line-derived xenograft model to perform transcriptome-wide analyses of trastuzumab-sensitive and -resistant tumors. To validate key findings, we employed a 3D cancer-immune co-culture system capable of quantifying antibody-dependent cellular cytotoxicity (ADCC).

RESULTS: Transcriptomic profiling revealed how trastuzumab treatment shifts tumor transcriptomes, including changes that remodel the metabolic landscape and distinct gene signatures associated with resistance, notably the upregulation of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). Functional studies demonstrated that PFKFB3 promotes trastuzumab resistance by inducing metabolic rewiring and reducing ADCC. Silencing PFKFB3 restored immune-mediated cytotoxicity. Clinical dataset analyses confirmed that elevated PFKFB3 expression correlates with reduced overall and progression-free survival, and with incomplete pathological response to trastuzumab.

CONCLUSIONS: PFKFB3 upregulation drives metabolic adaptations that confer resistance to trastuzumab in HER2 + breast cancer. These findings highlight PFKFB3 as a promising therapeutic target to overcome resistance and improve patient outcomes.