Pharmacometabonomics Analysis Reveals Serum Formate and Acetate Potentially Associated with Varying Response to Gemcitabine-Carboplatin Chemotherapy in Metastatic Breast Cancer Patients

Gemcitabine-carboplatin (GC) chemotherapy was efficacious in metastatic breast cancer (MBC) patients probably resistant to anthracyclines and taxanes, but showed significant interindividual variation in treatment responses. Early prediction of response to treatment is clinically relevant to identify patients who will achieve clinical benefit. In this study, nuclear magnetic resonance (NMR) based pharmacometabonomics was used to noninvasively predict the response to GC chemotherapy of 29 MBC patients with prior exposure to both anthracyclines and taxanes from a phase II study. Formate and acetate levels in the baseline serum collected prior to GC chemotherapy were identified as potential predictive markers to select patients who will achieve clinical benefit and to identify those who should not be treated with the therapy to avoid futile treatment. The significantly lower baseline levels of serum formate and acetate in patients with resistant disease may reflect the higher demand of them as alternate/additional nutritional sources to fuel the accelerated proliferation of breast cancer cells that are biologically more aggressive or resistant to therapy. The results suggest that pharmacometabonomics can be a potential useful tool for predicting chemotherapy response in the context of precision medicine. Prospective studies with larger patient cohorts are required for validation of the findings.