The National Institutes of Health Biomarkers Definitions Working Group defines a biomarker as “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.” Biomarkers may be used to predict response and modify therapy, such as escalate, de-escalate, or change therapy. At the 5th annual CCA Summit meeting, Kristen Spencer, DO, MPH, discussed the utility of biomarkers to predict treatment response in biliary tract cancers (BTC).1
Several molecular features have been identified in BTCs that may predict treatment responses or modify therapy. Yoon and colleagues reported that BTCs harboring mutations and chromosomal instability were associated with resistance to PD-1/PD-L1 blockade and low tumor-infiltrating lymphocyte density, indicating immune-suppressive tumor microenvironments.2 In contrast, among 65 patients with IDH-mutated pathologically confirmed BTC who had received first-line palliative chemotherapy, overall response rate was significantly longer in patients who received gemcitabine-containing regimens than in those who received non–gemcitabine-containing regimens (39% vs 0%; P =.02).3 Serum carbohydrate antigen 19-9 (s-CA19-9) concentration was identified as a preoperative predictor of lymph node (LN) metastasis, with significantly higher concentrations in N1 versus N0 subgroups. Moreover, high s-CA19-9 (≥100 U/mL, 12 months vs <100 U/mL, 59 months) and LN status (N1, 16 months vs N0, 55 months) predicted worse survival post-hepatectomy.4 Strong evidence indicates that multiple point mutations in FGFR confer resistance to FGFR2 inhibitors, which may inform potential treatment changes.5,6
These data support the concept that emerging biomarkers based on molecular features of BTCs may be useful to predict treatment response and further guide the management of advanced BTCs.
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