Table 3.
Biomarkers in HR+ breast cancer.
| Biomarker | Prognostic | Predictive | Pharmacodynamic | Reference |
|---|---|---|---|---|
| Histopathology | ||||
| Tumour grade | Y | N | N | [38] |
| Pathological prognostic stage | Y | N | N | [39] |
| ER | Y | Y. to ET-based therapy | N | [9,40,41,42] |
| PR | Y | N | N | [43,44] |
| AR | N | N | N | [45] |
| HER2 | Y | Y. to HER2-targeted therapy | N | [46] |
| Ki67 | Y | N | N | [47] |
| Ki67 response to 2 weeks of preoperative ET | Y | N | Y | [48,49] |
| PDL1 and TILs | Y. to TILs only | Y. to immunotherapy | N | [50,51,52,53] |
| Genomic | ||||
| Multigene tests | Y | Y. to chemotherapy * | N | [54,55] |
| ER activation gene signature | N | Y. to SERDs | N | [56] |
| ESR1mut | Y | Y. to SERDs | Y | [12,57] |
| PIK3CA mut | Y | Y. to alpelisib | N | [20] |
| AKTmut | N | Y. to capivarsertib | N | [58] |
| ERBB2mut | N | Y. to HER2-targeted therapy | N | [59,60] |
| BRCA1/2mut | Y | Y. to PARPi | N | [30,61] |
| Cell cycle molecules | N | Y. to CDK4/6i | N | [62,63,64] |
| Imaging | ||||
| FDG-PET | Y | N | Y | [65] |
| FES-PET | Y | Y. to SERDS | Y | [65,66] |
ET: endocrine therapy; ER: estrogen receptor; PR: progesterone receptor; AR: androgen receptor; PDL1: programmed death ligand 1; TIL: tumour-infiltrating lymphocytes; SERD: selective estrogen receptor downregulator; ESR1: estrogen receptor 1; PIK3CA: phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α; BRCA1/2: breast cancer gene 1/2; CDK4/6: cyclin-dependent kinase 4/6; PARPi: poly(ADP-ribose) polymerase inhibitor; FDG-PET: fluorodeoxyglucose positron emission tomography; FES-PET: 16α-[18F]fluoro-17β-estradiol positron emission tomography. Y represents clinically validated biomarkers to date. * Oncotype and Mammaprint only.