Table 1.

Examples and uses of mechanistic biomarkers for immune-related diseases and cancer

Type of Biomarker	Biomarker	Use of Biomarker	Development Stage
Cytokine	IL-7	Prediction of responsiveness to IFN-β in MS	Retrospective testing in samples from clinical trials45
Chemokine	CXCL13	Assessment of disease activity in RA Prediction of disease progression in RA Assessment of response to TNF blockade Prediction of the rate of B-cell repopulation after rituximab therapy	All uses are undergoing retrospective testing in samples from clinical trials55,56,57,58
Cell type	TH1 cells, TH17 cells	Prediction of responsiveness to IFN-β in MS	Retrospective testing in samples from clinical trials44
Autoantibodies	ACPA	Diagnosis of symptomatic RA Diagnosis of asymptomatic RA	Clinical practice Retrospective testing in samples from clinical studies10
	ANA	Diagnosis of symptomatic SLE	Clinical practice
Signalling molecule	ErbB2	Prediction of responsiveness to anti-ErbB2 monoclonal antibodies and to tyrosine kinase inhibitors in breast cancer	Clinical practice
Gene expression	Wound-healing signature	Identification of women with breast cancer who do not need adjuvant chemotherapy	Retrospective testing in samples from clinical studies42
	IFN-α/β-inducible gene signature	Assessment of the efficacy of anti-IFNα monoclonal antibody therapy in neutralizing IFN-α and downstream signalling in SLE	Prospective testing in clinical trials26
	Imatinib-responsive gene signature	Identification of systemic sclerosis patients most likely to respond to treatment with the tyrosine kinase inhibitor imatinib	Retrospective testing in samples from clinical trials43

Abbreviations: ACPA, anti-citrullinated protein antibodies; ANA, anti-nuclear antibodies; CXCL13, C-X-C motif chemokine 13; ErbB2, Receptor tyrosine-protein kinase erbB-2; MS, multiple sclerosis; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; T_H1, type 1 T helper (cell); T_H17, type 17 T helper (cell).