. 2017 Oct 9;29(1):24–34. doi: 10.1681/ASN.2017010004

Table 1.

Overview of biomarker subtypes and examples for the assessment of kidney allografts

Biomarker Type	Biomarker Definition	Established Examples in Transplantation	Potential New Examples in Transplantation That Are Insufficiently Validated for Clinical Use
Susceptibility/risk biomarker	A biomarker that indicates the potential for developing a disease, medical condition, or sensitivity to an exposure in an individual without clinically apparent disease or medical condition	Number of HLA mismatches	Epitope mismatch load¹⁸
		Pretransplant PRA percentage	Urinary or serum suPAR for FSGS recurrence⁵⁴
		Pretransplant DSA	FSGS recurrence panel²¹
		De novo DSA occurrence	Phospholipase A2 receptor and thrombospondin type 1 domain–containing 7A antibodies for recurrence of membranous glomerulopathy^22,23
		Genetic assessment for atypical hemolytic uremic syndrome recurrence	Donor-reactive T cell response⁵⁵
Diagnostic biomarker	A biomarker used to identify individuals with the disease or condition of interest or define a subset of the disease	Serum creatinine/GFR	Urinary three-gene mRNA expression signature and wide range of other suggested molecules^11,31
		Proteinuria	Wide range of urinary target proteins, like CXCL10 and CXCL9¹¹
		Hematuria	Blood 17-gene mRNA expression “kSORT”³³
		DSA	Blood 200-gene mRNA expression “TruGraf”³²
		Signs of hemolysis	Several blood and urine miRNAs¹¹
		Renal ultrasound examination	Molecular microscope for allograft pathology^a
		Protocol or for-cause biopsy histology^a
Prognostic biomarker	A biomarker used to identify likelihood of a clinical event, disease recurrence, or progression	Serum creatinine/GFR	Complement-fixing characteristics of DSA^39,40
		Proteinuria	Edmonton^a classifier for graft loss⁴²
		DSA	Edmonton^a “ABMR molecular score”⁴⁵
		Protocol or for-cause biopsy histology (rejection subtype, chronic injury, PVAN stage, etc.)^a	GOCAR^a 13-gene set⁴³
Predictive biomarker	A biomarker used to identify individuals who are more likely than similar patients without the biomarker to experience a favorable or unfavorable effect from a specific intervention or exposure	There are currently no established predictive biomarkers proposed for treatment of transplant pathologies	There are currently no new predictive biomarkers proposed in kidney transplantation
Predictive biomarker			Suggestions made in the past are complement-fixing characteristics of DSA for use of complement inhibitors (no studies) and intrarenal C4d deposition for use of complement inhibitors (no studies)
Monitoring biomarker	A biomarker measured serially and used to detect a change in the degree or extent of disease; monitoring biomarkers may also be used to indicate toxicity, assess safety, or provide evidence of exposure, including exposures to medical products	Serum creatinine/GFR	There are currently no new monitoring biomarkers proposed in kidney transplantation
		Proteinuria
		Hematuria
		Immunosuppressive drug levels
		BKV PCR
		Signs of hemolysis
Pharmacodynamic/response biomarker	A biomarker used to show that a biologic response has occurred in an individual who has received an intervention or exposure	CD19/CD20 count with rituximab treatment	There are currently no new pharmacodynamic/response biomarkers proposed in kidney transplantation
		DSA mean fluorescence index after ABMR treatment
		Post-treatment control biopsy histology (resolution of disease and disease activity)^a
Safety biomarker	A biomarker used to indicate the presence or extent of toxicity related to an intervention or exposure	Immunosuppressive drug levels	There are currently no new safety biomarkers proposed in kidney transplantation
		Peripheral blood cell counts
		Liver tests
		Diabetes occurrence
		Calcineurin inhibitor nephrotoxicity (biopsy histology)^a

Definitions are derived from the Food and Drug Administration/National Institutes of Health Biomarker Working Group.⁵⁶ This is not an exhaustive list.

Invasive biomarkers.