TABLE 2.

Categorization of CDTs Based on Regulatory Status and Clinical Effect

		CDT Regulatory Status
		Required Tests Required in FDA Drug Label	Optional (Not Required) Tests Not Required in FDA Drug Label
Treatment Prediction	Efficacy CDTs that predict treatment response	Examples ➢ Vemurafenib and BRAF V600E for metastatic melanoma ➢ Crizotinib and ALK for NSCLC	Examples ➢ Warfarin and VKORC1 ➢ Clopidogrel and CYP2C19 ➢ OncotypeDx: breast
	Safety CDTs that predict the risk of adverse events	Examples ➢ Abacavir and HLA-B*5701	Examples ➢ Carbamazepine and HLA-B*1502 ➢ Warfarin and CYP2C9 ➢ Azathioprine and TPMT ➢ Irinotecan and UGT1A1

ALK = anaplastic lymphoma kinase; CDT = companion diagnostic test; FDA = U.S. Food and Drug Administration; HLA = human leukocyte antigen; NSCLC = non-small cell lung cancer; TPMT = thiopurine s-methyltransferase.