Table 1.

Actionability of alterations as per ESCAT

	Readiness of use in clinical practice	ESCAT for alterations in breast cancer	Prevalence in the AURORA population	Cumulative prevalence in the AURORA population
Tier I	Targets ready for implementation in routine clinical decisions	ERBB2 amplification (IA), germline BRCA1/2 mutations (IA), PIK3CA mutations (IA), MSI (IC), TRK fusions (IC)	143 (38%)	143 (38%)
Tier II	Investigational targets likely to define patients who benefit from a targeted drug, but additional data needed	PTEN loss (IIA), ESR1 mutations (IIA), AKT1 mutations (IIB), ERBB2 mutations (IIB)	65 (17%)	193 (51%)
Tier III	Clinical benefit previously demonstrated in other tumor type or for similar molecular targets	Somatic BRCA1/2 mutations (IIIA), MDM2 amplification (IIIA), ERBB3 mutations (IIIB)	35 (13%)	206 (54%)
Tier IV	Preclinical evidence of actionability	ARID1A/B, ATM/ATR/PALB2, CDH1, IGF1R, INPP4B loss, MAP2K4/MAP3K1, MT4, MYC, NF1, PIK3R1, RUNX1/CBFB, SF3B1, TP53 (IVA)	233 (61%)	313 (83%)
Tier V	Evidence supporting co-targeting approaches
Tier X	Lack of evidence of actionability	FGFR1 amplification, CCND1 amplification	99 (26%)	328 (86%)

NOTE: We have reproduced the different molecular alterations and their level of evidence as per ESCAT (18). The molecular alterations reported on a sample-per-samples basis in AURORA are in bold.