Table 2.

Overview of HER2-Low.

Study	Study design	N	IHC 1+	IHC 2+	ISH	HER2-Low	Assay
LA/mUC
Fleischmann 2011	Observational	150	11.4%	4.7%	n=147FISH+: 8.8%Borderline +: 4.8%FISH-: 86.4%	13.4%	Dako HercepTest (IHC)Abbott/Vysis PathVysion HER2 DNA Probe Kit (FISH)
Banerji 2019	Clinical trial, phase I	16	12.5%	56.3%	Performed only for 2+ (n=16)ISH+: 11.1%/ISH-: 43.8%ISH unevaluable: 6.3%	56.3%	N/A
Weighted average of HER2-Low defined as IHC 2+ and ISH/FISH- or IHC 1+: 17.5%
Earlier stage UC
Latif 2003	Observational	25	4.0%	16.0%	FISH+: 8.0%	20.0%	Ventana monoclonal anti-human HER-2 protein CB11 (IHC), Vysis (FISH)
Weighted average of HER2-Low defined as IHC 2+ and ISH/FISH- or IHC 1+: 20.0%

FISH, fluorescence in situ hybridization; FISH+, FISH positive; FISH-, FISH negative; HER2, human epidermal growth factor receptor; IHC, immunohistochemistry; ISH, in situ hybridization; ISH+, ISH positive; ISH-, ISH negative; N/A, not available.