Table 2. ATR inhibitors and their main properties.

Compound	Enzymatic activity	In vitro selectivity	In vitro efficacy	Pharmacology	In vivo activity	Development stage
Schisandrin B	IC50 = 7.25 μM	–	R+/– C+/–	N.D.	N.D.	Optimisation stage
ETP-46464	N.D.	+	R+	—	N.D.	Optimisation stage
NU6027	N.D.	N.D.	R+/– C+	– (solubility)	N.D.	Optimisation stage
VE-821	K i = 13 nM	+	R+ C+	– (toxicity)	N.D.	Discontinued at research stage
VE-822	K i < 0.2 nM	+	M– R+ C++	+	+	Clinical trials phase I
3	IC50 = 0.4 nM	++	N.D.	+/– (toxicity)	N.D.	Research stage
AZ20	IC50 = 5 nM	+/–	M++	+/– (toxicity, solubility)	++	Clinical trials phase I
AZD6738	IC50 = 1 nM	++	M+ C++	+	+	Preclinical stage