ACT-1004-1239 is an orally available, potent, and selective first-in-class CXCR7 antagonist that showed efficacy in preclinical animal models of multiple sclerosis (Pouzol et al., 2021a) and acute lung injury (Pouzol et al., 2021b), and had a favorable clinical profile following single- (Huynh et al., 2021b) and multiple-dose (Huynh et al., 2021a) administration. This evidence concerns the gene ACKR3 and multiple sclerosis.