However, O'Byrne et al. showed that 6 months treatment with AZD5069 did not reduce the frequency of severe exacerbations in patients with uncontrolled severe asthma, thereby questioning the role of CXCR2-mediated neutrophil recruitment in the pathobiology of exacerbations in severe refractory asthma [41]. This evidence concerns the gene CXCR2 and asthma.