IL15 and cancer: 2013), a recent study in cancer patients demonstrated influx and hyperproliferation of NK cells in the peripheral blood after IL‐15 administration (Conlon et al. 2015). These data suggest that IL‐15 blockade might only affect NK cell counts under conditions where IL‐15 levels are elevated (e.g., in patients with inflammatory diseases). In addition, the presented PK/PD modeling approach may be useful for guiding therapeutic dose selection of investigational agents that target the IL‐15 pathway such as JAK3 inhibitors (Conklyn et al. 2004; Borie et al. 2005).