KIT and systemic mastocytosis: 2015). However, imatinib has demonstrated only modest activity against the KIT D816V mutation in vitro and in the clinic (Lim et al. 2009a; Vega-Ruiz et al. 2009; Gleixner et al. 2006). For example, a study including 22 patients with SM treated with imatinib demonstrated an ORR of 33.3 % in patients without the KIT D816V mutation, 16.7 % in patients with this mutation, and 0 % in patients with missing mutation data (Lim et al. 2009a).