Reduction in measures of mast cell burden: pooled results from the phase 1 EXPLORER and interim phase 2 PATHFINDER studies. Waterfall plots demonstrating maximum percentage change from baseline in BM mast cell burden, serum tryptase level, spleen volume, and KIT D816V VAF. Data cutoff dates were 27 May 2020 for EXPLORER and 23 June 2020 for PATHFINDER. ^aCalculation includes patients without postbaseline assessments who were excluded from the waterfall plot.