Extended Data Fig. 2: ESR1 mutation analysis.

Droplet digital PCR detection of Y537S homozygous ESR1 mutation in HCI-044 PDX tumors (a) and Y537S low allele frequency tumors in HCI-018 PDX (b) and HCI-032 PDX (c). 2D scatter plots of ddPCR results showing fluorescent detection of individual droplets with either gDNA or cDNA. Blue and green dots represent droplets with WT or mutant ESR1 genotypes indicated on the right panel of each plot, respectively. Orange dots represent droplets containing both WT and mutant ESR1 DNA. Black dots represent droplets without DNA. Mutation allele frequencies are labelled accordingly.