...we assessed whether the combination of bevacizumab/paclitaxel yields sufficient anti-tumor activity to justify further exploration in advanced ER+/HER2- breast cancer patients with acquired ESR1 mutations in circulating tumor DNA (ctDNA)....The 6-month PFS rate was 83% for ESR1 wild-type patients versus 85% for ESR1 mutant patients (17/20)....This explorative study indicates that in advanced breast cancer patients with ESR1 mutations in plasma it is worthwhile to start bevacizumab/paclitaxel as further treatment.