PIK3CA and breast cancer: Razavi et al published in Nature Cancer an inspiring article that performed a longitudinal analysis of tumour and plasma circulating circulating-tumour DNA (ctDNA) among patients with PIK3CA-mutant HR + metastatic BC, who participated in a phase I/II dose-escalation study of alpelisib in combination with aromatase inhibitors (letrozole or exemestane).8 The most frequent grade 3 adverse event of was a dose-dependent maculopapular rash.