More recently, a phase Ib trial including 23 patients with ER+/HER2- FGFR1 amplified metastatic BC previously exposed to CDK 4/6-inhibitors, combined erdafitinib with fulvestrant and palbociclib and showed a median PFS of only 3 months and a clinical benefit rate (CBR: complete response, partial response, or stable disease) of 28% at 6 months (100). This evidence concerns the gene ESR1 and breast cancer.