Another agent, AZD4547, specifically inhibits FGFR1 to 3 and is currently being investigated in ongoing phase I/II trials in patients with advanced HR+ breast cancer after exposure to non-steroidal aromatase inhibitors (NCT01791985), initially in combination with exemestane and posteriorly, after the results of the BOLERO-2 study, with fulvestrant. This evidence concerns the gene CYP19A1 and breast cancer.