After these encouraging results in an initially unselected population, the phase 3 FORWARD I trial (ClinicalTrials.gov Identifier: NCT02631876) compared mirvetuximab soravtansine to chemotherapy according to the investigator’s choice (weekly paclitaxel, pegylated liposomal doxorubicin or topotecan) in platinum-resistant ovarian cancer with ≥50% of FRα expression assessed by the 10× method (percentage of stained cells in ≥10× magnification by immunochemistry). Here, FOLR1 is linked to ovarian cancer.