© 2018 2018 KN Moore. Mirvetuximab soravtansine, an antibody-drug conjugate that binds with high affinity to folate receptor-α to provide tumor-directed delivery of the potent microtubule-disrupting agent DM4, has emerged as a promising investigational agent for the treatment of ovarian cancer, particularly in the setting of platinum-resistant disease. Here we describe the rationale and design of FORWARD I (NCT02631876), the first randomized, multicenter Phase III study to compare the safety and efficacy of mirvetuximab soravtansine versus investigator's choice of chemotherapy in women with folate receptor-α-positive, platinum-resistant epithelial ovarian, primary peritoneal or fallopian tube cancer. Patients will be randomized in a 2:1 ratio. The primary end point is progression-free survival, and key secondary objectives include comparison of overall response rates, overall survival and duration of response.