A Phase II Evaluation of the Safety and Efficacy of Mirvetuximab Soravtansine (IMGN853) in Women With Folate Receptor-α Positive Persistent or Recurrent Endometrial Cancer

Inclusion Criteria: * Radiologically confirmed (ie, CT scan and/or MRI) persistent or recurrent endometrial cancer * Patients must have one of the following pathologically documented, definitively diagnosed tumor types: Uterine serous carcinoma (Pure or Mixed), Grade 2 or Grade 3 endometrial adenocarcinoma, Carcinosarcoma with high grade serous or Grade 2/3 endometrioid components, or clear cell carcinoma (Pure or Mixed). * Have measurable disease * FRα-positive tumor expression as defined in the protocol * Have at least one "target lesion" to be used to assess response as defined by RECIST v1.1 * Patients must have received prior treatment with ≤ 3 prior lines of therapy for recurrent disease; hormonal agents are not considered a line of therapy; prior treatment with folate receptor-targeting investigational agents is not allowed * Have Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Time from prior therapy: Systemic anti-neoplastic therapy: five half-lives or four weeks, whichever is shorter; Radiotherapy: wide-field radiotherapy completed at least four weeks, or focal radiation completed at least two weeks, prior to starting study treatment * Patients must have resolution of toxic effect(s) of the most recent prior chemotherapy * Patients must have adequate hematologic, liver and kidney function as defined in the protocol * Women of child bearing potential (WCBP), must agree to use effective contraceptive methods during study treatment and for at least twelve weeks after the last dose of IMGN853 * WCBP must have a negative pregnancy test within 4 days prior to the first dose of study treatment * At time of initial surgery, patient may have either been optimally or suboptimally debulked * Have signed the informed consent form, and willing to adhere to the study visit schedule and other protocol requirements * ≥ 18 years of age Exclusion Criteria: * Active or chronic corneal disorder * Serious concurrent illness or clinically-relevant active infection as defined in the protocol * Clinically-significant cardiac disease such as recent myocardial infarction (≤ 6 months prior to day 1), unstable angina pectoris, uncontrolled congestive heart failure, uncontrolled hypertension, prior history of hypertensive crisis or hypertensive encephalopathy, uncontrolled cardiac arrhythmias, clinically-significant vascular disease, severe aortic stenosis, clinically significant peripheral vascular disease, or cardiac toxicity following prior chemotherapy * History of neurological conditions * History of hemorrhagic or ischemic stroke within the last 6 months * History of cirrhotic liver disease * Previous clinical diagnosis of non-infectious pneumonitis * Prior hypersensitivity to monoclonal antibodies * Women who are pregnant or breast feeding * Carcinomatous meningitis, untreated central nervous system (CNS) disease or symptomatic CNS metastasis * History or evidence of thrombotic or hemorrhagic disorders within 6 months before first study treatment * Required used of folate-containing supplements (e.g. folate deficiency) * Has a known additional malignancy that is progressing or required active treatment within 3 years of first dose of study treatment