Inclusion Criteria:

          1. Patients with histological diagnosis of endometrial carcinoma (including others per
             protocol).

          2. Expression of folate receptor alpha (FRα) on either archival tumor or new biopsy is
             required.

          3. Measurable disease

          4. Evidence that the endometrial cancer is advanced, recurrent, or persistent and has
             relapsed or is refractory to curative therapy or established treatments.

          5. At least 1 prior platinum-based chemotherapeutic regimen, but not more than 2 prior
             chemotherapeutic regimens, for management of endometrial carcinoma. Prior treatment
             may include chemotherapy, or chemotherapy/radiation therapy . Chemotherapy
             administered in conjunction with primary radiation as a radio-sensitized therapy will
             be considered a systemic chemotherapy regimen

          6. Female patients 18 years or older

          7. Eastern Cooperative Oncology Group performance status of 0 to 1;

          8. Patient must have archival tumor tissue available from the primary or recurrent cancer
             prior to first dose. If archival tumor sample is not available, tumor sample from new
             biopsy is acceptable.

          9. Patients must have acceptable organ and marrow function as defined per protocol

         10. Time from prior therapy:

               1. Systemic anti-neoplastic therapy: five half-lives or four weeks, whichever is
                  shorter. Hormonal therapy is not considered anti-neoplastic therapy.

               2. Radiotherapy: wide-field radiotherapy (e.g. > 30% of marrow-bearing bones)
                  completed at least four weeks, or focal radiation completed at least two weeks,
                  prior to starting study treatment

         11. Patients must have a life expectancy of at least 3 months

         12. Patients should have no major existing co-morbidities or medical conditions that will
             preclude therapy

         13. Ability to understand and the willingness to sign a written informed consent document,
             and to comply with the requirements of the protocol; with the understanding that
             consent may be withdrawn by the patient at any time without prejudice to future
             medical care.

         14. Female patients of reproductive potential and their male partners must agree to
             practice 1 highly effective method of contraception and 1 additional effective
             (barrier) method at the same time, from the time of signing the informed consent
             through at least twelve weeks after the last dose of IMGN853 and/ or bevacizumab.

        Exclusion Criteria:

          1. Previous treatment with mirvetuximab.

          2. Invasive cancer within the past 2 years. Noninvasive non-melanoma skin cancers are not
             exclusions if they have undergone complete resection.

          3. Untreated or symptomatic central nervous system (CNS) metastases. Patients with
             asymptomatic CNS metastases are eligible provided they have been clinically stable for
             at least 4 weeks prior to first dose of study treatment), have no evidence of new or
             emerging CNS metastasis, and are not using steroids for at least 7 days prior to first
             dose of study treatment.

          4. Unstable angina or myocardial infarction within the previous 6 months; uncontrolled
             hypertension (defined as systolic blood pressure > 150 and/or diastolic blood pressure
             > 100 mmHg on antihypertensive medications); prior history of hypertensive crisis or
             hypertensive encephalopathy; symptomatic congestive heart failure (NYHA Class III and
             IV); uncontrolled cardiac arrhythmia; clinically-significant vascular disease (e.g.
             aortic aneurysm, or dissecting aneurysm), severe aortic stenosis; clinically
             significant peripheral vascular disease; history of any CNS cerebrovascular ischemia
             or stroke within the last 6 months.

          5. Active pulmonary disease or other coexisting medical condition that would preclude
             full compliance with the study.

          6. Receiving any other investigational agents.

          7. History of prior severe infusion reaction to a monoclonal antibody. Patients with
             known hypersensitivity of Chinese hamster ovary cell products or other recombinant
             human antibodies.

          8. Persisting ≥Grade 2 toxicity (except alopecia) from previous anti-cancer treatment.

          9. Patients with > Grade 1 peripheral neuropathy

         10. Active or chronic corneal disorder, including but not limited to the following:

               -  Sjogren's syndrome

               -  Fuchs corneal dystrophy (requiring treatment)

               -  History of corneal transplantation

               -  Active herpetic keratitis

               -  Active ocular conditions requiring on-going treatment/monitoring such as wet
                  age-related macular degeneration requiring intravitreal injections, active
                  diabetic retinopathy with macular edema, presence of papilledema, and monocular
                  vision.

         11. Serious concurrent illness or clinically-relevant active infection, including but not
             limited to the following:

               -  Known active hepatitis B or C

               -  Known Human Immunodeficiency Virus (HIV) infection

               -  Varicella-zoster virus (shingles)

               -  Cytomegalovirus infection

               -  Any other known concurrent infectious disease, requiring IV antibiotics within 2
                  weeks of study enrollment

         12. History of cirrhotic liver disease

         13. History or evidence of thrombotic or hemorrhagic disorders within 6 months before
             first study treatment

         14. Required used of folate-containing supplements (e.g. for folate deficiency)

         15. Pregnancy

         16. History of bowel obstruction (including subocclusive disease) related to underlying
             disease within 6 months of study treatment.

         17. Clinically-significant proteinuria defined per protocol