Study of Vintafolide (MK-8109, EC145) in Participants With Advanced Ovarian and Endometrial Cancers (MK-8109-007, EC-FV-02)

Part A: Inclusion Criteria: * Radiographic evidence of measurable disease (by Response Evaluation Criteria In Solid Tumors \[RECIST\]) and either: * Advanced epithelial ovarian cancer with serous or endometrioid histology, as confirmed by previous biopsy or, * ertafolide scan positive ovarian cancer, primary peritoneal cancer or adenocarcinoma of the endometrium. * Prior treatment with platinum and/or taxane compounds. * Eastern Cooperative Oncology Group (ECOG) Performance status of 0-2. * At least 4 weeks from prior therapy and recovered from associated acute toxicities. * Adequate bone marrow reserve, renal, and hepatic function. * Negative serum pregnancy test for women of childbearing potential and willingness to practice contraceptive methods. Exclusion Criteria: * Serious comorbidities (as determined by the Principal Investigator). * Women who are pregnant or lactating. * Symptomatic central nervous system (CNS) metastasis. * Prior radiation therapy to assessable disease, unless disease progression is confirmed at that site. * Requires palliative radiotherapy at time of study entry. * Unable to tolerate conditions for radionuclide imaging. * Other concurrent chemotherapy, immunotherapy, radiotherapy, or any ancillary therapy considered investigational. * Those who have been administered another radiopharmaceutical that would interfere with the assessment of 99mTc-ertafolide scan. Part B: Inclusion Criteria: * Radiographic evidence of measurable disease (by RECIST criteria) * ertafolide scan positive recurrent or persistent epithelial ovarian, primary fallopian tube, or peritoneal cancer. * Prior treatment with platinum compounds, but not more than 4 prior cytotoxic chemotheraputic regimens. * ECOG Performance status of 0-2. * At least 3 weeks from prior cytotoxic therapy and recovered from associated acute toxicities. * Adequate bone marrow reserve, renal, and hepatic function. * Negative serum pregnancy test for women of childbearing potential and willingness to practice contraceptive methods. Exclusion Criteria: * Serious comorbidities (as determined by the Principal Investigator). * Women who are pregnant or lactating. * Symptomatic CNS metastasis. * Other concurrent chemotherapy, immunotherapy, radiotherapy, or any ancillary therapy considered investigational. * Those who have had prior therapy with Vinorelbine or vinca-containing compounds.