The patient must have histologically confirmed, gastric carcinoma, including gastroesophageal junction (GEJ) adenocarcinoma (patients with adenocarcinoma of the distal esophagus are eligible if the primary tumor involves the GEJ) Patients must have a histologic diagnosis of adenocarcinoma of the esophagus, gastroesophageal junction (GEJ), or gastric cardia (GC) based on biopsy material or adequate cytologic exam; tumors of the GC are defined as originating within cm of the GEJ Received any chemotherapy (including irinotecan) other than platinum and fluoropyrimidine with or without anthracycline or taxane for advanced gastric or GEJ adenocarcinoma Cohort : HER IHC +/FISH negative gastric/GEJ cancer HER IHC + or + FISH+ or FISH- gastric/GEJ cancer patients who have received at least and no more than prior systemic chemotherapy regimens. Participants with histologically or cytologically confirmed diagnosis of adenocarcinoma of the GEJ or stomach will be enrolled in this study Locally advanced or metastatic BC that has relapsed or is refractory to established therapies HER-Expressing Gastric/Gastroesophageal (GEJ) Cancer-Specific Inclusion Criteria Pathologically confirmed adenocarcinoma of the esophagus, GEJ or stomach. Subject has histologically confirmed diagnosis of Gastric or GEJ adenocarcinoma. Subject has a HER-Negative tumor as determined by local or central testing on a gastric or GEJ tumor specimen. The participant has a diagnosis of gastric or GEJ adenocarcinoma. Has histologically- or cytologically-confirmed diagnosis of locally advanced unresectable or metastatic gastric or GEJ adenocarcinoma Subjects with histologically confirmed unresectable locally advanced or metastatic adenocarcinoma of the stomach or gastro-esophageal junction (GEJ) Prior chemotherapy for unresectable locally advanced or metastatic adenocarcinoma of the stomach or gastro-esophageal junction (GEJ) RCC (clear cell), urothelial carcinoma (transitional cell), gastric or gastro-esophageal junctional (GEJ) adenocarcinoma, or K-RAS or N-RAS wild-type EGFR expressing CRC For gastric or GEJ adenocarcinoma: For urothelial carcinoma, gastric or GEJ adenocarcinoma, and CRC, platelet count ?, cells/mm For RCC, urothelial carcinoma, and gastric or GEJ adenocarcinoma, hemoglobin ?. g/dL For gastric or GEJ adenocarcinoma, prior treatment with any taxane Phase : Subjects with advanced or metastatic endometrial cancer, gastric cancer (including stomach, esophageal, and GEJ), and SCCHN. Histologically-confirmed gastric or GEJ adenocarcinoma (Siewert type II/III classification) Or Has histopathologically confirmed gastric or GEJ adenocarcinoma with documented disease progression after - prior lines of systemic therapy Has histopathologically confirmed gastric or GEJ adenocarcinoma with documented disease progression after - prior lines of systemic therapy The participant received > line of prior therapy for the treatment of locally advanced and unresectable or metastatic gastric or GEJ (Siewert Types I-III) adenocarcinoma. Gastric, GEJ or esophageal adenocarcinoma for which treatment with FOLFOX, CAPOX, FOLFIRI, or irinotecan would be acceptable as determined by the Investigator. Histologically confirmed metastatic adenocarcinoma of the stomach or GEJ Patients must have histologically or cytologically confirmed metastatic or unresectable gastric or gastroesophageal junction (GEJ) adenocarcinoma; GEJ adenocarcinoma may be classified according to Siewerts classification type I, II, or III Part F - Histologically- or cytologically-confirmed gastric carcinoma, including gastric adenocarcinoma or gastroesophageal junction (GEJ) adenocarcinoma (participants with adenocarcinoma of the distal esophagus are eligible if the primary tumor involves the GEJ). Participants must be ramucirumab nave. Participants must be, in the opinion of the investigator, an appropriate candidate for experimental therapy. human epidermal growth factor receptor (HER)/neu status should be documented, if known. Have a histologically or cytologically-confirmed diagnosis of adenocarcinoma of the GEJ or stomach Disease must be clinically limited to the esophagus or GEJ; GEJ tumors must be Siewert type I-III Histologically or cytologically confirmed locally mEC or metastatic adenocarcinoma of the GEJ Siewert Classification Type I in participants who have not received prior systemic therapy for primary and metastatic disease or chemoradiation therapy for primary disease Has previously untreated localized gastric or GEJ adenocarcinoma as defined by T or greater primary lesion or the presence of any positive nodes - N+ (clinical nodes) without evidence of metastatic disease.