A Study of DKN-01 in Combination With Paclitaxel or Pembrolizumab

Inclusion Criteria: In advanced esophagogastric malignancies: * Participants with histologically confirmed recurrent or metastatic esophageal or gastro-esophageal junction squamous cell or adenocarcinoma or gastric adenocarcinoma with Wnt Signaling Alterations * Participants must be refractory or intolerant to at least one prior therapy(ies) for metastatic or locally advanced disease * If prior therapy consisted of palliative chemoradiation therapy, it will be considered one line of therapy * Prior treatment with paclitaxel as part of a definitive therapy regimen is acceptable. Patients who are unable to receive paclitaxel for any reason will be allowed to receive DKN-01 as a single agent. * Prior treatment anti- programmed death-1 (PD-1)/ anti-PD-ligand 1 (PD-L1) monoclonal antibody (mAb) is permitted in patients provided the patient's disease is primary refractory, and the patient is not intolerant of pembrolizumab. Patients who are not eligible to receive pembrolizumab will be allowed to receive single agent DKN-01 * Tumor tissue for mandatory evaluation * Must have one or more tumors measurable on radiographic imaging as defined by the Response Evaluation Criteria in Solid Tumors (RECIST). Patients with evaluable but not measurable disease per RECIST criteria may be enrolled with the approval of the medical monitor. * Must be ≥18 years of age * Performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) scale. A performance status of 2 on the EC…