Inclusion Criteria:  Must have locally advanced or metastatic disease that is refractory to standard therapy, or for which no standard therapy is judged to be appropriate or provide clinical benefit, as judged by the Investigator Must have a histologically or cytologically confirmed malignant solid tumor associated with Nectin-4 expression, including urothelial (transitional cell) carcinoma; head and neck squamous cell carcinoma; non-small cell lung cancer; and ovarian, breast, gastric, or esophageal carcinoma Must have ECOG performance status score 0 or 1 and acceptable organ and hematological function Must have radiographically documented metastatic or locally advanced disease per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 Life expectancy ≥12 weeks Must submit fresh or archival tumor tissue Must provide written informed consent, according to local guidelines, signed and dated by the patient or by a legal guardian prior to the performance of any study-specific procedures, sampling, or analysis  Exclusion Criteria:  Prior therapy with a cytotoxic, small molecule, or other systemic chemotherapy within 14 days of the first dose of study drug Prior immunotherapy, including monoclonal antibodies, within 28 days or 5 half-lives of the first dose of study drug, whichever is shorter Prior treatment with CD137 targeted therapy Body mass index greater than or equal to 35 kg/m2 Mean resting QTc (eg, QTcF) greater than 470 msec on triplicate electrocardiograms (ECGs) obtained at screening Uncontrolled symptomatic brain metastases Uncontrolled diabetes with glycosylated hemoglobin greater than or equal to 8% Uncontrolled hypertension at screening or prior to initiation of study drug History of autoimmune disease except well-controlled diabetes mellitus, alopecia, well controlled thyroid disease or vitiligo