Inclusion Criteria:

          -  Histologically and/or cytologically proven unresectable locally advanced or metastatic
             tumors that express B7-H3 on the membrane or vasculature. The requirement for previous
             systemic therapy may be waived if a person was intolerant of standard front-line
             therapy

          -  Dose escalation phase prior systemic treatment requirements:

          -  pleural mesothelioma, pancreatic cancer: 1-3 prior treatments

          -  urothelial, SCHNN, prostate, soft tissue sarcoma, prostate cancer, TNBC, ccRCC, NSCLC:
             1-5 prior treatments

          -  ovarian cancer: 2-4 prior treatments

          -  colon cancer: 2-4 prior treatments

          -  cutaneous melanoma: at least 1 prior treatment (including immunotherapy).

          -  Patients with prior immune checkpoint inhibitors must have related toxicities reduced
             to Grade 0, 1, or baseline

          -  Measurable disease per RECIST 1.1 criteria

          -  Easter Cooperative Oncology Group (ECOG) performance status 0 or 1

          -  Acceptable laboratory parameters and adequate organ reserve.

        Exclusion Criteria:

          -  Patients with central nervous system (CNS) involvement must have been treated, be
             asymptomatic, do not exhibit progression of CNS metastases on MRI or CT within 28
             days, and do not have concurrent leptomeningeal disease or cord compression.

          -  Clinically significant pulmonary compromise within 28 days of first dose, including
             pneumonia, pneumonitis, requirement for supplemental oxygen). use to maintain adequate
             oxygenation, or pleural effusion sufficient to warrant pleurocentesis or any history
             of ≥ Grade 3 drug induced or radiation pneumonitis.

          -  History of autoimmune disease with certain exceptions such as vitiligo, resolved
             childhood atopic dermatitis, psoriasis not requiring systemic therapy within the past
             2 years, patients with history of Hashimoto's or Grave's disease that are now
             euthyroid clinically and by lab testing

          -  History of clinically-significant cardiovascular disease, or cardiac arrhythmias,
             including atrial fibrillation at screening or day of treatment

          -  History of clinically-significant gastrointestinal (GI) disease; GI perforation within
             1 year; GI bleeding or acute pancreatitis within 3 months; or diverticulitis within 4
             weeks of first study drug administration

          -  Active viral, bacterial, or systemic fungal infection requiring parenteral treatment
             within 7 days of first study drug administration

          -  Known history of hepatitis B or C infection or known positive test for hepatitis B
             surface antigen or core antigen, or hepatitis C polymerase chain reaction (PCR)

          -  Known positive testing for human immunodeficiency virus or history of acquired immune
             deficiency syndrome

          -  History of allogeneic bone marrow, stem cell, or solid organ transplant

          -  Treatment with systemic cancer therapy or investigational therapy within 3 weeks of
             first study drug administration; radiation within 2 weeks; corticosteroids (greater
             than or equal to 10 mg prednisone or equivalent per day) or other immune suppressive
             drugs within 2 weeks of first study drug administration

          -  Trauma or major surgery within 4 weeks of first study drug administration

          -  Known hypersensitivity to recombinant proteins, polysorbate 80, or any excipient
             contained in the drug or vehicle formulation for MGD009