Inclusion Criteria:

          -  Locally advanced or metastatic disease; locally advanced disease must not be amenable
             to resection with curative intent.

          -  Phase 1: Subjects with advanced or metastatic solid tumors.

          -  Phase 1: Subjects who have disease progression after treatment with available
             therapies.

          -  Phase 2: Subjects with advanced or metastatic cervical cancer, gastric cancer
             (including stomach, esophageal, and GEJ), SCCHN, PD-1 refractory SCCHN and PD-1/PD-L1
             relapsed melanoma.

          -  Presence of measurable disease based on RECIST v1.1.

          -  Eastern Cooperative Oncology Group (ECOG) performance status 0 to 1.

        Exclusion Criteria:

          -  Laboratory and medical history parameters not within the Protocol-defined range

          -  Prior treatment with any tumor necrosis factor super family agonist.

          -  Receipt of anticancer medications or investigational drugs within protocol-defined
             intervals before the first administration of study drug.

          -  Has not recovered to ≤ Grade 1 from toxic effects of prior therapy.

          -  Active autoimmune disease.

          -  Known active central nervous system metastases and/or carcinomatous meningitis.

          -  Evidence of active, noninfectious pneumonitis or history of interstitial lung disease.

          -  Evidence of hepatitis B virus or hepatitis C virus infection or risk of reactivation.

          -  Known history of human immunodeficiency virus (HIV; HIV 1/2 antibodies).