Inclusion Criteria:

          -  Men and women, aged 18 or older.

          -  Willingness to provide written informed consent for the study.

          -  Phase 1: Participants with locally advanced or metastatic solid tumors for which a
             PD-1 inhibitor is indicated (locally advanced disease must not be amenable to
             resection with curative intent) that have failed a PD-1/PD-L1 inhibitor therapy.

             a. PD should be based on imaging done at least 4 weeks apart.

          -  Phase 2: Participants with histologically confirmed recurrent Stage III and Stage IV
             melanoma who relapsed during therapy with anti-PD-1 given as adjuvant therapy.

               1. Participants should have no more than one prior therapy given as adjuvant
                  treatment.

               2. Participants in Stage 1 (n = 13) and Stage 2 (n = 21) of Phase 2 should have
                  documented LAG-3 positive expression (≥ 5%) by IHC.

               3. Participants should be documented BRAF mutation negative.

          -  Participants must have fresh biopsy available after completing adjuvant therapy or be
             willing and able to safely undergo pretreatment tumor biopsies (core or excisional).

          -  ECOG performance status 0 or 1.

          -  Willingness to avoid pregnancy or fathering children

        Exclusion Criteria:

          -  Laboratory and medical history parameters outside the protocol-defined range.

          -  Known hypersensitivity or severe reaction to any component of the study drugs or
             formulation components ) within 14 days before study Day 1.

          -  Administration of colony-stimulating factors within 14 days before study Day 1.

          -  Receipt of a live vaccine within 30 days of planned start of study treatment.

          -  Receipt of anticancer medications or investigational drugs within the following
             intervals before the first administration of study treatment

          -  Phase 1:

               1. ≤ 14 days for chemotherapy, targeted small molecule therapy, or radiation
                  therapy. Participants must also not require chronic use of corticosteroids and
                  must not have had radiation pneumonitis as a result of treatment. A 1-week
                  washout is permitted for palliative radiation to non-CNS disease with medical
                  monitor approval.

               2. ≤ 14 days and resolution of all associated toxicities for prior immunotherapy or
                  persistence of active cellular therapy c. < 14 days for prior PD-1
                  pathway-targeted agents (for Phase 1 and Phase 2).

             d. ≤ 28 days for a prior mAb used for anticancer therapy with the exception of PD-1
             pathway-targeted agents and denosumab.

             e. ≤ 7 days for immune-suppressive-based treatment for any reason. f. ≤ 28 days or 5
             half-lives (whichever is longer) before the first dose for all other investigational
             agents or devices. For investigational agents with long half-lives (eg, > 5 days),
             enrollment before the fifth half-life requires medical monitor approval.

             g. Has not recovered to ≤ Grade 1 from toxic effects of prior therapy (including prior
             immunotherapy) and/or complications from prior surgical intervention before starting
             therapy.

          -  Phase 2:

               1. Receipt of any anticancer medication other than adjuvant anti-PD-1 therapy.

               2. Receipt of PD-1 pathway-targeted inhibitors within 14 days before the first
                  administration of study treatment.

               3. Unknown LAG-3 status or LAG-3 positive > 0% but < 5%