Inclusion Criteria:

          -  For Part A, the subject has histological or cytological evidence of a solid tumor; for
             Part B, the subject has a diagnosis of melanoma or renal cell carcinoma

          -  All subjects must have advanced solid tumors that have returned after treatment with
             established approved therapies or be intolerant of established therapies

          -  Subjects enrolled in Part B or Part C must have at least 1 lesion that may qualify as
             a target lesion

          -  Subject can move around on their own, has an Eastern Cooperative Oncology Group (ECOG)
             performance status of 0 or 1, and has an estimated life expectancy of at least 3
             months

          -  Subject must have adequate hematologic reserve

          -  Subjects must have adequate liver function

          -  Subjects must have adequate kidney function

          -  Subjects must be recovered from the effects of any prior chemotherapy, immunotherapy,
             other prior systemic anticancer therapy, radiotherapy or surgery

          -  Subjects who have received investigational agents must wait at least 4 weeks

          -  Females of childbearing potential must have a negative pregnancy test within 7 days of
             the start of treatment and on Day 1 before the first dose is administered. A female
             not of childbearing potential is one who has undergone bilateral oophorectomies or who
             is postmenopausal, defined as >45 years of age and without a menstrual period for 12
             consecutive months

          -  Meets contraceptive requirements defined in the protocol

          -  Additional criteria may apply

        Exclusion Criteria:

          -  Subject is currently pregnant or breastfeeding, or is planning to become pregnant
             during the study

          -  Subjects with an active infection or with a fever >/= 38.5 degrees C within 3 days of
             the first scheduled day of dosing for Cycle 1

          -  Subjects with active or symptomatic central nervous system metastases are excluded.
             Subjects with central nervous system metastases are eligible for the study if the
             metastases have been treated by surgery and/or radiation therapy, the subject is off
             corticosteroids for at least 2 weeks and the subject is neurologically stable

          -  Subjects have a mean QT interval corrected by the Fridericia Correction formula value
             of >470 msec (in females) or >450 msec (in males)

          -  Subjects with known hypersensitivity to any components of ALKS 4230

          -  Subjects with known hypersensitivity to any components of pembrolizumab (for patients
             in combination arm only)

          -  Subjects who require pharmacologic doses of corticosteroids; replacement doses,
             topical, ophthalmologic, and inhalational steroids are permitted

          -  Subjects who developed autoimmune disorders while on prior immunotherapy, including
             pneumonitis, nephritis, and neuropathy

          -  Subjects with any other concurrent uncontrolled illness, including mental illness or
             substance abuse, which may interfere with the ability of the subject to cooperate and
             participate in the study

          -  The subject is known to be positive for human immunodeficiency virus (HIV), hepatitis
             B or C, or active tuberculosis, or has a known history of tuberculosis

          -  Subjects with dyspnea at rest of requiring oxygen therapy

          -  Subjects active autoimmune disease requiring systemic treatment within the past 30
             days

          -  Subjects who received radiotherapy within the last 4 weeks before start of study
             treatment administration with the exception of limited field palliative radiotherapy

          -  Subjects who have received systemic immunomodulatory agents within 28 days prior to
             C1D1.

          -  Subjects who have received administration of a live, attenuated vaccine within 4 weeks
             of Cycle 1, Day1.

          -  Prior solid organ and/or non-autologous hematopoietic stem cell or bone marrow
             transplant recipients

          -  Subjects who have received prior IL-2 based or IL-15 based cytokine therapy

          -  Additional criteria may apply