-  INCLUSION CRITERIA:

        Subjects must have histologically confirmed solid tumor malignancy that is metastatic or
        treatment refractory cancers which are not curable or do not have known measures or
        treatments that are associated with a survival advantage (as defined by the subject or the
        physician investigator). Enrollment of subjects with tumors that can be safely biopsied is
        encouraged.

        Subjects must have evaluable, or measurable disease defined as greater than or equal to 1
        lesion that can be accurately measured in greater than or equal to 1 dimension (longest
        diameter to be recorded for non-nodal lesions and short axis for nodal lesions) as greater
        than or equal to 20 mm with conventional techniques or as greater than or equal to 10 mm
        with a spiral computed tomography (CT) scan.

        Subjects must have recovered to less than or equal to grade 1 NCI Common Terminology
        Criteria for Adverse Events (CTCAE) or stabilized from toxicity of prior chemotherapy or
        biologic therapy administered more than 4 weeks or 5 half-lives earlier, whichever is
        shorter.

        Subjects on bisphosphonates/denosumab for any cancer or on hormone therapy for prostate
        cancer may continue this therapy. However, subjects with prostate cancer must have
        confirmed metastatic disease that has progressed despite hormonal therapy or refused or is
        intolerant of hormonal therapy.

        Age greater than or equal to 18 years.

        ECOG performance status less than or equal to 2 (Karnofsky or Lansky greater than or equal
        to 70%.

        Subjects must have normal organ and marrow function as defined below:

          -  leukocytes greater than or equal to 2,000/mm^3

          -  absolute neutrophil count (ANC) greater than or equal 1,500/mm^3

          -  platelets greater than or equal to 100,000/mm^3

          -  total bilirubin less than or equal to 1.5 times institutional upper limit of normal
             (ULN)

          -  AST/ALT less than or equal to 1.5 times institutional upper limit of normal (ULN) or
             if liver metastasis, less than or equal to 2.5 times ULN

          -  Serum creatinine less than or equal to 1.5 times institutional ULN, OR Creatinine
             clearance greater than or equal to 50 mL/min/1.73 m2 for subjects with serum
             creatinine levels greater than 1.5 times higher than institutional normal

        DLCO/VA and FEV1 greater than or equal to 50% of predicted on pulmonary function tests
        (subjects must have pulmonary function tests performed to be eligible)

        Subjects with inactive central nervous system (CNS) metastasis are eligible. Inactive CNS
        metastasis is defined as: no symptoms of brain metastases after successful definitive
        treatment of brain metastases (surgical resection, whole brain irradiation, stereotactic
        radiation therapy, or a combination of these) with stable or improved radiographic
        appearance on magnetic resonance imaging (MRI) scan at least 1 month after completion of
        treatment.

        Subjects may have previously progressed on treatment with one of the 3 agents being used in
        this trial or treatment with other checkpoint inhibitors, as long as they have recovered
        from previous toxicity. Subjects that previously progressed on treatment with a combination
        of any 2 of the 3 agents being used in this trial are eligible for the triplet cohort only.

        The effects of ipilimumab, nivolumab, and rhIL-15 on the developing human fetus are
        unknown. For this reason, women of child-bearing potential and men must agree to use
        adequate contraception (hormonal or barrier method of birth control; abstinence) prior to
        study entry, during the treatment portion of the study, and for a minimum for 5 months
        (women) and 7 months (men) after the last dose of study drug. Should a woman become
        pregnant or suspect she is pregnant while she or her partner is participating in this
        study, she should inform her treating physician immediately.

        Ability to understand and the willingness to sign a written informed consent document.

        Willingness to provide blood and biopsy samples for research purposes if on the expansion
        phase of the study.

        EXCLUSION CRITERIA:

        Subjects who have received any prior cytotoxic therapy, immunotherapy, major surgery,
        antitumor vaccines or monoclonal antibodies in the 4 weeks or 5 halflives, whichever is
        shorter, prior to C1D1 (6 weeks prior for checkpoint inhibitors such as anti-CTLA-4 or
        anti-PD1/PD-L1 and for nitrosoureas or mitomycin C). Subjects must not have received
        radiotherapy in the 2 weeks prior to C1D1. Subjects who had grade greater than or equal to3
        irAE during previous treatment with one of the checkpoint inhibitors are excluded from the
        trial; subjects who had grade 1 or 2 irAE that have resolved to grade 1 are eligible.

        Subjects with primary brain cancers or active CNS metastases should be excluded from this
        clinical trial because of their poor prognosis and because they often develop progressive
        neurologic dysfunction that would confound the evaluation of neurologic and other adverse
        events.

        History of allergic reactions attributed to compounds of similar chemical or biologic
        composition to any of the agents on this trial.

        Concurrent anticancer therapy (including other investigational agents) with the exception
        of hormone therapy for breast or prostate cancer. Patients that have received treatment for
        a different cancer previously and have been disease-free for less than one year are
        excluded.

        Uncontrolled intercurrent illness including, but not limited to, ongoing or active
        infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
        arrhythmia, cognitive impairment, active substance abuse, or psychiatric illness/social
        situations that, in the view of the Investigator, would preclude safe treatment or the
        ability to give informed consent and limit compliance with study requirements.

        Inability or refusal to practice effective contraception during therapy or the presence of
        pregnancy or active breastfeeding. Because there is no significant preclinical information
        regarding the risk to a fetus or newborn infant, pregnant or breastfeeding women will be
        excluded from participation in this trial.

        Documented HIV infection or positive serology, active bacterial infections, serologic or
        PCR evidence for active or chronic hepatitis B or hepatitis C. Since rhIL-15 treatment
        stimulates the subjects immune system to attack their tumor, the defective immune systems
        of subjects with HIV or hepatitis B or hepatitis C makes responses to this treatment much
        less likely to provide benefit and these subjects are not eligible for this trial.

        History of severe asthma (subjects with a history of mild asthma that are on or can be
        switched to non-corticosteroid

        bronchodilator regimens are eligible).

        Patients with active autoimmune disease or history of autoimmune disease that might recur,
        which may affect vital organ function or require immune suppressive treatment including
        systemic corticosteroids, should be excluded. The use of inhaled corticosteroids is
        allowed.