Inclusion Criteria

- INCLUSION CRITERIA:

- Diagnosis:

- Histologically confirmed solid tumors, including primary brain tumors. In subjects
with brain stem or optic gliomas the requirement for histological confirmation may be
waived.

- Age: 2 to less than or equal to 25 years old at the time of enrollment.

- Patients must have evaluable or measurable malignant disease at enrollment.

- Prior Therapy:

- The patient's malignancy must have relapsed after or failed to respond to frontline
curative therapy and/or there must not be any potentially curative treatment options
available at the time of study entry.

- There is no limit to the number of prior treatment regimens. However, patients must
have fully recovered from the acute toxic effects of all prior chemotherapy,
immunotherapy, or radiotherapy prior to study enrollment. Acute toxicity of any
previous therapy must have resolved to grade 1 or less, unless specified elsewhere.

- Myelosuppressive chemotherapy: Patients must not have received myelosuppressive
chemotherapy within 3 weeks of enrollment (6 weeks if prior nitrosourea).

- Hematopoietic growth factors: At least 7 days must have elapsed since the completion
of therapy with a growth factor. At least 14 days must have elapsed after receiving
pegfilgrastim.

- Biologic (anti-neoplastic agent) or metronomic non-myelosuppressive chemotherapy: At
least 7 days must have elapsed since the completion of therapy with a biologic agent.
For agents that have known adverse events occurring beyond 7 days after
administration, this period prior to enrollment must be extended beyond the time
during which adverse events are known to occur.

- Monoclonal antibodies: At least 4 weeks must have elapsed since prior therapy that
included a monoclonal antibody.

- Radiotherapy: 3 weeks must have elapsed since XRT

- Performance status: ECOG 0, 1 or 2, or for children less than or equal to10 years of
age, Lansky greater than or equal to 60. Note: Patients who are unable to walk
because of paralysis, but who are up in a wheelchair, will be considered ambulatory
for the purpose of assessing the performance score.

- Cardiac function: Left ventricular ejection fraction greater than or equal to 45% or
fractional shortening greater than or equal to28%.

- Liver function: Serum total bilirubin < 2 mg/dl, serum AST and ALT less than or
equal to 3 x upper limit of normal. Patients with Gilbert syndrome are excluded from
the requirement of a normal

bilirubin. (Gilbert syndrome is found in 3-10% of the general population, and is
characterized by mild, chronic unconjugated hyperbilirubinemia in the absence of liver
disease or overt hemolysis). On cohort B, patients with liver involvement by tumor will
not be eligible due to potential confounding risk for hepatotoxicity when rhIL15 is
administered. NOTE: adult values will be used for calculating hepatic toxicity on this
trial, as is standard on POB phase I trials.

- Renal function: Age-adjusted normal serum creatinine according to the following table or
a creatinine clearance greater than or equal to 60 ml/min/1.73 m(2).

Age (years) Maximum serum creatinine (mg/dl)

less than or equal to5 0.8

> 5 less than or equal to 10 1.0

> 10 less than or equal to 15 1.2

> 15 1.5

- Marrow function: ANC must be > 750/mm(3) (unless due to underlying disease in which
case there is no grade restriction), platelet count must be greater than or equal to
75,000/mm(3) (not achieved by transfusion). Lymphopenia, CD4 lymphopenia, leukopenia,
and anemia will not render patients ineligible.

- Female patients (and when relevant their male partners) must be willing to practice
birth control (including abstinence) during and for two months after treatment, if of
childbearing potential.

- Ability to give informed consent. For patients < 18 years of age their legal guardian
must give informed consent. Pediatric patients will be included in age-appropriate
discussion in order to obtain verbal assent.

- Durable power of attorney form completed (patients greater than or equal to18 years
of age only).

EXCLUSION CRITERIA:

- Untreated CNS metastatic disease as defined by:

- Solid Tumors: History of untreated metastatic CNS tumor involvement. Extradural
masses which have not invaded the brain parenchyma or parameningeal tumors without
evidence for leptomeningeal spread will not render the patient ineligible. Patients
with previous CNS tumor involvement are eligible IF the CNS tumor(s) has been treated
and has been stable or resolving for at least 4 weeks; and if the patient does not
currently require steroids.

- Prior history allogeneic stem cell transplantation.

- Breast feeding or pregnant females (due to risk to fetus or newborn).

- HIV or HTLV-I/II (due to unacceptable risk associated with severe immune suppression
and risk associated with cell products).

- Hepatitis B surface antigen (HBsAg) positive or hepatitis C antibody positive with
elevated liver transaminases. All patients with chronic active hepatitis (including
those on antiviral therapy) are ineligible.

- Patients who require systemic corticosteroid or other systemic immunosuppressive
therapy. Immunosuppressive therapy must be stopped at least 28 days prior to
enrollment. Topical agents and/or inhaled corticosteroids are permitted.

- High risk of inability to comply with therapy in the estimation of the PI.

- Clinically significant systemic illness (e.g. serious active infections or
significant vital other organ dysfunction), that in the judgment of the PI would
likely compromise the patient's ability to tolerate protocol therapy or significantly
increase the risk of complications.

INCLUSION OF WOMEN AND MINORITIES:

Both men and women of all races and ethnic groups are eligible for this trial.