A Phase 1/2 Study of VX15/2503 (IND# 136181), Children, Adolescents, or Young Adults with Recurrent or Relapsed Solid Tumors

This phase I/II trial studies the side effects and best dose of pepinemab and to see how well
it works in treating younger patients with solid tumors that have come back after treatment,
or do not respond to treatment. Immunotherapy with monoclonal antibodies, such as pepinemab,
may help the body's immune system attack the cancer, and may interfere with the ability of
tumor cells to grow and spread.

Inclusion Criteria:

- Part A: Patients with recurrent or refractory solid tumors are eligible, excluding
central nervous system (CNS) tumors; patients must have had histologic verification of
malignancy at original diagnosis or relapse

- Part B: Patients with recurrent or refractory osteosarcoma are eligible; patients must
have had histologic verification of malignancy at original diagnosis or relapse

- Part A: Patients must have either measurable or evaluable disease

- Part B: Patients must have measurable disease

- Patient's current disease state must be one for which there is no known curative
therapy or therapy proven to prolong survival with an acceptable quality of life

- Karnofsky >= 50% for patients > 16 years of age and Lansky >= 50 for patients =< 16
years of age; 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

- Patients must have fully recovered from the acute toxic effects of all prior
anti-cancer therapy and must meet the following minimum duration from prior
anti-cancer directed therapy prior to enrollment; if after the required timeframe, the
numerical eligibility criteria are met, e.g. blood count criteria, the patient is
considered to have recovered adequately

- Cytotoxic chemotherapy or other anti-cancer agents known to be myelosuppressive

- >= 21 days after the last dose of cytotoxic or myelosuppressive chemotherapy
(42 days if prior nitrosourea)

- Anti-cancer agents not known to be myelosuppressive (e.g. not associated with
reduced platelet or absolute neutrophil count [ANC] counts): >= 7 days after the
last dose of agent

- Antibodies: >= 21 days must have elapsed from infusion of last dose of antibody,
and toxicity related to prior antibody therapy must be recovered to grade =< 1

- Corticosteroids: If used to modify immune adverse events related to prior
therapy, >= 14 days must have elapsed since last dose of corticosteroid

- Hematopoietic growth factors: >= 14 days after the last dose of a long-acting
growth factor (e.g. pegfilgrastim) or 7 days for short-acting growth factor; for
agents that have known adverse events occurring beyond 7 days after
administration, this period must be extended beyond the time during which adverse
events are known to occur; the duration of this interval must be discussed with
the study chair and the study-assigned research coordinator

- Interleukins, interferons and cytokines (other than hematopoietic growth
factors): >= 21 days after the completion of interleukins, interferon or
cytokines (other than hematopoietic growth factors)

- Stem cell Infusions (with or without total body irradiation [TBI]):

- Allogeneic (non-autologous) bone marrow or stem cell transplant, or any stem
cell infusion including donor lymphocyte infusion (DLI) or boost infusion:
>= 84 days after infusion and no evidence of graft versus host disease
(GVHD)

- Autologous stem cell infusion including boost infusion: >= 42 days

- Cellular Therapy: >= 42 days after the completion of any type of cellular therapy
(e.g. modified T cells, natural killer [NK] cells, dendritic cells, etc.)

- Radiation Therapy (XRT)/External Beam Irradiation including Protons: >= 14 days
after local XRT; >= 150 days after TBI, craniospinal XRT or if radiation to >=
50% of the pelvis; >= 42 days if other substantial bone marrow (BM) radiation

- Radiopharmaceutical therapy (e.g., radiolabeled antibody, 131I-MIBG): >= 42 days
after systemically administered radiopharmaceutical therapy

- Patients must not have received prior exposure to VX15/2503

- Peripheral absolute neutrophil count (ANC) >= 1000/mm^3

- Platelet count >= 100,000/mm^3 (transfusion independent, defined as not receiving
platelet transfusions for at least 7 days prior to enrollment)

- Hemoglobin >= 8.0 g/dL at baseline (may receive red blood cell [RBC] transfusions)

- Patients with known bone marrow metastatic disease will be eligible for study provided
they meet the blood counts above (may receive transfusions provided they are not known
to be refractory to red cell or platelet transfusions); these patients will not be
evaluable for hematologic toxicity; at least 5 of every cohort of 6 patients must be
evaluable for hematologic toxicity for the dose-escalation part of the study; if
dose-limiting hematologic toxicity is observed, all subsequent patients enrolled must
be evaluable for hematologic toxicity

- Creatinine clearance or radioisotope glomerular filtration rate (GFR) >= 70
ml/min/1.73 m^2 or

- A serum creatinine based on age/gender as follows:

- Age: 1 to < 2 years; Male: 0.6 mg/dL; Female: 0.6 mg/dL

- Age: 2 to < 6 years; Male: 0.8 mg/dL; Female: 0.8 mg/dL

- Age: 6 to < 10 years; Male: 1 mg/dL; Female: 1 mg/dL

- Age: 10 to < 13 years; Male: 1.2 mg/dL; Female: 1.2 mg/dL

- Age: 13 to < 16 years; Male: 1.5 mg/dL; Female: 1.4 mg/dL

- Age: >= 16 years; Male: 1.7 mg/dL; Female: 1.4 mg/dL

- Bilirubin (sum of conjugated + unconjugated) =< 1.5 x upper limit of normal (ULN) for
age

- Alanine aminotransferase (ALT) serum glutamic pyruvic transaminase (SGPT) =< 135 U/L;
for the purpose of this study, the ULN for ALT is 45 U/L

- Serum albumin >= 2 g/dL

- No clinical indications such as evidence of dyspnea at rest, or exercise intolerance
due to pulmonary insufficiency

- If clinical indications, pulse oximetry > 94% on room air

- All patients and/or their parents or legally authorized representatives must sign a
written informed consent; assent, when appropriate, will be obtained according to
institutional guidelines

- Tissue blocks or slides must be sent; if tissue blocks or slides are unavailable, the
study chair must be notified prior to enrollment

Exclusion Criteria:

- Pregnant or breast-feeding women will not be entered on this study; pregnancy tests
must be obtained in girls who are post-menarchal; males or females of reproductive
potential may not participate unless they have agreed to use two effective methods of
birth control, including a medically accepted barrier or contraceptive method (e.g.,
male or female condom) for the duration of the study; abstinence is an acceptable
method of birth control

- Patients receiving systemic corticosteroids who have not been on a stable or
decreasing dose of corticosteroid for at least 7 days prior to enrollment are not
eligible; if used to modify immune adverse events related to prior therapy, >= 14 days
must have elapsed since last dose of systemic corticosteroid; Note: patients who are
using topical or inhaled corticosteroids are eligible

- Patients who are currently receiving another investigational drug are not eligible

- Patients who are currently receiving other anti-cancer agents are not eligible (except
leukemia patients receiving hydroxyurea, which may be continued until 24 hours prior
to start of protocol therapy)

- Patients who are receiving cyclosporine, tacrolimus or other agents to prevent
graft-versus-host disease post bone marrow transplant are not eligible for this trial

- Patients who have an uncontrolled infection are not eligible

- Patients who have received a prior solid organ transplantation are not eligible

- Patients who in the opinion of the investigator may not be able to comply with the
safety monitoring requirements of the study are not eligible