Trial of Heat Shock Protein Peptide Complex-96 (HSPPC-96) Vaccine

Immunotherapy for Brain Tumors:

Although it is usually ineffective alone, it has long been recognized that the immune system
of tumor bearing hosts (human and animal models) does, indeed, mount an endogenous
immune-mediated response to tumor. Unfortunately, this immune response alone is not
sufficient in combating tumor. The balance of immune response and immune regulation often
mitigates this anti-tumor response. Several mechanisms within tumor-bearing hosts compromise
the efficacy of this anti-tumor immune response, including low levels of expression of
co-stimulatory molecules such as the B7 family of immune-regulatory ligands, the tumor's
local production of immunosuppressive factors and the tumor's ability to over-express
pro-survival factors thus escaping destruction by the host immune system. However, many have
hypothesized that if this immune response can be better harnessed and/or magnified, there is
potential for heightened tumor responses.

A number of specific observations support the use of immunotherapy to treat brain tumors.
Data published supports a possible correlation between HIV mediated immunosuppression and the
development of intracranial glial tumors. Immunosuppression in transplant recipients has also
been implicated in the development of intracranial glioma. Further supporting this hypothesis
are documented rare cases of long-term remission of malignant brain tumors following
significant post-operative infection. These observations have fueled the idea that a
heightened immune system may confer some protection against intracranial tumors. With this in
mind, one hypothesis is that successful active immunotherapy for patients with brain tumors
will require development of a specific peptide or polyvalent vaccines in an effort to further
stimulate the host's immune system against specific tumor-associated antigens.

It has been well established that mice can be immunized against syngeneic tumors. Heat shock
protein-peptide complexes isolated from a specific tumor can been utilized to elicit both
prophylactic and therapeutic immunity against the specific cancer from which the preparations
have been isolated. Overexpression of heat shock protein-chaperone complexes (HSPPC) in brain
tumor cells suggests that HSPPC are a meaningful target antigen for a brain tumor vaccine.
Moreover, in addition to generating tumor-specific immunity, vaccination with heat shock
protein peptide complexes in animal models generates therapeutic responses. Since an immune
response has not been widely evaluated for pediatric brain tumors, this study will test the
safety and feasibility of producing and administering a vaccine capable of generating an
autologous, anti-tumor immune response.

HSPPC-96:

Heat shock proteins are up-regulated along with tissue-specific chaperone peptides in the
setting of cellular stress to prevent damage and aggregation of the proteome. Therefore, heat
shock protein peptide complexes (HSPPC) provide a cytoprotective effect. Overexpression of
heat shock proteins has been described in malignant glioma and medulloblastoma cells.
HSPPC-96 is an autologous tumor-derived vaccine that has been under clinical investigation
for the treatment of a variety of cancer types, including adult high-grade glioma (HGG). It
is composed of the 96-kilodalton (KDa) heat shock protein, glycoprotein 96 (gp96), attached
to autologous tumor-derived peptides. The gp96 glycoprotein in HSPPC-96 is a highly
conserved, abundant, non-polymorphic stress protein found in every cell type of the body.
Gp96 isolated from normal or tumor tissues is found in complex with peptides that are
specific to the original tissue. Mouse models have shown that HSPPC-96 confers protective
immunity only to the tumor from which it is derived and not to genetically distinct tumors or
normal tissue.

When injected into the host, HSPPC-96 interacts with antigen presenting cells (APCs) via
specific receptors. Once internalized by the APCs, the peptides chaperoned by the HSP are
transferred to major histocompatibility complex (MHC) class I and class II molecules in
intracellular compartments and eventually expressed at the cell surface. T-cells then
recognize the MHC-peptide complexes and are stimulated. HSP-peptide complexes are unique in
their ability to elicit an antigen-specific cytotoxic T-cell response. Additionally, cluster
of differentiation 4 (CD4+) T cells and natural killer (NK) cells are also recruited adding
to the tumor-associated immunity.

Some advantages of heat shock protein-peptide vaccines for immunotherapy are that it elicits
a cluster of differentiation (CD8+) T cell response in spite of exogenous administration, it
circumvents the need for identification of T-cell epitopes of individual cancers, and it
minimizes the possibility of generating epitope variants. Furthermore, heat shock
protein-peptide complexes have elicited tumor rejection and CD8+ T cell response without
adjuvant therapies. Heat shock protein-peptide complexes, such as HSPPC-96, can be isolated
from human tumors, and when injected back into the patient from whom they were isolated, may
present a unique opportunity to deliver a vaccine specific to that patient.

Inclusion Criteria:

- Arm A: Newly Diagnosed High Grade Glioma Tumor

- Arm B: Recurrent, resectable High Grade Glioma or Ependymoma

- Stable Neurologic Status

- Lanksy/Karnofsky score greater than or equal to 50.

- Adequate Bone Marrow Function (ANC≥ 1000/μL, platelets≥ 100,000/μL transfusion
independent, Hemoglobin ≥ 8.0 gm/dL with or without transfusion support)

- Adequate Liver Function (Bilirubin ≤ 2x institutional normal for age, Alanine
transaminase (ALT) ≤ 5x institutional normal for age, Aspartate Aminotransferase (AST)
≤ 5x institutional normal for age)

- Adequate Renal Function (Normal creatinine for age and/or glomerular filtration rate ≥
70 mls/min/1.73 m2)

- Female patients of childbearing potential must have a negative serum or urine
pregnancy test

Exclusion Criteria:

- Patients with unresectable disease are not eligible.

- Patients with primary spinal cord tumors are not eligible.

- Patients with metastatic disease are not eligible for Arm A (this does NOT apply to
Arm B).

- Patients with a known allergy to any component of the vaccine or any compounds of
similar chemical or biologic composition of the vaccine are not eligible.

- Patients with known auto-immune disease are excluded.

- Patients with known immunodeficiency are excluded.

- Patients with a concurrent malignancy are excluded.

- Clinically Significant Concurrent Illness

- Patients receiving any other anticancer or investigational drug

- Patients with uncontrolled seizure disorders

- Patients whose central nervous system (CNS) tumor is considered a secondary malignancy
from prior therapies