Brain Stem Gliomas Treated With Adoptive Cellular Therapy During Focal Radiotherapy Recovery Alone or With Dose-intensified Temozolomide (Phase I)

The standard of care for children with DIPG includes external beam focal radiotherapy (RT)
but outcomes have remained dismal despite this treatment. The addition of oral Temozolomide
(TMZ) concurrently with focal irradiation followed by maintenance monthly TMZ was also found
to be safe but ineffective. However, in the context of an immunotherapy strategy, it might be
beneficial to use TMZ as an adjuvant therapy during and following radiotherapy. Recent
pre-clinical and clinical studies in adults with have shown that both myeloablative (MA) and
non-myeloablative (NMA) chemotherapy induce a profound but transient lymphopenia and,
somewhat counterintuitively, vaccination during recovery from this lymphopenic state and/or
the adoptive transfer of tumor-specific lymphocytes into lymphodepleted hosts leads to
dramatic in vivo T cell expansion and potent immunologic and clinical responses. Therefore,
the study team expects that tumor-specific lymphocytes, expanded ex vivo with the use of
TTRNA-pulsed DCs may provide a source of lymphocytes that preferentially expand in this
lymphopenic environment following TMZ, and serve as a source of responder cells to subsequent
DC vaccination.

Although TMZ does induce profound lymphopenia in children with central nervous system (CNS)
tumors, it has not been conclusively shown to help in augmenting vaccine-induced immune
responses in this population. Therefore, patients in this study would either receive
concurrent TMZ during RT and immunotherapy during and after maintenance cycles of
dose-intensive TMZ (Group A) or focal radiotherapy alone and immunotherapy without
maintenance DI TMZ (Group B). Immune responses during cycles of DC vaccination with or
without DI TMZ will be evaluated in both treatment groups. The immunotherapy regimen will
consist of TTRNA-DC vaccines alone followed by adoptive cellular therapy consisting of ex
vivo expanded tumor-reactive lymphocytes coupled with TTRNA-DC vaccines and autologous HSCs.

Patients in Group B will not receive DI TMZ, however, they will receive lymphodepletion with
cyclophosphamide + fludarabine after DC vaccination and prior to the intravenous infusion of
ex vivo expanded tumor-reactive lymphocytes, as T cell engraftment and persistence has been
shown to be augmented by lymphodepletion in numerous studies. TTRNA-pulsed DCs will be given
in conjunction with the adjuvants GM-CSF and tetanus-diphtheria toxoid (Td) vaccine which the
study team have shown can significantly enhance clinical responses to DC vaccination.

Inclusion Criteria:

Initial Screening

- Radiologically confirmed DIPG and patient and/or parents/guardian willing to consent
to biopsy;

- Karnofsky Performance Status (KPS) of > 50% (KPS for > 16 years of age) or Lansky
performance Score (LPS) of ≥ 50 (LPS for ≤ 16 years of age) assessed within 2 weeks
prior to registration;

- Bone Marrow;

- ANC (absolute neutrophil count) ≥ 1000/µl (unsupported)

- Platelets ≥ 100,000/µl (unsupported)

- Hemoglobin > 8 g/dL (can be transfused)

- Renal;

- Serum creatinine ≤ upper limit of institutional normal

- Hepatic;

- Bilirubin ≤ 1.5 times upper limit of institutional normal for age

- SGPT (ALT) ≤ 3 times upper limit of institutional normal for age

- SGOT (AST) ≤ 3 times upper limit of institutional normal for age

- Patients of childbearing or child-fathering potential must be willing to use medically
acceptable forms of birth control while being treated on this study.

Post Biopsy

- Patients with post-surgical neurological deficits should have deficits that are stable
for a minimum of 1 week prior to registration;

- Pathologic diagnosis of glioma on tumor biopsy.

Exclusion Criteria:

- Patients with severe dysphagia, obtundation, or tetraplegia (poor risks for anesthesia
and biopsy procedure);

- Absence of tumor on biopsy specimen;

- Pregnant or need to breast feed during the study period (Negative serum pregnancy test
required)

- Known autoimmune or immunosuppressive disease or human immunodeficiency virus
infection;

- Patients with significant renal, cardiac, pulmonary, hepatic or other organ
dysfunction;

- Severe or unstable concurrent medical conditions;

- Patients who require corticosteroids above physiologic doses (>4 mg/day dexamethasone)
after chemoradiotherapy;

- Patients scheduled to receive any other concurrent anticancer or investigational drug
therapy;

- Prior allergic reaction to TMZ, GM-CSF, or Td;

- Patients who are unwilling or unable to receive treatment and undergo follow-up
evaluations at University of Florida;

- Patient and/or parent/guardian demonstrating an inability to comply with the study
and/or follow-up procedures.