18F-FLT Positron Emission Tomography and Diffusion-Weighted Magnetic Resonance Imaging in Planning Surgery and Radiation Therapy and Measuring Response in Patients With Newly Diagnosed Ewing Sarcoma

PRIMARY OBJECTIVES:

I. Establish correlation between 18F-FLT positron emission tomography (PET) activity,
apparent diffusion coefficients (ADC) values from diffusion-weighted magnetic resonance
imaging (DW-MRI), fludeoxyglucose F 18 (18F-FDG) PET activity, magnetic resonance imaging
(MRI) contrast enhancement, and pathologic response for Ewing sarcoma.

II. Assess the efficacy of detecting therapy induced changes in 18F-FLT PET uptake and ADC
from DW-MRI for more accurately predicting local control, event-free survival, and overall
survival as compared to standard prognostic factors (e.g. change in tumor size).

III. Compare radiotherapy target volume delineation with pre- and post-chemotherapy 18F-FLT
PET and DW-MRI information to delineation with pre-chemotherapy conventional MRI to determine
role of advanced imaging in radiotherapy treatment planning for Ewing sarcoma.

SECONDARY OBJECTIVES:

I. Establish correlation between 18F-FLT PET activity, ADC values from DW-MRI, 18F-FDG PET
activity, MRI contrast enhancement, and biomolecular assays for Ewing sarcoma.

II. Determine imaging thresholds to discriminate between viable and necrotic tumor, as
established through pathologic correlations.

III. Assess efficacy of advanced imaging for more accurately guiding biopsy targeting by
comparing planned targeting with standard (MRI contrast enhancement) vs. advanced imaging
(18F -FLT PET and DW-MRI).

IV. Compare post-treatment response assessment with 18F-FLT PET and DW-MRI vs. 18F-FDG PET to
determine whether 18F-FLT PET and ADC information is more accurate than 18F-FDG PET for
distinguishing between necrosis and non-specific inflammation immediately following
treatment.

V. Estimate potential reduction in acute and late side effects based on modified radiation
therapy (RT) treatment volumes with pre- and post-chemotherapy 18F-FLT PET and DW-MRI
information as compared to volumes delineated with pre-chemotherapy conventional MRI.

VI. Evaluate automatic image segmentation techniques for 18F-FLT PET and DW-MRI, comparing
against biopsy determined imaging thresholds and expert Nuclear Medicine and MR Radiologist
contours.

OUTLINE:

Patients undergo 18F-FLT PET, 18F-FDG PET, and DW-MRI the week prior to induction therapy,
within one week after the completion of induction therapy, the week prior to RT (for patients
that received surgery), and within 1 week of completion of RT.

After completion of study intervention, patients are followed up every 3 months for 1 year
and then every 6 months for up to 4 years.

Inclusion Criteria:

- Histological confirmation of newly diagnosed localized or newly diagnosed with
metastatic Ewing sarcoma (ES) or primitive neuroectodermal tumor (PNET) of bone or
soft tissue

- Planning to receive definitive RT or surgery with or without adjuvant RT

- Willing to sign release of information for any follow-up records

- Provide informed written consent if >= 18 years; if < 18 years, provide informed
written assent and parent or legal guardian provide informed written consent

- Patients must have measurable disease

- Willingness to participate in mandatory imaging studies

- Willingness to provide mandatory pathology samples for correlative research

Exclusion Criteria:

- Unable to undergo MRI scans with contrast (e.g. cardiac pacemaker, defibrillator,
kidney failure)

- Unable to undergo 18F-FLT PET scan

- Any of the following:

- Pregnant women

- Nursing women

- Men or women of childbearing potential who are unwilling to employ adequate
contraception