Transformation of Plexiform Neurofibromas to Malignant Peripheral Nerve Sheath Tumors in Neurofibromatosis Type 1

Background:

- NF1 is an autosomal dominant genetic disorder characterized by distinct features
including the development of benign plexiform neurofibromas (PN) and malignant
peripheral nerve sheath tumors (MPNST) tumors of the nervous system.

- Development of MPNST typically results from malignant transformation in a preexisting
PN. Associated symptoms may overlap and be difficult to distinguish from growth of a
benign PN. Currently surgery is the only standard treatment for PN and MPNST.

- The 5-year overall survival rate for NF1 patients with a MPNST is poor; therefore, early
detection of malignant transformation of a PN is an important goal.

- Fluoro-deoxy-glucose (FDG) positron emission tomography (PET) in NF1 has utility in
detecting malignant transformation. However, concerning lesions can have high FDG uptake
and be benign on biopsy.

- Fluoro-thymidine (FLT) PET measures cell cycling and proliferation. Malignant lesions
have higher proliferation rates than benign tumors; therefore, FLT-PET may be sensitive
and specific in the early detection of malignant transformation and assess response.

- Genetic analysis is an important component in evaluating the transformation of PN to
MPNST. Biallelic NF1 and tumor suppressor gene mutations (p53, INK4A, p27kip1),
increased Ras activity and abnormal growth factor signaling have been described, but
there is no known signature for MPNST.

- Massively parallel ( next generation ) sequencing technology permits whole-genome,
whole-exome and transcriptome sequencing of multiple tumors including MPNST.

Objectives:

- Determine the feasibility of FLT PET in patients with NF1 and MPNST or lesions
concerning for MPNST, or MPNST.

- Evaluate the ability of FLT PET to distinguish benign PN from malignant lesions, and to
determine if FLT PET is more accurate than FDG PET in correctly classifying a tumor as
benign or malignant.

- Evaluate the feasibility of whole-exome sequencing and other genetic/genomic methods,
including detection of epigenetic and/or expression changes and RNA Seq of tumor (MPNST
or lesion concerning for MPNST and adjacent benign PN) biopsies using interventional
radiology sampling techniques in consenting individuals with NF1 participating in
10-C-0086.

- Perform detailed clinical analysis of individuals with NF1 and MPNST or lesions
concerning for MPNST.

- Perform detailed pathologic analysis of biopsy specimens from tumor areas to determine
if increased uptake of FDG or FLT predicts for malignant transformation.

- Identify somatic genetic variants that distinguish PN from MPNST and from germline
sequence by whole-exome sequencing potentially identifying targets for treatment.

Eligibility:

- NF1 patients with lesions concerning for malignancy or with active MPNST.

- Willingness to enroll on NCI protocol 08-C-0079: Natural History Study and Longitudinal
Assessment of Children, Adolescents, and Adults with Neurofibromatosis Type 1.

Design:

- Up to 15 patients will be enrolled on this pilot study.

- Patients will undergo the following evaluations:

- Detailed clinical evaluation of NF1 manifestations on NCI protocol #08-C-0079

- Imaging studies including:

- MRI, FDG-PET/CT scans (as standard care) in all subjects; and

- [(18)F]-FLT-PET/CT (research study) in subjects 10 years of age or older

- Genetic counseling (if participating in the germline blood sampling and biopsy analysis
portion of the study)

- Tissue analysis:

---Patients 18 years of age or older with MPNST will participate in tissue analysis, if
consenting and appropriately preserved archival tissue is available, or if patient
agrees to optional research biopsy (if consented and safe). Patients with lesions
concerning for malignancy will undergo clinically indicated biopsies of concerning
lesions and of adjacent benign PN (if consented and safe) for detailed pathologic
analysis and whole-exome sequencing (co-enrollment on 10-C-0086 Comprehensive Omics
Analysis of Pediatric Solid Tumors and Establishment of a Repository for Related
Biological Studies). Biopsies to be directed by PET fusion imaging in interventional
radiology.

- Whole-exome sequencing of a germline blood sample (optional) if participating in the
tissue analysis (co-enrollment on 10-C-0086 Comprehensive Omics Analysis of Pediatric
Solid Tumors and Establishment of a Repository for Related Biological Studies).

- To better characterize lesions concerning for MPNST and predict those at higher risk for
malignant transformation, we will correlate clinical and imaging findings, including
radiographic evaluation with FDG-PET/CT, and [(18)F]-FLT-PET/CT, pathologic evaluation
of tumor biopsies (if available), and analysis of whole exome sequencing of germline
blood samples (if consented) and of tumor samples (when available).

- INCLUSION CRITERIA:

1. Age:

- No upper age limit for patient enrollment.

- FLT PET: will only be performed in patients greater than or equal to 10 years old

- Research biopsies in consenting patients with MPNST: will only be performed in
patients greater than or equal to 18 years old

2. Diagnosis:

- Patients who are diagnosed with NF1 using the NIH Consensus Conference criteria or
have a confirmed NF1 mutation with analysis performed in a CLIA certified laboratory.
NF1 mutation testing to confirm eligibility will not be performed on this protocol,
but as part the POB separate screening study.

- For the clinical diagnosis of NF1 all study subjects must have at two or more
diagnostic criteria for NF1 listed below (NIH Consensus Conference):

1. Six or more caf(SqrRoot)(Copyright)-au-lait spots (greater than or equal to 0.5
cm in prepubertal subjects or greater than or equal to 1.5 cm in postpubertal
subjects)

2. Greater than or equal to 2 neurofibromas or 1 plexiform neurofibroma

3. Freckling in the axilla or groin

4. Optic glioma

5. Two or more Lisch nodules

6. A distinctive bony lesion (dysplasia of the sphenoid bone or dysplasia or
thinning of long bone cortex)

7. A first-degree relative with NF1

3. NFI tumor manifestations

Subjects must have:

1. Diagnosis of NF1 with a lesion concerning for MPNST

-Criteria include pain, growth of a known plexiform neurofibroma, abnormality on
functional imaging study (FDG-PET) or change in clinical exam.

OR

2. Diagnosis of NF1 with a histologically confirmed MPNST.

4. Subjects must be eligible for and willing to participate and sign consent for NCI
protocol 08-C-0079: Natural History Study and Longitudinal Assessment of Children,
Adolescents, and Adults with Neurofibromatosis Type 1, for the clinical evaluation
necessary for this study.

5. Prior and current therapy:

For NF1 related benign tumor manifestations there is no standard effective medical
treatment, and surgery is the only standard treatment. Chemotherapy and radiation therapy
are additional treatment options for malignant NF1 related tumors. For the purpose of this
study subjects who have not previously received medical or surgical treatment, patients who
have previously received medical or surgical treatment, and subjects who are currently
receiving medical treatment and or radiation for a NF1 related manifestation will be
eligible.

Patients must be recovered from acute toxicities of prior therapy in order to be able to
safely undergo biopsies proposed on the trial. Prior and current treatment for NF1 related
manifestations will be recorded on protocol 08-C-0079.

Prior radiation therapy and chemotherapy in patients with MPNST must not have been
administered within 4 weeks prior to enrollment.

6. Performance Status:

ECOG less than or equal to 3. Subjects who are wheelchair bound because of paralysis will
be considered ambulatory when they are up in their wheelchair. Subjects have to be able to
travel to the NIH for evaluations.

7. Informed Consent:

All patients or their legal guardians (if the patients is<18 years old) must sign an
IRB-approved document of informed consent to demonstrate their understanding of the
investigational nature and the risks of this study before any protocol-related studies are
performed. When appropriate, pediatric subjects will be included in all discussions.

8. Hematologic criteria (applicable only in patients undergoing biopsy)

- Platelet count has to be greater than or equal to 100,000/microL

- Patients should have INR<1.4 and PT less than or greater to 40 seconds (unless due to
lupus anticoagulant). In patients not meeting these parameters, clearance by
hematology will be required prior to undergoing biopsy.

EXCLUSION CRITERIA:

1. Allergy or relative contraindications to MRI contrast agents.

2. Patients who require sedation for imaging studies will be excluded from the FLT PET
scan research test. They will undergo only the standard of care MRI and FDG PET scan.

3. Contraindication to MRI scanning, such as surgery that involves metal clips or wires
or metal prostheses which might be expected to cause tissue damage or produce image
artifacts.

4. Patients with severe chronic renal insufficiency (glomerular filtration rate < 30
mL/min/1.73 m(2)), hepatorenal syndrome or post-liver transplantation.

5. History of prior fluorothymidine allergy or intolerance.

6. Participants with severe claustrophobia not relieved by oral anxiolytic medication or
patients weighing >136 kg (weight limit for scanner table)

7. Pregnant women are excluded from this study because of the effects of radioactive
materials with the potential for teratogenic or abortifacient effects. Because there
is an unknown but potential risk for adverse events in nursing infants secondary to
treatment of the mother with radioactive materials, breastfeeding should be
discontinued.

8. Requirement for medications, which interfere with platelet function, such as aspirin,
which cannot be stopped within 1 week prior to the biopsy (applicable only to patients
undergoing biopsy).