Combination of External Beam Radiotherapy With 153Sm-EDTMP to Treat High Risk Osteosarcoma

DAY 1 Tracer dose 153Sm-EDTMP administration (1 mCi/kg) SPECT/High-resolution CT at 4 hours.
SPECT/CT (low resolution) at 24 and 48 hrs

DAY 7 Individualized treatment dose 153Sm-EDTMP administration (max 30 mCi/kg) SPECT scans at
4, 24 and 48 hours

DAY 21 (2 weeks following treatment dose administration) Auto-Stem cell infusion

DAY 40 (approximately two weeks after stem cell rescue) Initiate external beam radiation
therapy upon count recovery

One month following completion of all therapy Response assessment with repeat imaging
(CT/MRI, Tc-99m bone scan) 18F-MISO/FDG PET

Inclusion Criteria:

- Patients must be between 13 and 65 years of age, inclusive

- Must have unresectable primary tumor or metastases

- Must have measurable disease that is demonstrated by positive Tc-99m Bone Scan. Not
all lesions must be positive on bone scan.

- Creatinine clearance >70ml/min/1.73m2

- ANC >500/mm3

- Platelets >50,000/mm3

- Life expectancy > 8 weeks

- Karnofsky performance status >50%

- Stem cell product collected prior to the infusion of Samarium must be available,
either by peripheral stem cell mobilization or bone marrow harvest prior to trial
entry.

Exclusion Criteria:

- Patient may not be pregnant or breastfeeding.

- Patients who have received prior radiotherapy to all areas of current active disease
are not eligible.