Gemcitabine radiosensitization after high-dose samarium for osteoblastic osteosarcoma

Area of Science:

• Oncology
• Nuclear Medicine
• Radiopharmaceutical Therapy

Background:

• Osteoblastic metastases and osteosarcoma can concentrate bone-seeking radiopharmaceuticals.
• High-dose samarium ethylenediaminetetramethylenephosphonate (153Sm-EDTMP) is used for osteosarcomas.
• Gemcitabine is a radiosensitizer with potential to enhance radiopharmaceutical effectiveness.

Purpose of the Study:

• To evaluate the effectiveness of combining high-dose 153Sm-EDTMP with gemcitabine in patients with osteoblastic lesions.
• To assess the safety and toxicity profile of this combination therapy.

Main Methods:

• Fourteen patients with osteoblastic lesions received 30 mCi/kg 153Sm-EDTMP.
• Gemcitabine was administered one day after samarium infusion.
• Autologous stem cell reinfusion was performed to manage hematopoietic toxicity.

Main Results:

• A single dose of gemcitabine (1,500 mg/m2) with 153Sm-EDTMP showed minimal toxicity (pancytopenia).
• Daily gemcitabine regimens resulted in excessive toxicity (grade 3 mucositis) in one of two patients.
• Six partial remissions and two mixed responses were observed at 6-8 weeks, with no durable responses at >1 year follow-up.

Conclusions:

• High-dose 153Sm-EDTMP plus gemcitabine demonstrates moderate palliative activity for osteosarcoma with osteoblastic lesions.
• Additional local and systemic control measures are necessary for durable control of relapsed osteosarcoma.
• The strategy of combining radiopharmaceuticals with radiosensitizers may offer synergistic benefits.