Abstract
1747
Objectives Primary and metastatic bone cancer are significant sources of morbidity and mortality in cancer patients. Available treatments include bisphosphonates, anti-inflammatory and opioid pain medication, and radiation therapy. Targeted radioisotopes deliver radiation directly to affected tissue while sparing surrounding normal tissue. Samarium-153-DOTMP consists of samarium-153 which is an excellent radioisotope for imaging and treatment, and DOTMP which is a superior chelator relative to other available constructs. Our objective was to confirm localization of the chelate to known sites of bone tumors in dogs, and to identify myelosuppression or other toxicity.
Methods Dogs with spontaneously-occurring bone cancer (4 primary appendicular osteosarcoma and 2 metastatic carcinoma) were recruited from the hospital population at the University of Missouri Veterinary Medical Teaching Hospital. Each dog was evaluated with blood count, biochemical profile, urinalysis, and technetium-99m-MDP skeletal scintigraphy. All dogs were treated with 1 mCi/kg samarium-153-DOTMP intravenously and monitored using weekly blood counts and quality-of-life assessments (including lameness). Gamma scintigraphy was acquired at 20-24 hours post injection.
Results Treatment was well tolerated. There was excellent correlation between pretreatment technetium and post-treatment samarium-153-DOTMP scintigraphy. Region of interest ratios of uptake between tumor and contralateral normal bone ranged from 12.6-45.7 and ratio of tumor to adjacent bone ranged from 8.6-24.8. Two dogs experienced transient peritumoral swelling after injection. No dog experienced a dose-limiting hematologic toxicity.
Conclusions Given the favorable toxicity profile, higher doses should be explored to maximize the therapeutic ratio for samarium-153-DOTMP, a novel skeletal targeted radiotherapeutic agent.
Research Support NCI R43CA15060