TAT-10: Reduction of Radiation Exposure to the Large Intestine During Ra223 Alpha Therapy with Oral Administration of Barium Sulfate

Kanazawa, Japan (UroToday.com) Ra223 alpha therapy has been shown to be effective in treating bone metastases of metastatic castration-resistant prostate cancer patients. However, some patients have shown gastrointestinal side effects such as nausea and diarrhea. In this mouse study, we investigate whether these side effects may be reduced by oral administration of barium sulfate (BaSO4), a co-precipitating agent of Ra. 

The treatment protocol consisted of oral administration of BaSO4 (150 mg) followed one hour later by Ra223 (10 kBq). The biodistribution was determined at 1,2,4,6, and 24 hours after injection. Organs examined included liver, kidney, small intestine, large intestine, spleen, femur and blood. Urine and feces were also collected.

BaSO4 significantly (P < 0.05) reduced Ra223 accumulation in the large intestine at 1,2, and 4 hours after injection compared to the control group without BaSO4. On the other hand, Ra223 was slightly increased in urine and feces 24 hours after injection. Encouraged by this positive effect, we also investigated whether a laxative (0.3 ml of 50% glycerin administered rectally 4 hours after Ra223 injection) would show similar effects. The laxative reduced Ra223 in the large intestine to a level similar to of BaSO4. The combination of both BaSO4 and laxative treatment showed no additional benefit to the large intestine over either one alone.

Presented By: Sayaka Hanadate from Toho University and National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan

Written By: William Carithers, Lawrence Berkeley National Laboratory

at the 10th International Symposium on Targeted Alpha Therapy (TAT-10)  May 31 - June 1, 2017 - Kanazawa, Japan.