RADIATION-ABSORBED DOSE ESTIMATES TO NORMAL ORGANS FOLLOWING INTRAPERITONEAL RE-186-LABELED MONOCLONAL-ANTIBODY - METHODS AND RESULTS

The radiation-absorbed dose was estimated following i,p, administratio n of a Re-186-labeled murine antibody, NR-LU-10, in 27 patients with a dvanced ovarian cancer. Data for the dosimetry estimation were obtaine d from quantitative gamma camera imaging and gamma counting of serum a nd i,p, fluid radioactivity. A peritoneal cavity model was used to est imate the dose to normal organs from radioactivity within the peritone al cavity, Estimates of radiation-absorbed dose to normal organs in ra d/mCi administered (mean + SD) were: whole body, 0.7 + 0.3; marrow, 0. 4 + 0.1; liver, 1.9 + 0.9; kidneys, 0.2 + 0.2, and intestine, 0.2 + 0. 2, The radiation-absorbed dose estimates to the normal peritoneal surf ace varied depending on the volume of fluid infused and whether the ac tivity was measured by the gamma camera or from the peritoneal fluid s amples, Using gamma camera data, the peritoneal surface dose ranged fr om 7 to 36 rads/mCi; when using the peritoneal fluid sample data, the dose ranged from 2 to 25 rads/mCi, Myelosuppression, observed in sever al patients, correlated best with marrow dose estimates based on the s erum radioactivity, and significant toxicity was observed at marrow do ses greater than 100 rads. The noninvasive methods of dose estimation for i,p. administration of radioimmunoconjugates provided reasonable a bsorbed dose estimates when compared with previously described, more i nvasive methods.