Patient-specific dosimetry of indium-111- and yttrium-90-labeled monoclonal antibody CC49.
The objective of this work was to develop patient-specific dosimetry for patients with metastatic gastrointestinal tract cancers who received 111In-CC49 IgG for imaging before therapy with 90Y-CC49 IgG.


METHODS
Whole-body imaging of 12 patients, who received 111-185 MBq (3-5 mCi) of 111In-CC49, commenced in < 2 hr postinfusion and was continued daily for 4-5 days. SPECT data were acquired at 24 and 72 hr to determine the range of 111In-CC49 activity concentrations in tumors and normal organs. Time-activity curves were generated from the image data and scaled from 111In-CC49 to 90Y-CC49 for dosimetric purposes. Absorbed-dose calculations for 90Y-CC49 included the mean and range in tumor and normal organs. Computed 90Y-CC49 activity concentrations were compared with measurements on 10 needle biopsies of normal liver and four tumor biopsies.


RESULTS
In 9 of 10 normal liver samples, the range of computed 90Y-CC49 activity concentrations bracketed measured values. This was also the case for 3 of 4 tumor biopsies. Absorbed-dose calculations for 90Y-CC49 were based on patients' images and activities in tissue samples and, hence, were patient-specific.


CONCLUSIONS
For the radiolabeled antibody preparations used in this study, quantitative imaging of 111In-CC49 provided the data required for 90Y-CC49 dosimetry. The range of activities in patients' SPECT images was determined for a meaningful comparison of measured and computed values. Knowledge of activity distributions in tumors and normal organs was essential for computing mean values and ranges of absorbed dose and provided a more complete description of the absorbed dose from 90Y-CC49 than was possible with planar methods.
Leichner
P K
PK
Department of Radiology, University of Nebraska Medical Center, Omaha 68198-1050, USA.
Akabani
G
G
Colcher
D
D
Harrison
K A
KA
Hawkins
W G
WG
Eckblade
M
M
Baranowska-Kortylewicz
J
J
Augustine
S C
SC
Wisecarver
J
J
Tempero
M A
MA
D000042:Absorption; D000368:Aged; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000276:immunology; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary; D006023:Glycoproteins / Q000276:immunology; D006207:Half-Life; D006801:Humans; D007205:Indium Radioisotopes / Q000493:pharmacokinetics; D008099:Liver / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D016499:Radioimmunotherapy; D011879:Radiotherapy Dosage; D013154:Spleen / Q000528:radiation effects; D015899:Tomography, Emission-Computed, Single-Photon; D015021:Yttrium Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use*
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D006023:Glycoproteins; D007205:Indium Radioisotopes; D015021:Yttrium Radioisotopes; C047052:tumor-associated antigen 72