Biodistribution of 111In-labelled engineered human antibody CTM01 (hCTM01) in ovarian cancer patients: influence of prior administration of unlabelled hCTM01.
mAb hCTM01 binds a carcinoma-associated antigen, the MUC1 gene product. The antigen is also present in the circulation, and administration of 111In-labelled hCTM01 results in the formation of immune complexes with enhanced accumulation in the liver. To avoid the unwanted effect of circulating radioactive immune complexes, a strategy to remove the circulating antigen was investigated using a split-dosage schedule. Eleven patients suspected of having ovarian carcinoma were injected with 1 mg/kg unlabelled hCTM01, 1 h before receiving 0.1 mg/kg 111In-labelled hCTM01 (100 M Bq). The amount of radioactivity was determined in resected tumour tissue, various normal tissues and blood samples obtained at laparotomy 6 days postinjection (p.i.). In all patients, the circulating antigen decreased to its nadir after the unlabelled antibody infusion and immune complex formation was demonstrated. Uptake in tumour deposits 6 days p.i. was 11.1 times higher than in normal tissues (P < 0.0001) and 5.9 times higher than in blood (P < 0.0001). 111In activity in liver tissue was comparable to 111In uptake in tumour tissue, and considerably lower than previously reported in patients not pretreated with unlabelled antibody. The split-dosing strategy would appear to be advantageous for use of hCTM01 as a specific carrier for the delivery of cytotoxic agents to patients with ovarian cancer.
Department of Obstetrics and Gynaecology, University Hospital Vrije Universiteit, Amsterdam, The Netherlands.
H M
HM
Prinssen
C F
CF
Molthoff
R H
RH
Verheijen
T J
TJ
Broadhead
P
P
Kenemans
J C
JC
Roos
Q
Q
Davies
A C
AC
van Hof
M
M
Frier
W
W
den Hollander
A J
AJ
Wilhelm
T S
TS
Baker
M
M
Sopwith
E M
EM
Symonds
A C
AC
Perkins
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007205:Indium Radioisotopes; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000378:metabolism*; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D007205:Indium Radioisotopes