Preoperative characterisation of clear-cell renal carcinoma using iodine-124-labelled antibody chimeric G250 (124I-cG250) and PET in patients with renal masses: a phase I trial.
BACKGROUND
Preoperative identification of tumour type could have important implications for the choice of treatment for renal cancers. Antibody cG250 reacts against carbonic anhydrase-IX, which is over-expressed in clear-cell renal carcinomas. We aimed to assess whether iodine-124-labelled antibody chimeric G250 ((124)I-cG250) PET predicts clear-cell renal carcinoma, the most common and aggressive renal tumour.


METHODS
26 patients with renal masses who were scheduled to undergo surgical resection by laparotomy received a single intravenous infusion of 185 MBq/10 mg of (124)I-cG250 over 20 min in this open-label pilot study. Surgery was scheduled 1 week after (124)I-cG250 infusion. PET and CT scanning of the abdomen, including the kidneys, within 3 h before surgery was planned for all patients. The obtained images were graded as positive (defined as a tumour-to-healthy-kidney ratio >3 to 1) or negative for antibody uptake, and the surgeon was informed of the scan results before surgery. After surgery, resected tumours were histopathologically classified as clear-cell renal carcinoma or otherwise. The trial is registered on the clinical trials site of the National Cancer Institute website http://clinicaltrials.gov/ct/show/NCT00199888.


RESULTS
One patient received inactive antibody and was excluded from analysis. 15 of 16 clear-cell carcinomas were identified accurately by antibody PET, and all nine non-clear-cell renal masses were negative for the tracer. The sensitivity of (124)I-cG250 PET for clear-cell kidney carcinoma in this trial was 94% (95% CI 70-100%); the negative predictive value was 90% (55-100%), and specificity and positive predictive accuracy were both 100% (66-100% and 78-100%, respectively).


CONCLUSIONS
PET with (124)I-cG250 can identify accurately clear-cell renal carcinoma; a negative scan is highly predictive of a less aggressive phenotype. Stratification of patients with renal masses by (124)I-cG250 PET can identify aggressive tumours and help decide treatment.
Divgi
Chaitanya R
CR
Memorial Sloan-Kettering Cancer Center, New York, NY, USA. chaitanya.divgi@uphs.upenn.edu
Pandit-Taskar
Neeta
N
Jungbluth
Achim A
AA
Reuter
Victor E
VE
Gönen
Mithat
M
Ruan
Shutian
S
Pierre
Christine
C
Nagel
Andrew
A
Pryma
Daniel A
DA
Humm
John
J
Larson
Steven M
SM
Old
Lloyd J
LJ
Russo
Paul
P
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007457:Iodine Radioisotopes; D007668:Kidney / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D011300:Preoperative Care; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; C106533:G250 monoclonal antibody; D007457:Iodine Radioisotopes