Diagnostic efficacy and safety of 99mtc-labeled monoclonal antibody ior c5 in patients with colorectal and anal carcinomas: final report clinical trial phase I/II.

Unlabelled: Monoclonal antibody (mAb) ior c5 is an IgG1, which recognizes a glycoprotein tumor specific antigen IOR C2 over expressed in the surface of colon and ovarian cancer cells. The aim of the present work was to evaluate the diagnostic efficacy of the 99mTc-labeled mAb ior c5 for the detection of colorectal tumors, its metastases and recurrences.

Methods: Eighty six patients with colorectal or anal cancer, mean age 57 +/- 13 yrs, were involved in a phase 1/11 multicentric, open clinical trial to assess the ability of Radioimmunoscintigraphy (RIS) with 99mTc- mAb ior c5 to detect those tumors. Seventy-four patients received 1 mg of c5 labeled with 1480-1850 MBq to determinate diagnosis efficacy and safety of murine mAb by intravenously (i.v.) bolus injection (group 1). In order to evaluate pharmacokinetic, bio distribution and dosimetry of this radiolabel molecule, 12 patients received 3 mg of labeled ior c5. Planar anterior and posterior images of the lesion sites and suspected metastases were acquired at 2, 4 and 18-24 hours after injection using a matrix size 128 x128 and 500 Kcounts per view. SPECT were scanned at 5 hr post-injection, using a 360' circular orbit with 64 images. HAMA response was measured in serum at 2, 4, 8 and 12 week post-administration.

Results: Labeling efficiency was (97.8 - 0.6) %. No adverse reactions or side effects were observed. Overall sensitivity, specificity, accuracy, positive and negative predictive values of the immunoscintigraphy were 95.80%, 100%, 96.51%, 100.0% and 82.35%, respectively. Unknown metastases were detected in 37 of 86 cases (43.02%). No HAMA response was found.

Conclusions: Immunoscintigraphy with 99mTc-labeled mAb ior c5 could be a useful procedure for the diagnosis and follow-up of the patients with colorectal tumors, its metastasis and recurrences.