Immunoscintigraphy: Importance for researchers and patients

Preliminary Study on Radioimmunodiagnosis of Experimental Tumor Models Using Technetium-99m-Labeled Anti-C-erbB-2 Monoclonal Antibody

Aims and background

One of the great challenges of oncology is to improve methods for early tumor detection. Diagnosis of premalignant lesions and early stage primary tumors is crucial for the success of cancer therapy and increased survival rates. Growth factor receptors localized to the cell membrane play a vital role in cancer. Monoclonal antibodies labeled with radioisotopes have been used extensively for radioimmunodiagnosis and radioimmunotherapy of various malignancies. A preliminary study on immunoscintigraphy was carried out on animal tumor models using 99mTc-labeled monoclonal antibody CIBCgp185 generated against the C-erbB-2 oncoprotein with a view to develop technologies for in vivo radioimmunodetection and localization of human breast cancer.

Methods

Mammary tumor xenografts induced using BT474 cells, a breast carcinoma cell line showing overexpression of C-erbB-2, were used for immunoscintigraphic studies.

Results

Scintigrams showed high radiolabel uptake by the tumor tissue of the mice belonging to the experimental group, whereas in control animals no radiolabel uptake was visualized. Biodistribution studies correlated well with scintiscans.

Conclusions

The results indicate the potential application of this monoclonal antibody for in vivo diagnosis of occult malignancies of tumors with overexpression of C-erbB-2.

Radioimmunoscintigraphy in patients with ovarian cancer

The use of radiolabeled monoclonal antibodies (MoAbs) has significantly improved the ability to detect tumor antigens, thus improving in vivo tumor diagnosis and treatment. The management of ovarian carcinoma still poses a challenging medical problem. Clinical trials using radioimmunoscintigraphy or a hand-held gamma detection probe intraoperatively were performed in patients with clinical evidence of primary or recurrent ovarian cancer. Immunoscintigraphy of ovarian cancer lesions has been performed mainly with 99mTc, 111In and 123I labeled with HMFG1, HMFG2, OC-125, B72.3, H17E2, OVTL3, MoAb170, Mov18 and other MoAbs. Antibody guided imaging using radioimmunoscintigraphy has demonstrated improved targeting of ovarian cancer, resulting in a highly sensitive and specific method. However, it is not yet known which type of MoAb is the most efficient for radioimmunoscintigraphy. Since these tumors represent a potentially curable disease, radioimmunoscintigraphy could contribute mainly to accurate staging as a supplementary to conventional diagnostic methods, as well as for the localization of active disease after chemotherapy and monitoring for the presence of recurrent disease. Nevertheless, prospective studies in a large number of patients should be undertaken in order to further evaluate the diagnostic contribution of this approach.