In-111 CYT-103 immunoscintigraphy in the imaging of ovarian carcinoma

Quantitative analysis of In-111 satumomab pendetide immunoscintigraphy. An aid to visual interpretation of images in patients with suspected carcinomatosis

The diagnosis of the diffuse intrapertioneal spread of ovarian or colorectal carcinoma (carcinomatosis) can be difficult when based on visual interpretation of immunoscintigraphic images alone. Twenty-nine patients with either colorectal or ovarian cancer were retrospectively evaluated by three technologists for carcinomatosis employing a quantitative analysis technique that compares uptake of In-111 satumomab pendetide (Oncoscint CR/ OV, Cytogen Corp., Princeton, NJ) in a region of interest in the femoral vascular bundle to the uptake in two regions of interest in the lower abdomen, resulting in an uptake ratio (UR). All 29 patients underwent laparotomy after immunoscintigraphy. Of the 29 patients evaluated, 7 had histologically proven carcinomatosis obtained from the laparotomy. Using quantitative analysis, patients who did not have carcinomatosis had a mean uptake ratio of 1.12, and patients with carcinomatosis had a mean uptake ratio of 2.12. The differences between the means of these two groups of patients was statistically significant for all three technologists (P < .05). The results of this study indicate that there is a significant difference in uptake ratios between patients with carcinomatosis and those without it, and that quantitative analysis can be a useful adjunct to visual interpretation.

Monoclonal antibodies used in the detection and treatment of epithelial ovarian cancer

Conventional therapy for epithelial ovarian cancer, including aggressive cytoreductive surgery followed by combination chemotherapy regimens, has failed to reduce the number of deaths caused by this disease, which remains the most lethal of gynecologic malignancies. Monoclonal antibodies, which offer the promise of high selectivity for detection and therapy, may be targeted to tumor-associated antigens, growth factors, receptors, or oncogenes. They may be used alone as immunotherapeutic agents or conjugated to chemotherapeutic drugs, toxins, or radionuclides. Radioimmunoconjugates may also be used for preoperative or intraoperative tumor localization. The authors focused on the clinical utility, technical limitations, and potential of monoclonal antibodies in the detection and treatment of epithelial ovarian cancer with emphasis on radioimmunodetection and radioimmunotherapy.

Correlative imaging with monoclonal antibodies in colorectal, ovarian, and prostate cancer

Monoclonal antibody (MoAb) imaging has contributed greatly to the diagnosis and staging of both colorectal and ovarian cancers, and recently has been tested in patients with prostate cancer. Anatomic imaging modalities such as computed tomography, ultrasound, and magnetic resonance imaging have deficiencies in imaging each of these cancers that can be complemented or overcome by using radioimmunoscintigraphy. The management of patients with colorectal cancer, in particular, has been aided by developments in immunoscintigraphy. The new, safe, and easy-to-prepare MoAbs make possible an effective form of colon and rectal cancer imaging that has been used for (1) staging primary colorectal tumors in presurgical patients, (2) determining extent of disease, (3) continuing surveillance of patients at risk for recurrence of disease, (4) managing patients with elevated carcinoembryonic antigen levels (even those with otherwise negative workup results), and (5) imaging for occult, disease in patients both before and after surgery. In ovarian cancer patients, MoAbs are promising as safe, sensitive imaging tools. The U.S. Food and Drug Administration has approved 111In satumomab pendetide (OncoScint CR/OV; Cytogen Corporation, Princeton, NJ) for use in imaging colorectal and ovarian cancer. Immunoscintigraphy is being refined and tested to locate bony and soft-tissue metastases in patients with prostate cancer. As both a complementary tool and, in some cases, the imaging modality of choice, MoAbs have proven to be safe, accurate imaging tools for many patients with cancer.

Monoclonal antibodies in ovarian and prostate cancer

Radioimmunoscintigraphy (RIS)--using radiolabeled monoclonal antibodies (MoAbs) to image disease--is a growing subspecialty of nuclear medicine. RIS of the reproductive tracts of men and women has shown encouraging results in imaging both primary lesions and metastases of these cancers. Ovarian cancer is the most fatal gynecologic cancer in the United States, and prostate cancer is the most prevalent form of cancer in men. Several MoAbs against reproductive tumor antigens were used with limited success in clinical trials before 1989. Most recently, MoAbs CYT-103 (satumomab pendetide) and OV-TL 3 have shown promise as safe, sensitive imaging tools for ovarian cancer. Although to date more agents have been used to image ovarian carcinoma than prostate cancer, research has been restimulated in prostate carcinoma imaging because of development of a promising MoAb conjugate, CYT-356. Radionuclide indium-111 appears to be the most promising radiolabeled to date for ovarian and prostate carcinoma RIS performed in the United States. In future clinical trials, consideration of safety issues and a standardization of methods among institutions using RIS are needed before the use of MoAb technology in cancer imaging will become routine. Comparative studies with more traditional methods like computed tomography are needed, as well as more trials comparing radioimmunoscintigraphic findings with pathological evidence.