PET/Computed Tomography for Radiation Therapy Planning of Prostate Cancer.

This article is a short review of PET tracers, which have been used in clinical routine in single institutions. Preliminary anecdotal research supports the use of PET techniques in therapy planning of prostate cancer. The existing literature is discussed. For external beam radiation therapy, the biological target volume definition can only be based on PET imaging. There are not yet any prospective and randomized trials available; therefore, single-institution experiences cannot yet be recommended as clinical routine.

Indium-111-bleomycin complex in squamous cell cancer xenograft tumors of nude mice.

INTRODUCTION: Labeling of bleomycin with Auger-emitter Indium-111 increases cytotoxicity in squamous cell cancer (SCC) cell lines, as we have reported earlier. In this study, we investigated whether (111)In- BLMC is toxic and effective in vivo among SCC-xenografted mice. The influence of (111)InBLMC on the squamous cell carcinoma cell cycle stimulated interest. MATERIALS AND METHODS: In an animal experiment, 10 SCC-xenografted mice were used, two for demonstrating targeting in gamma-camera images, eight for intraperitoneally receiving NaCl, BLM, or (111)InBLMC as therapy. After a 2-week follow-up, the tumors were analyzed for proliferation (mitoses, Ki-67). DNA flow cytometric analysis was carried out from tumor samples and three UT-SCC cell lines. RESULTS: Tumors were observed on gamma-camera images in xenografted mice after a (111)InBLMC injection. The UT-SCC-19A-xenografted mouse had a T/non-T uptake of 7.54 at 4 hours after the injection. At the end of the therapeutic trial, the mice were alive. In spite of a small number of animals, our findings indicate that BLM and (111)InBLMC seem to be more effective than NaCl in reducing tumor size. The proliferative activity was strong in BLM and in (111)InBLMC groups, indicating regrowth of the tumors. In DNA analysis, the percentages of cells in the G2/M-phases increased after exposure to BLM and particularly to (111)InBLMC in all three cell lines. CONCLUSIONS: The effect of BLM is preserved after the adding of Auger-emitter In-111. Tumor-seeking (111)InBLMC can be administered safely at tumor-decreasing concentrations in xenograft head and neck cancers. To demonstrate the antitumor effect of (111)InBLMC, the experiments should be extended to include a larger number of mice. BLM, and especially (111)InBLMC, seems to induce alteration in the cell cycle by producing a G2/M block. The verification of the result requires repeated in vitro experiments.

Radiolabeled compounds in the development of cytotoxic agents.

With the help of radiolabeled compounds, drug development can be made faster; especially with microdosing and radiopharmacokinetics, some elements of phase I and II trials necessary for conventional cancer drug development can be avoided. Imaging may proof the principle of actual targeting. However, radiopharmacokinetics is dependent on the radionuclide, the radionuclide linker with the drug and the size of the drug molecule. Optimally, some of the drug molecule atoms may be replaced with a radionuclide that can be visualized. In this article drug development utilizing radionuclides both in PET and SPET has been reviewed.

Radioimmunodetection and radioimmunotherapy of head and neck cancer.

Radiolabeled monoclonal antibodies (MAbs) can add a dimension to diagnostic imaging and staging of metastatic head and neck cancer, as well as in eradication of this disease. The vast majority of malignancies arising in the oral cavity, pharynx and larynx are squamous cell carcinomas. This common cellular origin makes it attractive to search for appropriate tumor-associated antigens, which are preferentially expressed in these neoplasms. Radiolabeled MAbs directed against these antigens can be used for tumor detection and selective therapy, known as radioimmunoscintigraphy and radioimmunotherapy, respectively. The combination of MAbs with positron emission tomography (PET) is an attractive novel option to improve tumor detection and to facilitate MAb quantification in a therapeutic setting. Basic aspects of tumor targeting with MAbs, as well as a review of the clinical trials reported in the literature, including own results, are presented.

Anti-alpha-fetoprotein imaging is useful for staging hepatoblastoma.

BACKGROUND: Liver transplantation (Tx) has become an alternative treatment of malignant childhood liver tumors, and the importance of careful pretransplantation evaluation has been emphasized. Anti-alpha-fetoprotein (AFP) imaging has been suggested for evaluation of adult patients with AFP-positive tumors. METHODS: Antibody imaging utilizing Tc-99 m-labeled monoclonal anti-AFP Fab' fragments was used to demonstrate pathologic uptake in hepatoblastoma (HB). RESULTS: Radical operation or liver Tx was not possible after four cycles of chemotherapy in a child with HB because of a single extrahepatic metastasis. Chemotherapy was continued, and reevaluation with anti-AFP imaging demonstrated a pathologic uptake only in the liver. Subsequently, a right liver lobe resection was performed. Along with a new rise in serum AFP, repeated anti-AFP imaging revealed active liver tumor but no metastases. A liver Tx was performed, and the child is well with a normal serum AFP level 18 months after the operation. CONCLUSION: This is the first case of pediatric HB in which anti-AFP imaging has been successfully used for patient management.