Investigation of 3'-debenzoyl-3'-(3-([¹²4I]-iodobenzoyl))paclitaxel analog as a radio-tracer to study multidrug resistance in vivo.

A study was carried out to identify a suitable radioactive paclitaxel analog and to use it to investigate tumor multidrug resistance in vivo. 3'-Debenzoyl-3'-(3-([(124)I]-iodobenzoyl))paclitaxel was prepared by aromatic iodination of 3'-debenzoyl-3'-(3-trimethylstannylbenzoyl)paclitaxel. Uptake of the labeled paclitaxel analog in nude mice bearing tumor with the paclitaxel sensitive cancer cell lines MCF7 and MDA-435/LCC6(WT), and multidrug resistant cell lines NCI/ADR-RES and MDA-435/LCC6(MDR), was studied. There was no difference in drug level between the sensitive and resistant MDA-435/LCC6 tumors at 6h post-injection. However, at 6h, there was a significant increase in drug level for the MCF7 tumor as compared with the NCI/ADR-RES tumor, presumably due to increased drug retention. At 24h, drug uptake/retention was significantly higher in both sensitive tumor cell lines as compared to their drug resistant counterparts. Pretreatment of mice with MDR transport modulators, Cyclosporine or tRA 96029, did not increase the level of labeled paclitaxel analog in the drug resistant MDA-435/LCC6(MDR) tumor. On the other hand, at 24h Cyclosporine apparently increased analog level in the drug sensitive MDA-435/LCC6(WT) tumor, aiding drug imaging studies.

Clinical and technical considerations for imaging colorectal cancers with technetium-99m-labeled antiCEA Fab' fragment.

OBJECTIVE: Colorectal cancer is the third most common cancer, after lung and breast cancers. Approximately 133,500 Americans develop colorectal cancer annually and approximately 54,900 die of the disease. As many as 600,000 individuals in the US are under care after surgery for colorectal cancer. After reading this article, the nuclear medicine technologist will be able to: (a) describe the role of Arcitumomab in evaluating and managing patients with recurrent colorectal carcinoma metastasizing to the liver; (b) discuss the clinical use of CEA-Scan (Immunomedics, Inc., Morris Plains, NJ) and its overall imaging performance characteristics and sensitivity related to specific anatomical sites compared to conventional diagnostic modalities; (c) describe radiopharmaceutical preparation and quality control; (d) identify the pertinent patient history before starting the test; and (e) explain the imaging procedure, processing and display of data to optimize study interpretation.

Superiority of SPET to planar imaging in the detection of colorectal carcinomas with 111In monoclonal antibodies.

The aim of this study was to assess the contribution of single photon emission tomography (SPET) to planar imaging of colorectal carcinoma in patients being evaluated with 111In-labelled monoclonal antibodies CYT-103 (OncoScint CR/OV) or IVP ZCE 025. Planar and SPET scans from 110 colorectal carcinoma patients were scored individually as follows: 1=negative, 2=equivocal, 3=positive. The planar and SPET images identified 67 and 93 of 113 documented lesions, respectively. The planar and SPET findings were concordant in 55 patients. SPET converted planar findings from 1 to 3 in 11 patients and from 2 to 3 in 21 patients. SPET provided a better definition of the extent of the tumour in 21 patients. Both imaging tests were true-negative in five patients, and failed to detect tumours in six patients. We strongly recommended SPET in all patients undergoing immunoscintigraphy, since it identified tumours missed on planar scans in 35% of patients and provided additional information regarding tumour burden in 23% of patients.