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Göttingen phase II-trial shows: One-time application of radio-labelled monoclonal antibody significantly increases life expectancy after excision of liver metastases
(ukg) Patients with colon cancer (colorectal carcinoma) have a higher life expectancy if treated once with the radioactively labelled anti-CEA-antibody I131-Labetuzumab after excision of liver metastases. This is the result of a joint phase II clinical trial at the University Göttingen Medical Faculty, Germany, and the Garden State Cancer Center for Molecular Medicine and Immunology in Belleville, NJ (USA).
Over a period of five years the researchers analyzed the course of disease and the survival of patients who had been treated once with the radio labelled monoclonal antibody Labetuzumab, after metastases of the liver had been resected. Labetuzumab detects and binds to smallest distant colonies of tumour metastases in the body. These meta-stases escape conventional examination techniques such as computer tomography or magnetic resonance imaging. The antibody was coupled with radioactive iodine, which eliminated cancerous cells on the spot (radio-immunotherapy, RAIT). The study was published on 20 Sept 2005 in the Journal of Clinical Oncology (vol. 23(27): pp 6763-70).
Of the 23 patients who where treated with I131-Labetuzumab, 19 were kept in the study. These patients survived for an average of 68 months, which was roughly twice as long as patients who had not received radio-immunotherapy. Five years after antibody treatment, half of the patients were still alive, while out of the control group of patients, only about one third had survived this period of time. A transient change in the blood picture was the most common of adverse effects observed.
"The trial gives us the best results to date for patients with a complete resection of liver metastases. The outcome encourages us to test the radio-immunological treatment in a phase III trail. Here, we will compare different therapies systematically on a greater scale", says Dr Torsten Liersch, Dept of General Surgery (director: Prof Dr Heinz Becker). Liersch conducted the trial together with PD Dr Johannes Meller (director of the Dept of Nuclear Medicine). Direct co-operation partner was the pioneer in radio-immunotherapy, Prof Dr David M Goldenberg, Garden State Cancer Center, NJ, USA. At present, the researchers are conducting trials in which they administer I131-Labetuzumab repeatedly to patients with colorectal carcinoma. The goal is to gain insight into positive as well as adverse effects of the drug after repeated drug administration.
Colorectal carcinoma is the third-most frequent tumour disease in industrial nations like Europe or the USA. Six out of ten patients develop liver metastases after initial cancer treatment. Despite chemo-therapeutic treatment, most of these patients die within few years. Only if liver metastases are removed quickly and completely is there a chance of healing. Approximately one out of three patients treated in this way survives at least five more years. Still, two out of three of these will develop yet another tumour. Most of these tumours are found in the liver.
Liver metastases most likely develop from clusters of undetected tumour cells that flow to the liver with the blood stream. Like colon carcinoma, nine out of ten of these metastases present on their surface a protein named CEA (Carcino-Embryonic Antigen). Tumour research aims at finding a way to use CEA as bait / anchor for antibodies to specifically destroy the micro-metastases (after the detectable metastases have been removed surgically).
Labetuzumab is a so-called humanized monoclonal antibody that was developed at Immunomedics Inc. (Morris Plains, NJ, USA). The antibody binds specifically to CEA, which is presented on the surface colon carcinoma and most of its metastases. A radioactively labelled variant of the antibody (radioactive iodine, I131) can trace down scattered tumour cell clusters in the body and destroy them on the spot. This has been proven in animal tests. As adverse effects, transient changes in the blood pictures have been observed, although the changes did not impair bone marrow function permanently.
Clinical trials are a prerequisite for the development and approval of pharmacotherapies. There are four phases in clinical trials. Phase II serves to evaluate the activity of a drug, and to provide information on how well a drug works. The number of patients is low. During phase III, controlled studies are conducted on as many patients as possible. Phase III is crucial for the official approval of a drug. The studies are meant to prove that a new drug is markedly better or at least as good as existing drugs in the treatment of a specific indication ("illness").
Further Information:
Faculty of Medicine - University of Göttingen
Department of General Surgery
Dr. Torsten Liersch
Robert-Koch-Str. 40
D-37075 Göttingen
Germany
Phone: +49-551 / 39-6104
E-mail: tliersc@gwdg.de
Faculty of Medicine - Georg-August-Universität Göttingen
Press- and Public Relations Office - Stefan Weller
Robert-Koch-Str. 42 - D-37075 Göttingen
Phone: +45-551/39 - 99 59 - Fax: +49-551/39 - 99 57
Mail: presse.medizin@med.uni-goettingen.de
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