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Proteins Show Promise As Cancer Treatment Tool; Proteomics Also Could Help Guide Cancer Drug Development, Study Finds

Posted on: Thursday, 25 August 2005, 15:00 CDT

A recent study by the Cancer Therapy & Research Center (CTRC) demonstrated the potential of focusing on an individual's protein composition, and levels of certain proteins associated with particular cancers, to both predict cancer susceptibility and help determine the most effective therapy for that individual.

The pilot study shows a correlation between levels of certain proteins in human tumor cells and the effectiveness of two of the most common chemotherapy drugs for lung, prostate and breast cancer. Results of the study are published in the July-August issue of "Cancer Genomics & Proteomics."

Researchers tested docetaxel (Taxotere(R)) and paclitaxel (Taxol(R)), common cancer drugs that inhibit cell growth by stopping cell division. Docetaxel was found to be superior to paclitaxel in inhibiting growth of human lung and prostate cancer cells that had low levels of Bcl-2, an "anti-death" protein that protects cancer cells and allows them to multiply. Yet docetaxel was no more effective than paclitaxel against breast cancers, which showed high levels of Bcl-2. Current observation on notable impact of docetaxel in tumors with little Bcl-2 warrants further study of biomarkers for drug sensitivity as well as investigation of docetaxel in combination with drugs that reduce Bcl-2 levels, according to Dr. Elzbieta Izbicka, of the CTRC's Institute for Drug Development.

The researchers also used a sensitive method for protein profiling to identify a potential biomarker for docetaxel response. However, more work is needed to translate the findings from preclinical experiments in cells grown in culture and animal models to the clinical setting.

"These early findings provide a proof of concept that through proteomic profiling we may be able to identify biomarkers that exist in certain cancer types and not others," explained Izbicka. "By better understanding drug effects in cell culture and animal models of human cancers, there is incredible potential to find new opportunities for targeted drug development as well as detection and treatment of cancer based on protein profiling. An individual's Bcl-2 level might turn out to be an important determinant of docetaxel sensitivity and therefore help determine the most effective course of therapy for that particular patient. Other biomarkers may be equally important."

Proteomics, the systematic study of the proteins in a cell, tissue or organism, is an emerging area of investigation in the pursuit of new treatments for cancer. To date, only a tiny percentage of the more than one million different protein forms in human cells have been sequenced or identified. Fewer still have been studied in relation to cancer treatment.

However, proteomics is expected to be increasingly used in cancer diagnosis and treatment, which involves searching for proteins that may serve as biomarkers of early disease, of responsiveness to therapy, or of the likelihood of relapse after treatment, Izbicka said.

The CTRC study was conducted by Izbicka, David Campos, Gilbert Carrizales, and Dr. Anthony Tolcher of the Institute for Drug Development.

CTRC is one of the nation's premier cancer research and treatment centers. Thirteen of the last 17 FDA-approved anti-cancer agents underwent development or testing by CTRC scientists and doctors. We are a first choice for cancer treatment -- our teams of world-class physicians and staff use the latest technology and drugs to provide individualized care for our patients and their families.

Source: Business Wire

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