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Print ArticleStudying the gene-expression profiles of patients with colorectal cancer might help predict their response to chemotherapy. In a study published today in the open access journal Genome Biology, researchers identified in the tumours of colorectal cancer patients almost 700 genes whose expression was different between patients who subsequently responded well to combined chemotherapy and patients who were resistant to the therapy. These findings could be used in clinical practice to complement clinical, biochemical and genetic markers for better treatment of patients with colorectal cancer.
A research group led by Sandrine Imbeaud from the CNRS and Pierre and Marie Curie University, Villejuif, France, used microarrays to analyse the gene-expression patterns of samples from colon tumours and liver metastases collected from 13 patients with colorectal cancer. The microarray analyses were carried out before the patients were treated with combined chemotherapy of folinic acid, 5-fluorouracil and irinotecan.
Imbeaud and colleagues identified 679 genes that were differently expressed in patients who subsequently responded well to chemotherapy compared with patients who were resistant to the therapy. The results were validated by RT-PCR analysis, which confirmed the differential expression of 22 genes selected from the list. The findings were also confirmed by RT-PCR analysis of colon and liver tumour samples collected from two additional patients.
The authors were able to integrate their findings into global and interconnected molecular networks that characterise resistance in patients with colorectal cancer before they are exposed to chemotherapy. They conclude that knowledge of these networks could potentially be used to improve diagnosis and treatment of patients with colorectal cancer.
Source : BioMed Central
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Functional profiling (whole cell profiling) with cell culture assays for targeted drug therapy
Recent findings presented at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium in Orlando, Florida concluded that Functional Profiling (whole cell profiling) with cell culture assays is relevant for the study of both "conventional" and "targeted" antineoplastic drug agents.
Cell Culture Assays with "cell-death" endpoints can show disease-specific drug activity, are useful clinical and research tools for "conventional" and "targeted" drugs, and provide unique information complementary to that provided by "molecular" tests. There have been more than 25 peer-reviewed publicatons showing significant correlations between cell-death assay results and patient response and survival.
The Whole Cell Profiling technique is a cell-death endpoint assay in which drug effect upon cancer cells is visualized directly. Photomicrographs of actual tumor cells sometime show that the exact same identical individual culture well, shows some clusters have taken up vast amounts of a drug, while right next door, clusters of the same size, same appearance, same everything haven't taken up any of the drug.
So it doesn't matter if there is a "target" molecule (protein or receptor) in the cell that the targeted drug is going after, if the drug either won't "get in" in the first place or if it gets pumped out/extruded or if it gets immediately metabolized inside the cell, drug resistance is multifactorial. The advantage of the Whole Cell Profiling technique is that it can show this in the "population" of cells.
The Whole Cell Profiling technique makes the statistically significant association between prospectively reported test results and patient survival. It can correlate test results which are obtained in the lab and reported to physicians prior to patient treatment, with significantly longer or shorter overall patient survival depending upon whether the drug was found to be effective or ineffective at killing the patient's tumor cells in the laboratory.
This could help solve the problem of knowing which patients can tolerate costly, new treatments and their harmful side-effects. These "smart" drugs are a really exciting element of cancer medicine, but do not work for everyone, and a test to determine the efficacy of these drugs in a patient could be the first crucial step in personalizing treatment to the individual.
Functional profiling (FP) with cell culture assays for targeted drug therapy.
Sub-category: Translational research
Category: Colon and Rectum
Meeting: 2007 Gastrointestinal Cancers Symposium
Abstract No: 440
Author(s): L. M. Weisenthal
Abstract: Introduction: We studied the relevance of FP for standard and targeted drugs.
Methods: Drugs were tested against fresh human tumor microclusters, with 96 hr drug exposures and multiple FP endpoints (MTT, DISC, resazurin, and/or ATP).
Results: In 65 previously chemonaive stage 4 colon cancer patients, those with FP assays showing 5FU results in the most resistant tertile had inferior overall survival, compared to pts without 5FU resistance (303 days vs. 686 days, H.R. 2.1, 95% C.I. 1.2 - 5.0, P2=0.011). In subset analysis restricted only to 53 pts who subsequently died (eliminating potential surgical cures), the respective results were 292 vs 493 days, HR 1.5 - 6.9, P2=0.0021. We applied FP to test targeted agents, including gefitinib, erlotinib, sunitinib, sorafenib, and bevacizumab. Gefitinib was tested against > 700 fresh tumor specimens; we reported striking correlations between gefitinib activity and overall pt survival in non-small lung cancer (2006 ASCO Annu Mtg, Abst 17117). Gefitinib and erlotinib are moderately cross resistant (R2=0.48, n paired comparisons=190). Gefitinib/sunitinib (R2=0.20, n=46) and erlotinib/sunitinib (R2=0.12, n=44) are largely non-cross resistant. We also developed a new microvascular viability assay (MVVA) to test microvascular cells present in tumor clusters. In the MVVA, bevacizumab was tested in 81 fresh tumor specimens (including 15 GI). Bevacizumab was nontoxic to the tumor cells, but often strikingly toxic to microvascular cells present within the same tumor clusters. Grading on a 0-4 scale, there was absent (Gr 0) effect in 23 specimens, weak (Gr 1-2) effect in 28, and a strong (Gr 3-4) effect in 26. In contrast to bevacizumab, neither sunitinib (n=87) nor sorafenib (n=20) showed selective effects against microvascular cells compared to tumor cells.
Conclusions: We cannot rule out a cytostatic effect of sunitinib or sorafenib on tumor microvascular cells. However, our results imply that the antitumor effects of bevacizumab are predominately mediated through antimicrovascular effects, while effects of sunitinib and sorafenib may be mediated largely through tumor cell apoptosis. We conclude that FP is relevant for the study of both traditional and targeted antineoplastic agents.
http://www.asco.org/portal/site/ASCO/menuitem.64cfbd0f85cb37b2eda2be0aee37a01d/?vgnextoid=09f8201eb61a7010VgnVCM100000ed730ad1RCRD&vmview=vm_search_results_view&selectedConfs=&SearchFilter=Speaker&SearchTerm=weisenthal
Click on "Slides" to presentation relating to testing for antitumor and antiangiogenic activity of gefitinib, erlotinib, sunitinib, sorafenib, and bevacizumab in primary cultures of fresh human tumors.
Today’s treatments for cancer, namely the molecularly-targeted anti-cancer therapies like Avastin, Iressa, Tarceva and Sutent, are a vast improvement on treatments of ten years ago. These so-called "smart drugs" focus their effects on specific, identifiable processes occurring within cancer cells.
Normally chemotherapy kills both cancer cells and healthy normal cells (mainly rapidly-dividing cells). Oncologists try to minimize damage to normal cells and to enhance the cell-killing effect on cancer cells. Too often, this delicate balance is not achieved.
Targeted therapy drugs interfere with specific molecules (receptors and enzymes inside and outside a cancer cell). By focusing on these molecular and cellular changes, targeted cancer drugs go after the "target" in these cells, rather than just all cells. Because of this, "targeted" drugs may be more effective than current treatments, and may be less harmful to normal cells.
The new drugs are highly promising in that they sometimes provide benefit to patients who have failed traditional therapies. However, the therapies do not work for everyone, at least not as effectively, they often have unwanted side effects, are all extremely expensive, and a test to determine the efficacy of these drugs in a patient could be the first crucial step in personalizing treatment to the individual. Patients, physicians, insurance carriers, and the FDA are all calling for the discovery of predictive tests that allow for rational and cost-effective use of these drugs.
The EGFRx assay will test molecularly-targeted anti-cancer drugs therapies Iressa, Tarceva, Sutent and Nexavar, because of being small molecules. The monoclonal antibodies like Herceptin and Erbitux are "enormous" molecules. These very large molecules don't have a convenient way of getting access to the large majority of cells. Plus, there is multicellular resistance, the drugs affecting only the cells on the outside may not kill these cells if they are in contact with cells on the inside, which are protected from the drug. The cells may pass small molecules back and forth.
However, drugs like Avastin (although a monoclonal antibody) can be tested with EGFRx because the target of Avastin is not the cells themselves, but rather a hormone (VEGF) secreted by the tumor cells. The Avastin complexes with free VEGF and blocks its action. The EGFRx test can discriminate between the activity of different targeted drugs and identify situations in which it is advantageous to combine the targeted drugs with other types of cancer drugs. Most patients are treated not with a targeted therapy drug alone but with a combination of chemotherapy drugs.
The EGFRx Assay measures the net effect of everthing which goes on (Whole Cell Profiling). Are the cells ultimately killed, or aren't they? Basically, Whole Cell Profiling measures the response of the tumor cells to drug exposure. Following this exposure, it measures both cell metabolism and cell morphology. The effect of drugs on the whole cell, resulting in a cellular response to the drug, measures the interaction of the entire genome.
A variety of metabolic and apoptotic measurements are then used to determine if a specific drug was successful at killing the patient's cancer cells. The Whole Cell Profiling method differs from other tests in that it assesses the activity of a drug upon combined effect of all cellular processes, using several metabolic (cell metabolism) and morphologic (structure) endpoints, at the cell "population" level (rather than at the "single cell" level).
Not only is this an important predictive test that is available, but it is also a unique tool that can help to identify newer and better drugs, evaluate promising drug combinations, and serve as a "gold standard" correlative model with which to develop new DNA, RNA, and protein-based tests that better predict for drug activity.
The EGFRx assay holds the key to solving some of the problems confronting a healthcare system that is seeking ways to best allocate available resources while accomplishing the critical task of matching individual patients with the treatments most likely to benefit them. Not only is it an important predictive test, it is also a unique tool that can help to identify newer and better drugs, evaluate promising drug combinations, and serve as a "gold standard" correlative model with which to develop new DNA, RNA, and protein-based tests that better predict for drug activity.
The EGFRx Assay is the only assay that involves direct "visualization" of the cancer cells at endpoint. This allows for accurate assessment of drug activity, discriminates tumor from non-tumor cells, and provides a permanent archival record, which improves quality, serves as control, and assesses dose response in vitro.
Source: http://weisenthal.org/ex_targeted_egfr_kinase.pdf
cool
A new laboratory test that identifies patients who benefit most from targeted cancer drugs was introduced at the annual meeting of the American Society of Clinical Oncology (ASCO) as the test's accuracy is sure to save hundreds of lives per year. This could help solve the problem of knowing which patients can tolerate costly, new treatments and their harmful side-effects. This "smart" drugs do not work for everyone, and a test to determine the efficacy of these drugs in a patient could be the first crucial step in personalizing treatment to the individual.
According to Chemical & Engineering News, targeted "small-molecule" therapies ruled at the annual ASCO meeting of oncologists. The most exciting results shown came from studies of multitargeted tyrosine kinase inhibitors, small molecules that act on multiple receptors in the cancerous cells, like Tykerb and Sutent. The trend is away from the monoclonals to the small molecules, a trend which the new EGFRx (TM) test may be able to hasten.
The EGFRx (TM) assay will test molecularly-targeted anti-cancer drugs therapies Iressa, Tarceva, Sutent and possibly Nexavar, because of being small molecules. The monoclonal antibodies like Herceptin and Erbitux are "enormous" molecules. These very large molecules don't have a convenient way of getting access to the large majority of cells. Plus, there is multicellular resistance, the drugs affecting only the cells on the outside may not kill these cells if they are in contact with cells on the inside, which are protected from the drug. The cells may pass small molecules back and forth.
However, drugs like Avastin (although a monoclonal antibody) can be tested with EGFRx (TM) because the target of Avastin is not the cells themselves, but rather a hormone (VEGF) secreted by the tumor cells. The Avastin complexes with free VEGF and blocks its action. The EGFRx (TM) test can discriminate between the activity of different targeted drugs and identify situations in which it is advantageous to combine the targeted drugs with other types of cancer drugs. All the more reason to "test the tumor first."
Most patients are treated not with a targeted therapy drug alone but with a combination of chemotherapy drugs. Therefore, existing DNA and RNA tests do not reflect the way cancer medicine is practiced today. The EGFRx assay, developed by The Weisenthal Cancer Group relies upon a technique known as "Whole Cell Profiling" in which living tumour cells are removed from an individual cancer patient and exposed in the laboratory to the new drugs.
A variety of metabolic and apoptotic measurements are then used to determine if a specific drug was successful at killing the patient's cancer cells. The whole cell profiling method differs from other tests in that it assesses the activity of a drug upon combined effect of all cellular processes, using several metabolic and morphologic endpoints. Other tests, such as those which identify DNA or RNA sequences or expression of individual proteins often examine only one component of a much larger, interactive process.
"Over the past few years, researchers have put enormous efforts into genetic profiling as a way of predicting patient response to targeted therapies. However, no gene-based test as been described that can discriminate differing levels of anti-tumour activity occurring among different targeted therapy drugs," said Larry Weisenthal, a medical oncologist and developer of the EGFRxTM assay."Nor can an available gene-based test identify situations in which it is advantageous to combine a targeted drug with other types of cancer drugs. So far, only whole profiling has demonstrated this critical ability."
Not only is this an important predictive test that is available "today," but it is also a unique tool that can help to identify newer and better drugs, evaluate promising drug combinations, and serve as a "gold standard" correlative model with which to develop new DNA, RNA, and protein-based tests that better predict for drug activity.
These "targeting" drugs are expensive, costing patients and insurance carriers $5,000 to $7,000 or more per month of treatment. Patients, physicians, insurance carriers, and the FDA are all calling for the discovery of predictive tests that allow for rational and cost-effective use of these drugs.
Weisenthal believes that the cell profiling approach, holds the key to solving some of the problems confronting a healthcare system that is seeking ways to best allocate available resources while accomplishing the critical task of matching individual patients with the treatments most likely to benefit them.
http://www.weisenthal.org/newsrelease060608v1.htm
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