19 April 2006

Finally! A Molecular Approach to Cancer Therapy

From my earliest days as a wet-behind-the-ears medical student, I have been dismayed at the labyrinthine treatment rules to the treatment of various cancers, depending on the site of origin. Oncology almost seemed like a glorified form of voodoo medicine. Now, with the arrival of better tools of cell and molecular biology being utilised in hospital labs, it is finally becoming possible to treat cancers rationally, based upon the actual molecular behaviour of the tumour itself.

This newsrelease from the Washington University School of Medicine in St. Louis, Missouri, provides more information into this better approach to oncology.

The researchers found that, independent of anatomical origin, some tumors had high amounts of irinotecan's cellular target, a protein labeled TOP1, while other tumors had very little. Irinotecan would likely be ineffective in tumors with low TOP1 levels. They also found that tumors varied greatly in the amounts of proteins that transport irinotecan into and out of their cells and in the amounts of proteins that break down irinotecan. These variations determine how well irinotecan will work in a particular tumor.

"Because tumor response can't be predicted from anatomical location, we should start selecting treatments based on what genes and proteins can tell us about how the tumor will respond to a drug," says McLeod, professor of medicine, of genetics, and of molecular biology and pharmacology. "If we rely just on what has clinically been shown to work in some cases for a particular anatomically defined cancer, we may not initially choose the best therapy for the individual patient. And with advanced cancer, a patient may get only one shot at the right therapy — making the wrong choice could be deadly."

According to McLeod, under current treatment selection methods virtually no chemotherapeutic drug has been successful in more than 50 percent of patients with advanced cancer. But instead of considering a drug that works only ten percent of the time a failure, he feels it would be better to consider such a drug effective for one in ten tumors and to search for the agents among the current arsenal of chemotherapeutic drugs that will work for the rest.

"We have more than 70 FDA-approved drugs that potentially could be useful for a particular tumor," McLeod says. "We are now working on methods that can be used to identify those drugs that will work for each patient's tumor."
Source.

Besides radically changing current oncology therapies, the new biological tools will also bring more effective drugs to the regulatory process more quickly. Treating cancer is beginning to seem a lot less like Voodoo Medicine, than it once did.

Labels:

Bookmark and Share

3 Comments:

Blogger Greg Pawelski said...

What a cancer patient would like ideally, is to know whether they would benefit from adjuvant chemotherapy (Molecular profiling). If so, which active drugs have the highest probability of working (Cellular profiling) and are relatively non-toxic in a given patient (Pharmacologic profiliig).

By utilizing Molecular profiling oncologists can identify those patients unlikely to benefit from adjuvant chemotherapy from those that would. If the patient needs adjuvant chemotherapy, utilizing Cellular and Pharmacologic profiling, the oncologist can select drugs that have a higher probability of being effective for an individual patient rather than selecting drugs based on the average responses of many patients in large clinical trials.

It's not one versus the other. The best thing is to combine these different tests in ways which make the most sense. One month's worth of herceptin + avastin costs approximately $8000. That's without any docetaxel and blood cell growth factors and anti-emetics. If nothing else, we can't afford too much trial and error treatment.

There are patients who have progressive disease after first-line therapy, only to enjoy a dramatic benefit from second or even third line therapy, and these patients would have been much better served by receiving the most probable active treatment "the first time around."

There should an expansion of reimbursement to promote even greater utilization and development of these laboratory-based mechanisms for improving the match between tumors and an ever-increasing number of partially effective and very expensive drug therapies.

These laboratory tests are a tool for the oncologist. The oncologist should take advantage of all the tools available to him/her to treat a patient. And since studies show that only 25-30% of patients do respond to chemotherapy that is available to them, there should be due consideration to looking at the advantage of these tests to the resistance that has been found to chemotherapy drugs.

Wednesday, 19 April, 2006  
Blogger al fin said...

Well put, thanks.

I might add that there is more information available at the link provided in the article.

Thursday, 20 April, 2006  
Blogger Greg Pawelski said...

Whole Cell Profiling

The introduction of new "targeted" drugs has not been accompanied by specific predictive tests allowing for a rational and economical use of the drugs. Given the technical and conceptual advantages of Cell Culture Drug Resistance Tests (CCDRTs) together with their performance and the modest efficicay of therapy prediction on analysis of genome expression, there is reason for a renewal in the interest for CCDRTs for optimized use of medical treatment of malignant disease.

Clinical study results published at the annual meeting of the American Society of Clinical Oncology (ASCO) show that a new laboratory test, called EGFRx (TM), has accurately identified patients who would benefit from treatment with the molecularly-targeted anti-cancer therapies. The finding is important because the EGFRx (TM) test, which can also be applied to many emerging targeted cancer drugs, could help solve the growing problem of knowing which patients should receive costly, new treatments that can have harmful side-effects and which work for some but not all cancer patients who receive them. The 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.

The new test relies upon what is called "Whole Cell Profiling" in which living tumor 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 combined 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.

The whole cell profiling method makes the statistically significant association between prospectively reported test results and patient survival. Using the EGFRx (TM) assay and the whole cell profiling method, 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.

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 has been described that can discriminate differing levels of anti-tumor activity occurring among different targeted therapy drugs. 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 cell 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.

The whole 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.

Genomic testing is not the answer, without cell culture analysis. In developing a program to discover gene expression microarrays, which predict for responsiveness to drug therapy, the way to identify informative gene expression patterns is to have a gold standard and that cell culture assays are by far the most powerful, efficient, useful gold standard to have.

The 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 (includes newly-emergent drug combinations).

http://www.weisenthal.org/newsrelease060608v1.htm

Thursday, 29 June, 2006  

Post a Comment

“During times of universal deceit, telling the truth becomes a revolutionary act” _George Orwell

<< Home

Newer Posts Older Posts
``