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Genetic profiles are able to help doctors determine which patients will probably develop cancer, and those who will most likely relapse. However, it cannot be suitable for specific treatments for individual patients.

The Microarray (gene chips) is a device that measures differences in gene sequence, gene expression or protein expression in biological samples. Microarrays may be used to compare gene or protein expression under different conditions, such as cells found in cancer.

It would be more advantageous to sort out what"s the best "profile" in terms of which patients benefit from this drug or that drug. Can they be combined? What"s the proper way to work with all the new drugs? If a drug works extremely well for a certain percentage of cancer patients, identify which ones and "personalize" their treatment. If one drug or another is working for some patients then obviously there are others who would also benefit. But, what"s good for the group (population studies) may not be good for the individual.

Patients would certainly have a better chance of success had their cancer been chemo-sensitive rather than chemo-resistant, where it is more apparent that chemotherapy improves the survival of patients, and where identifying the most effective chemotherapy would be more likely to improve survival above that achieved with "best guess" empiric chemotherapy through clinical trials.

Gene expression assays can be either probing for the specific RNA messengers (messenger RNA) or it can mean looking for the proteins themselves. Like testing breast cancer for the presence of hormone receptors and over-expression of growth factor receptors. However, most drugs cannot be looked at in this way and tests that are now in use have limited predictive accuracy.

It may be very important to zero in on different genes and proteins. However, when actually taking the "targeted" drugs, do the drugs even enter the cancer cell? Once entered, does it immediately get metabolized or pumped out, or does it accumulate? In other words, will it work for every patient?

All the validations of this gene or that protein provides us with a variety of sophisticated techniques to provide new insights into the tumorigenic process, but if the "targeted" 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, it just isn"t going to work.

To overcome the problems of heterogeneity in cancer and prevent rapid cellular adaptation, oncologists are able to tailor chemotherapy in individual patients. This can be done by testing "live" tumor cells to see if they are susceptible to particular drugs, before giving them to the patient. DNA microarray work will prove to be highly complementary to the parellel breakthrough efforts in targeted therapy through cell function analysis.

As we enter the era of "personalized" medicine, it is time to take a fresh look at how we evaluate new medicines and treatments for cancer. More emphasis should be put on matching treatment to the patient, through the use of individualized pre-testing.

Upgrading clinical therapy by using drug sensitivity assays measuring "cell death" of three dimensional microclusters of "live" fresh tumor cell, can improve the situation by allowing more drugs to be considered. The more drug types there are in the selective arsenal, the more likely the system is to prove beneficial.

Source: Cell Function Analysis

Chemotherapy Selection

Gene and Protein testing involve the use of dead, formaldehyde preserved cells that are never exposed to chemotherapy drugs. Gene and Protein tests cannot tells us anything about uptake of a certain drug into the cell or if the drug will be excluded before it can act or what changes will take place within the cell if the drug successfully enters the cell.

Gene and Protein tests cannot discriminate among the activities of different drugs within the same class. Instead, Gene and Protein tests assume that all drugs within a class will produce precisely the same effect, even though from clinical experience, this is not the case. Nor can Gene and Protein tests tell us anything about drug combinations.

"Whole Cell" Functional Tumor Cell Profiling tests living cancer cells. Functional Tumor Cell Profiling assesses the net result of all cellular processes, including interactions, occurring in real time when cancer cells actually are exposed to specific anti-cancer drugs. Functional Tumor Cell Profiling can discriminate differing anti-tumor effects of different drugs within the same class. Functional Profiling can also identify synergies in drug combinations.

Gene and Protein tests are better suited for ruling out "inactive" drugs than for identifying "active" drugs. When considering a cancer drug which is believed to act only upon cancer cells that have a specific genetic defect, it is useful to know if a patient's cancer cells do or do not have precisely that defect.

Although presence of a targeted defect does not necessarily mean that a drug will be effective, absence of the targeted defect may rule out use of the drug. Of course, this assumes that the mechanism of drug activity is known beyond any doubt, which is not always the case.

Although Gene and Protein testing currently are limited in their reliability as clinical tools, the tests can be important in research settings such as in helping to identify rational targets for development of new anti-cancer drugs.

As you can see, just selecting the right test to perform in the right situation is a very important step on the road to personalizing cancer therapy.