Chemosensitivity Testing

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Chemosensitivity Testing

by Gdpawel on Wed Oct 13, 2004 12:00 AM

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When a patient has an infection, doctors often send a sample of infected blood or tissue to a lab where they can grow the bacteria and see which antibiotics are most effective. Chemosensitivity testing is an attempt to do something similar for cancer; fresh samples of the patient's tumor from surgery or a biopsy are grown in test tubes and tested with various drugs. Drugs that are most effective in killing the cultured cells are recommended for treatment. It is highly desirable to know what drugs are effective against your particular cancer cells before highly-toxic agents are systemically administered to your body. One approach to individualizing patient therapy is chemosensitivity testing. Chemosensitivity assay is a laboratory test that determines how effective specific chemotherapy agents are against an individual patient's cancer cells. Often, results are obtained before the patient begins treatment. This kind of testing can assist in individualizing cancer therapy by providing information about the likely response of an individual patient's tumor to proposed therapy. Chemosensitivity testing may have utility at the time of initial therapy, and in instances of severe drug hypersensitivity, failed therapy, recurrent disease, and metastatic disease, by providing assistance in selecting optimal chemotherapy regimens. All available chemosensitivity assays are able to report drug "resistance" information. Resistance implies that when a patient's cancer cells are exposed to a particular chemotherapy agent in the laboratory, the cancer cells will continue to live and grow. Some chemosensitivity assays also are able to report drug "sensitivity" information. Sensitivity implies that when a patient's cancer cells are treated with a particular chemotherapy agent in the laboratory, that agent will kill the cancer cells or inhibit their proliferation. The goal of all chemosensitivity tests is to determine the response of a patient's cancer cells to proposed chemotherapy agents. Knowing which chemotherapy agents the patient's cancer cells are resistant to is important. Then, these options can be eliminated, thereby avoiding the toxicity of ineffective agents. In addition, some chemosensitivity assays predict tumor cell sensitivity, or which agent would be most effective. Choosing the most effective agent can help patients to avoid the physical, emotional, and financial costs of failed therapy and experience an increased quality of life. Fresh samples of the patient's tumor from surgery or a biopsy are grown in test tubes and tested with various drugs. Drugs that are most effective in killing the cultured cells are recommended for treatment. Chemosensitivity testing does have predictive value, especially in predicting what "won't" work. Patients who have been through several chemotherapy regimens and are running out of options might want to consider chemosensitivity testing. It might help you find the best option or save you from fruitless additional treatment. Today, chemosensitivity testing has progressed to the point where it is 85% - 90% effective. Chemosensitivity testing might help you find the best option, or save you from fruitless additional treatment. Another situation where chemosensitivity testing might make particularly good sense is in rare cancers where there may not be enough experience or previous ideas of which drugs might be most effective. Finally, there has been a veritable deluge of new approvals of cytotoxic drugs in recent years as the tortuous FDA process has been speeded and liberalized. In many cases a new drug has been approved on the basis of a single very very narrow indication. But these drugs may have many useful applications - and it's going to take years to find out. Chemosensitivity testing offers a way of seeing if any of these new drugs might apply to your specific cancer. Another Name Cell Culture Drug Resistance Testing refers to laboratory testing of a patient's own cancer cells with drugs that may be used to treat the patient's cancer. A group of lab tests known as human tumor assay systems (HTAS) can aid oncologists in deciding which chemotherapies work best in battling an individual patient's form of cancer. The assay is a lab test performed on a biopsy specimen containing living cancer cells. It's used to determine the sensitivity or resistance of malignant cells to individual chemotherapy agents. Depending on how well the tumor cells respond to each chemotherapy agent, they are rated as sensitive, resistant or intermediate to chemotherapy. The concept is that you are better off using a chemotherapy drug that your tumor reacts to strongly than one your tumor resists. There have been over 40 publications in peer-reviewed medical literature showing correlations between cell-death assay test results and the results of clinical chemotherapy in more than 2,000 patients. In every single study, patients treated with drugs active in the assays had a higher response rate than the entire group of patients as a whole. In every single study, patients treated with drugs inactive in the assays had lower response rates than the entire group of patients. In every single study, patients treated with active drugs were much more likely to respond than patients treated with inactive drugs, with assay-active drugs being 7 to 9 times more likely to work than assay-inactive drugs. A large number of peer-review publications also reported that patients treated with assay-tested "active" drugs enjoyed significantly longer survival of cancer than patients with assay-tested "negative" drugs. Listing of "Reputable" Labs USA: These labs will provide you and your physician with in depth information and research on the testing they provide. Analytical Biosystems, Inc., Providence, Rhode Island. Ken Blackman, PhD. Solid Tumors Only. 1-800-262-6520 Anticancer, Inc., San Diego, CA. Robert Hoffman, PhD. Solid Tumors Only. 1-619-654-2555 Impath, Inc., New York, NY. David Kern, MD Solid Tumors and Hematologics. 1-800-447-8881 Oncotech, Inc., Irvine, CA. John Fruehauf, MD. Solid Tumors and Hematologics. 1-714-474-9262 / FAX 1-714-474-8147 Sylvester Cancer Institute, Miami, FL. Bernd-Uwe Sevin, MD. Solid Tumors Only. (especially GYN). 1-305-547-6875 Human Tumor Cloning Laboratory, San Antonio, TX. Daniel D. Von Hoff, MD. Solid Tumors Only. 1-210-677-3827 Rational Therapeutics Institute, Long Beach, CA. Robert A. Nagourney, MD Solid Tumors and Hematologics. 562-989-6455 http://www.rational-t.com/ DiaTech Oncology, Brentwood, TN. Vladimir D. Kravtsov, MD, PhD Medical Director 1-615-294-9033 Weisenthal Cancer Group, Huntington Beach, CA. Larry M. Weisenthal, MD, PhD. Solid Tumors and Hematologics. 1-714-894-0011 / FAX 1-714-893-3659 / e-mail: mail@weisenthal.org

Assay-directed Clinical Trials

by Gdpawel on Sat Jan 14, 2006 12:00 AM

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There was a summary paper from a National Cancer Institute study, presented at the American Society of Clinical Oncologists (ASCO) Annual Conference in 1998, which looked at thirteen different studies that searched into "in vitro" (chemosensitivity assay) drug sensitivity testing for patients with cancer. It was noted that with the many different cancers represented in these studies, chemotherapy response rates went up from 3 to 66% (using standard chemotherapy drugs and procedures) and from 21 to 81% (using "in vitro" testing for the most responsive drug) and patient survival increased from 4.5 to 11.2 months (using standared procedures) and from 6.2 to 38.5 months (using "in vitro" testing).

Dr Ian Cree, Director, Translational Oncology Research Centre, Queen Alexandra Hospital, Portsmouth UK performed the very first prospective, randomized clinical trial of physician's choice chemotherapy versus ATP assay-directed chemotherapy in non-surgically debulked, platinum-resistant ovarian cancer and presented it at the May, 2005 American Society of Clinical Oncologists (ASCO) meeting in Orlando, Florida.

The results were highly suggestive of an effect due to the assay, and the most successful drug regimens used were nearly all developed using the assay. UK results in cancer are always lower than in the US for a variety of reasons. Part of this is probably lead time bias, but data on surgical debulking may be part of the explanation. Patients in the US get a whole lot more surgery along the way than in Europe.

As a result of this, the Gynecologic Oncology Group (GOG) has decided to move forward with a study in platinum-resistant ovarian cancer, utilizing a different assay called EDR, to direct chemotherapy. However, this assay is specifically designed to identify 'inactive' rather than 'active' drugs. In this light, the EDR assay has the advantage of telling you who will 'not respond' but cannot in any way change the negative outcome by selecting an 'active' alternative. At least it's a start!

There are other medical oncologists in the US, headed up by Drs Larry Weisenthal and Robert Nagourney, that are making proposals for a separate study, a front-line randomized trial with head to head comparison of several assays (EDR, ATP, DISC, MTT, as well as Caspase 3/7). These assays correlate very well with each other on direct comparisons of different methods. Different methods of assay results should be applied in choosing a particular drug regimen to be used in treating an individual patient's cancer.

National Cancer Institute's Feeble Attempt at Assay-directed Therapy

by Gdpawel on Sat Jun 24, 2006 12:00 AM

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Besides the existence of the Chemotherapy Concession (profit motive in drug selection) being one of the major factors working against the individualization of cancer chemotherapy based on testing the cancer biology, the NCI had made a feeble attempt years ago, to study assay-directed therapy of lung cancer on its own.

1. Their expertise was in establishing permanent cell lines and they only tested tumors after first culturing them to amplify their cell number (these were all passaged, grown up, multiplied, replated). The result was that their assay evaluability rate for primary lung cancers was only 11%.

2. The second problem they had is that they were selecting subpopulations. Subsequent work showed that you get different results when you test passaged cells compared to primary, fresh tumors.

3. The third problem is that the ability to get lung cancer to actually grow is an independent marker for virulent disease. It was actually the single greatest negative predictor for survival in one study.

So the NCI concluded that it was too much trouble and not all that useful. If they couldn't get it to work at the NCI, then of course no one can do it. That was the attitude thereafter.

"If the NCI can't do something, nobody can." What a heck of a way to do science!

Medicare Coverage for Cell Culture Assay Tests

by Gdpawel on Fri Jul 06, 2007 12:00 AM

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Medicare Contractor Establishes Reimbursement Coverage Policy for Cell Culture Assay Tests
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National Heritage Insurance Company (NHIC), the contractor that administers Medicare programs in California, has established a positive coverage policy for Cell Culture Assay Tests known as Chemosensitivity (Resistance) Testing for a tumor specimen from a Medicare patient obtained anywhere within the United States, but submitted for testing by one of the approved laboratories located within California. Medicare bills for Chemosensitivity (Resistance) Testing are billed through NHIC because the test is conducted by the approved laboratories in California.
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The Chemosensitivity (Resistance) Test can help see what treatments have the best opportunity of being successful for "high" risk cancer patients. The test measures the response of "live" tumor cells to drug exposure. Following this exposure, the assays measure both cell metabolism and cell morphology (Functional Profiling). The integrated effect of the drugs on the whole cell, resulting in a cellular response to the drug, measuring the interaction of the entire genome. Assays based on "cell-death" occur in the entire population of tumor cells.
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This cell culture assay technology has been clinically validated for the selection of optimal chemotherapy regimens for individual patients. It is a laboratory analysis based on tumor tissue profiling that uses "fresh" human tumor biopsy or surgical specimen to determine which drugs or combinations of chemotherapeutic agents have the highest likelihood of response for individual cancer patients.
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Following the collection of "fresh" tumor cells obtained from surgery or tru-cut needle biopsies, a cell culture assay is performed on the tumor sample to measure drug activity (sensitivity and resistance). This will pinpoint which drug(s) are most effective. Tissue, blood, bone marrow, and ascites and pleural effusions are possibilities, providing tumor cells are present. At least one gram of fresh tissue is needed to perform the tests, and a special kit is obtained in advance from the lab.The treatment program developed through this approach is known as assay-directed therapy.
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Individualized assay-directed therapy is based on the premise that each patient's cancer cells are unique and therefore will respond differently to a given treatment. This is in stark contrast to standard or empiric therapy, which chemotherapy for a specific patient is based on average population studies from prior clinical trials.
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The decision had been made that the assay is a perfectly appropriate medical service, worthy of coverage on a non-investigational basis. What is of particular significance is that they abandoned the artificial distinction between "resistance" testing and "sensitivity" testing and are providing coverage for the whole FDA-approved kit. Drug "sensitivity" testing is merely a point a little farther along on the very same continuum which "resistance" testing resides.
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Cell cuture assay tests based on "cell-death" have proven very effective in identifying novel treatment combinations for a variety of cancers. The value of cell-death assays is that they can and do accurately predict clinical outcomes and define novel chemotherapeutic synergies. It can help see what treatments will not have the best opportunity of being successful (resistant) and identify drugs that have the best opportunity of being successful (sensitive).
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The current clinical applications of in vitro chemosensitivity testing is ever more important with the influx of new "targeted" therapies. Given the technical and conceptual advantages of "functional profiling" of cell culture assays together with their performance and the modest efficacy for therapy prediction on analysis of genome expression, there is reason for renewed interest in these assays for optimized use of medical treatment of malignant disease.
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The payment provided will be sufficiently realistic that all Medicare patients for whom this testing is indicated will be able to get it with only the routine 20% co-payment, as Medi-gap insurance secondaries are mandated to provide payment for co-pays for Medicare-approved services.
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The coverage became effective for claims for services performed on or after February 19, 2007. The decision is posted at:
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http://www.medicarenhic.com/cal_prov/policies.shtml

http://www.medicarenhic.com/cal_prov/articles/chemoassaytest
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