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Chemosensitivity Testing

gdpawel's picture
gdpawel
Posts: 549
Joined: May 2001

Chemosensitivity Testing

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.

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

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/

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

One interesting note about Dr. Larry Weisenthal (Weisenthal Cancer Group). Someone very close to him had advanced ovarian cancer a few years ago. She underwent heroic debulking surgery (from pelvic floor to diaphragm) and tissue specimens were sent for chemosensitivity testing which showed resistance to single agent cisplatin and carboplatin and resistance to taxol. The three drug combination of vinorelbine, gemcitabin and high dose tamoxifen was very synergistic and tested sensitive. She was treated with 6 cycles of gemcitabine, carboplatin, vinorelbine and high dose tamoxifen with only minimal nausea and with no other toxicity. He CA-125 normalized, her bowel symptomatology normalized and she gained back all of the 25 or so pounds which she had lost. She state that she now feels better than she has in years and will undergo a second laparotomy sometime soon. This person "never" would have benefited with taxol/carboplatin.

By complete coincidence, the same week they tested this women's specimen, they tested a non-small cell lung cancer specimen from a pharmaceutical company executive (a doctor). By complete coincidence, the "in vitro best regimen" for this patient was quite similar to the woman, and he was treated with gemcitabine + carboplatin + vinorelbine + high dose tamoxifen + gefitinib (Iressa).

He completed 6 x 3 week cycles incorporating 2 doses per cycle with the exception of carboplatin which was administered only once per cycle. After two cycles, the main mass in his lung had reduced 85% and lymph nodes were virtually undetectable. After 4 cycles, the CT of his lung showed only a small residual mass which was not detected by Pet. A small contrast in the MRI of his brain has remained unchanged throughout his treatment and is now thought to be unrelated to his cancer. He just had his first scan since completing the IV chemotherapy in October 2003 (he continues on Iressa at 250mg/day) and all appears unchanged and is still considered a complete response by his oncologist.

Without the screen, he firmly believes he would have been placed on standard therapy (like taxol/carboplatin) which would not have been nearly as effective (or at all) and certianly would not have ever been treated with the combination that had shown activity in the "screen".

gdpawel's picture
gdpawel
Posts: 549
Joined: May 2001

The clinical utility and clinical accuracy of cell culture drug resistance testing (chemosensitivity testing) with cell-death endpoints has now been proven beyond doubt.

Data on it may be reviewed at http://www.htaj.com/chemosensitivity_and_resistance_testing.wmv (a 27 minute video on .wmv format)

and http://weisenthal.org/faqw.htm

The cost of drugs is enormous. Patients are followed with serial CT scans, MRIs and even Pet Scans, just to see if a tumor is growing or shrinking. Not to mention the hospitalizations for toxicity, bone marrow transfusions, etc. The point is, the cost of ineffective therapy is truly enormous and assay-testing is particulary good at identifying ineffective therapy.

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