Presently used chemotherapy drugs have a high rate of failure. This was brought out in a January 10, 2002, issue of the New England Journal of Medicine, when it was noted that 20 years of clinical trials using chemotherapy on advanced lung cancer have yielded survival improvement of only 2 months. It also pointed out that while new chemotherapy regimens appear to be improving survival, when these same regimens are tested on a wider range of cancer patients, the results have been disappointing. In other words, oncologists at a single institution may obtain a 40-50% response rate in a tightly controlled study, but when these same chemotherapy drugs are administered in a real world setting, the response rates decline to only 17-27%.
In that case, knowing which chemotherapy agent "will" or "will not" work is essential.
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.
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.
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
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
One interesting note about Dr. Larry Weisenthal (Weisenthal Cancer Group), a male NSCLC (diagnosed stage IIIB or IV) patient availed himself to the Weisenthal Cancer Group for chemosensitivity testing. Tissue specimens that were sent to the lab showed resistance to single agent cisplatin and carboplatin and resistance to taxol. However, the drug combination of gemcitabine + carboplatin + vinorelbine + high dose tamoxifen + gefitinib (Iressa) was very synergistic and tested sensitive.
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. 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 (if at all) and according to his oncologist, certainly would not have ever been treated with the combination that had shown activity in the screen.
His oncologist at the leading cancer center appears to be a firm convert to the benefits of this prescreening.