Cancer Treatment Today

Lay Summary: The status of chemosensitivity testing.

The issue of chemosensitivity testing is complex and controversial. The recent article by Schrag et al1 criticized the field of chemosensitivity and drug resistance, concluding that these types of in vitro assays are not yet ready for prime time. The panel of authors attempted to present evidence that in vitro drug response assays should not be used clinically. This issue was first addressed by an exhaustive Medicare Coverage Advisory Committee (MCAC) in 1999. A panel of physicians selected by the Department of Health and Human Services reviewed hundreds of articles from the literature and heard two days of testimony by experts in the field in an open hearing. The panel voted unanimously that although chemosensitivity assays should not be covered, drug resistance assays , a variety of testing for resistance to very high chemo concentrations rather than testing for sensitivity, should be paid for. This became a cause celebre with a vigorous debate in the literature and variant opinions offered by professional bodies. The American Society of Clinical Oncology vigorously objected and recommended: ”
The use of chemotherapy sensitivity and resistance assays to select chemotherapeutic agents for individual patients is not recommended outside of the clinical trial setting. Oncologists should make chemotherapy treatment recommendations on the basis of published reports of clinical trials and a patient’s health status and treatment preferences. Because the in vitro analytic strategy has potential importance, participation in clinical trials evaluating these technologies remains a priority.” I believe that the So. California branch of ASCO with Dr. Wiesenthal dissented from this recommendation, see http://weisenthal.org/medicareletter.pdf.

In conclusion, the proposed assay is not supported by the near-total consensus of expert opinion or professional bodies. There are important dissenters, including some physicians and Medicare.

Rationale:

Schrag D, Garewal HS, Burstein HJ, et al: American Society of Clinical Oncology technology assessment: Chemotherapy sensitivity and resistance assays. J Clin Oncol 22 : 3631 -3638, 2004

John P. Fruehauf In Vitro Drug Resistance Versus Chemosensitivity: Two Sides of Different Coins Journal of Clinical Oncology, Vol 23, No 15 (May 20), 2005: pp. 3641-3643

P. Hwu, A. Y. Bedikian, and E. A. Grimm
Challenges of chemosensitivity testing.
Clin. Cancer Res., September 15, 2006; 12(18): 5258 – 5259.

M. Markman Chemosensitivity and Chemoresistance Testing
J. Clin. Oncol., October 10, 2005; 23(29): 7363 – 7364.

R. Nagourney Chemosensitivity and Resistance Assays: A Systematic Review?
J. Clin. Oncol., May 20, 2005; 23(15): 3640 – 3641.

J. P. Fruehauf and D. S. Alberts
In Vitro Drug Resistance Versus Chemosensitivity: Two Sides of Different Coins
J. Clin. Oncol., May 20, 2005; 23(15): 3641 – 3643.

H. S. Wieand
Chemotherapy Sensitivity and Response Assays: Are the ASCO Guidelines for Clinical Trial Design Too Restrictive?
J. Clin. Oncol., May 20, 2005; 23(15): 3643 – 3644.

M. Castro Resisting a Fundamentalist Policy
J. Clin. Oncol., May 20, 2005; 23(15): 3645 – 3646.