Chemotherapy Drug Stops Cancer Growth in Advanced Thyroid Cancer Patients

Bortezomib (Velcade) stops cancer growth in patients with advanced differentiated thyroid cancer who do not respond to the standard treatment of surgery and radioactive iodine, according to a recent study presented at the 77th Annual Meeting of the American Thyroid Association (ATA) in Phoenix.

"This is encouraging news for advanced thyroid cancer patients, given that there is currently no effective chemotherapy treatment for people with advanced thyroid cancer who don't respond to radioactive iodine," said Steven I. Sherman, MD, a director on the ATA Executive Council, head of the National Thyroid Cancer Treatment Cooperative Study Group, and chair of endocrinology at the University of Texas M. D. Anderson Cancer Center in Houston.

Proteasome Inhibitors

Bortezomib is the first in a new class of drugs, called proteasome inhibitors, that block the action of proteasomes-cellular complexes that break down proteins—to stop cancer growth. It has been approved in the treatment of multiple myeloma.

Papillary and follicular carcinomas are considered differentiated carcinomas, and patients with these tumors are often treated similarly. Papillary is the most common type of thyroid cancer (70%-80% of thyroid cancers) and can occur at any age. Follicular thyroid cancers (10%-15% of cancers) tend to occur in somewhat older patients than papillary cancer.

Early Results

In the first stage of this multicenter phase II study, 12 patients with advanced differentiated thyroid cancer used bortezomib in 3-week cycles and were evaluated every 6 weeks. Findings show that cancer growth stopped in seven (58%) of these patients after a minimum of four treatment cycles. The first study patient's cancer had steadily progressed for 5 years prior to the treatment, but the cancer has not grown since the patient has been on the drug for more than 1 year.

"This study shows that there are more drugs becoming available that may be able to slow down the progression of cancer, if not shrink the tumors," added Dr. Sherman, who is the principal investigator of this study funded by the National Cancer Institute. "Hopefully we are entering a new era of effective chemotherapy with new biologic agents in thyroid cancer."