(RxWiki News) Thyroid cancers are typically (and thankfully) less aggressive than most other cancers but sometimes they cannot be treated using traditional therapy.
Some thyroid cancer patients become resistant to radioactive iodine and may need alternate therapies. The only medication currently approved for these patients is doxorubicin, for which various side effects have been reported.
Sorafenib, brand name Nexavar, is approved by the FDA for treatment of kidney and liver cancers. It is currently being examined for its effectiveness in treating resistant thyroid cancers that have begun to spread to other tissues.
Results of a recent clinical trial have showed that sorafenib kept a certain type of thyroid cancer from getting worse.
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The study was conducted by Marcia Brose, MD, PhD, assistant professor of otolaryngology and head and neck surgery in the Abramson Cancer Center and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia and collaborators from institutions in the US and Europe.
The objective of the clinical trial was to examine the effectiveness and safety of sorafenib in a type of thyroid cancer known as radioactive iodine-refractory differentiated thyroid cancer that does not respond to radioactive iodine, the standard treatment for such cancers.
Differentiated thyroid cancer accounts for about 85 percent of thyroid cancer cases diagnosed in the US each year. This cancer is relatively less aggressive and has high cure rates when treated with radioactive iodine and surgery.
Sorafenib is a protein kinase inhibitor, which means that it blocks enzymes that can cause cells to become cancerous.
This medication has shown promise in early clinical trials for the treatment of radioactive iodine-resistant metastatic thyroid cancers. Metastatic cancers are tumors in which the cancerous cells have spread to neighboring tissues.
The researchers recruited 417 patients with this type of cancer. The patients were randomly assigned to two groups. One group received sorafenib and the other group received a placebo, a blank pill with no therapeutic effects.
Progression-free survival was measured in the patients in both groups. This measure is the length of time during and after treatment that the patient lives with the disease without it worsening.
The median progression-free survival for the patients taking sorafenib was 10.8 months, compared to 5.8 months in the placebo group. The median indicates that one half of the participants had progression-free survival rates above the median and the other half below the median.
Shrinking of the tumor by 30 percent or more was observed in around 12 percent of the patients taking sorafenib and 0.5 percent of the patients in the placebo group.
Overall, according to the study, sorafenib resulted in significantly better progression-free survival rates in patients with radioactive iodine-refractory differentiated thyroid cancer.
“After having no effective drugs for these patients for so many years, it is very exciting to find an oral drug that stops growth of the cancer for several months,” said lead author Dr. Brose. “For these patients, a longer progression-free survival means more months without hospitalization and invasive procedures to control pain and other symptoms. This is the first time we have had a systemic treatment that can help.”
Profession-free survival rates measure the time during and after treatment where the condition does not get worse and may not have an effect on overall survival rates. Overall survival rates look at the number of people alive for a given length of time after diagnosis or treatment. Overall survival rates were not available in this study at this time.
The researchers plan to analyze data from this study in detail to find which patients would respond better to sorafenib and which ones need other treatments. The authors conceded that the disease will likely progress eventually after sorafenib treatment and acknowledged the need to develop additional therapies.
The cost of treatment with sorafenib is around $2,500 for 30 200 mg tablets in the US, which equates to around $83 per tablet.
The results of the study were presented at the American Society of Clinical Oncology annual meeting in June 2013.
The authors disclosed consulting relationships with various companies including Bayer, the maker of sorafenib. The study was funded by Onyx Pharmaceuticals and Bayer.