New Drug May Slow Recurrent Thyroid Cancer, Study Finds

By Dennis Thompson

HealthDay Reporter

THURSDAY, Feb. 12, 2015 (HealthDay News) -- A new thyroid cancer drug can delay the progression of the disease almost five times longer than a placebo in people with recurring cancer, according to results from a new clinical trial.

The oral drug, lenvatinib, is a targeted therapy that fights cancer by deterring the growth of new blood vessels that could help feed the cancer, researchers said.

Lenvatinib delayed progression of advanced thyroid cancer by 18 months, compared with four months for patients treated with a placebo, the trial found.

"It's an encouraging time for the advancement of treating patients with many different kinds of cancer," said Dr. Gregory Masters, of the new targeted therapies. Masters is an oncologist at Christiana Care Health System in Newark, Del., and a member of the American Society of Clinical Oncology.

"We're achieving a greater understanding of the pathways by which these cancers grow, and we're using that understanding to block those pathways," said Masters, who was not part of the study.

Results of the study, which was funded by drug manufacturer Eisai, were published in the Feb. 12 issue of the New England Journal of Medicine.

Historically, radioactive iodine has been the only treatment available to people with advanced thyroid cancer, said study leader Dr. Steven Sherman. He is associate vice provost for clinical research, and professor and chair of Endocrine Neoplasia and Hormonal Disorders at the University of Texas MD Anderson Cancer Center in Houston.

Unfortunately, more than half of patients do not respond to radioactive iodine treatment, Sherman said in a center news release. In addition, thyroid cancers tend to develop resistance to radioactive iodine over time, making the therapy less and less effective.

"It's been a disease where it's been very difficult to treat once it's become resistant to radioactive iodine," Masters said.

Lenvatinib must await U.S. Food and Drug Administration approval for use against thyroid cancer, Masters said. Another targeted drug, sorafenib, which works by encouraging the early death of cancer cells, was approved by the FDA in 2013 to treat thyroid cancer.

The international clinical trial for lenvatinib enrolled almost 400 patients from 21 countries, all of whom had thyroid cancer that had spread and become resistant to radioactive iodine.

Researchers treated 261 patients with lenvatinib, while 131 received a placebo. When their cancer started to progress again, patients in the placebo group could receive lenvatinib.

In addition to the nearly fivefold improvement in progression-free survival, the drug also appeared to be useful for treating more patients. About two-thirds of the patients given lenvatinib responded either fully or partially to the drug.

"In our study, we not only saw a dramatic improvement in progression-free survival, there was also a 65 percent response rate -- almost unprecedented results for thyroid cancer patients with such advanced disease," Sherman said.

The clinical trial did not observe any improvement in overall survival due to lenvatinib. However, Masters believes that the drug can't help but improve patients' overall survival, given its effectiveness in halting the cancer's progression.

"Almost for sure, significant improvement like this in disease-free survival ultimately will translate into overall survival," he said. "Sometimes you don't see an improvement in overall survival because patients haven't been followed long enough."

Lenvatinib does come with some serious side effects, however. More than 40 percent of patients that received lenvatinib experienced some type of reaction while on the medication.

High blood pressure was the most common side effect, occurring in two out of three patients who had a reaction to the drug. Other side effects included diarrhea, fatigue, nausea, and decreased appetite and weight.

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