A randomized, double-blind study shows oral lenvatinib halts the progression of advanced thyroid cancer for one year and a half, more than the four months of progression-free survival in patients who were given a placebo.
Japanese pharmaceutical firm Eisai commissioned researchers at the University of Texas MD Anderson Cancer Center to conduct an international study on 392 patients from 21 countries, all of whom have become resistant to radioactive iodine treatment. The patients were randomized into groups in a 2:1 ratio, with 261 receiving lenvatinib while the remaining 161 receiving a placebo.
The results show patients who were given lenvatinib had a median progression-free survival rate of 18.3 months, which means the cancer did not become worse for that duration. Meanwhile, those who received a placebo displayed a median progression-free survival rate of 3.6 months.
The researchers also report that 65 percent of the patients in the study arm responded fully or partially to the medication, which Eisai consultant and principal researcher Dr. Steven Sherman believes are "almost unprecedented results" for advanced thyroid cancer patients.
"We also found a strongly suggestive trend in how long patients lived, and a small number of patients had a complete response," said Dr. Sherman. "While we couldn't identify tumor mutations that might predict response, this represents a very exciting area of study going forward in hopes of possibly offering cure to a greater number of patients."
There were no overall survival rates for the study, which has 26 months of follow-up. After 18 months, the last point at which survival was measured, 72.3 percent of the lenvatinib group were still alive, compared to the 63 percent in the placebo group.
However, the drug is not without adverse side effects. The researchers say 97 percent of all patients who were given lenvatinib showed a variety of side effects. More than two-thirds experienced hypertension, with nearly 42 percent of them having lenvatinib-related severe hypertension. Nearly 60 percent also experienced asthma and fatigue, while half had decreased appetites. A little more than half also experienced weight loss and nausea.
The six out of 20 deaths that occurred in the lenvatinib group were determined by their treating physicians to have been caused by the adverse effects of the medication. One case was specifically due to pulmonary embolism; another due to hemorrhage stroke; and another due to deteriorating health. The other three were unspecified.
However, Dr. Sherman says the side effects can be managed by adjusting the dosage of lenvatinib or employing individual measures to keep the side effects at a minimum while maintaining the effectiveness of the drug.
"The side effect profile is actually quite typical for this class of drugs," he said. "We've learned over the years to be aggressive about dosing modifications and coming up with clever ways of helping patients tolerate the medication where drug effectiveness is maintained but with a minimum of those side effects."
The results of the study are detailed in the New England Journal of Medicine.
