Thyroid cancer is considered highly curable, but for up to 15 percent of patients, the standard treatments of surgery and radioactive iodine (RAI) therapy aren’t enough to keep the disease from progressing. Before the Food and Drug Administration (FDA) approved Nexavar (sorafenib) for treatment-resistant tumors in 2013, the only option for patients whose disease had metastasized was doxorubicin, which later proved to be ineffective and highly toxic. At ASCO’s annual meeting, researchers announced results of a phase 3 trial that could provide a second treatment option: the oral kinase inhibitor lenvatinib. In February, the FDA granted lenvatinib its orphan drug designation, an incentive for pharmaceutical companies to develop treatments for rare diseases (not to be confused with FDA approval, which is only granted after research and clinical trials prove the drug is safe and effective).
Of the 60,000 thyroid cases diagnosed annually, more women than men get the disease, with most patients between the ages of 25 and 65. This study involved 392 participants whose disease had progressed within 13 months of previous treatment. Participants had a median age of 63, and 51 percent were men. Researcher Martin Schlumberger, professor of oncology at the University Paris Sud in Paris, France, said the participants were randomly assigned to receive lenvatinib or a placebo, and participants taking the placebo were allowed to cross over to the lenvatinib arm if their disease worsened.
In announcing the results, Schlumberger said 65 percent of participants who took lenvatinib experienced tumor reduction, compared with 2 percent who took the placebo. Moreover, the time to disease progression was more than 18 months for participants on the lenvatinib arm, compared with almost four months for those on the placebo. However, 97 percent of participants who took lenvatinib experienced some adverse events, primarily high blood pressure, diarrhea, decreased appetite, fatigue and nausea; 14 percent of participants had to stop taking the drug; and although four participants experienced a complete response (meaning they had no evidence of cancer), six participants died from treatment-related causes.
Gregory Masters, an oncologist at the Helen F. Graham Cancer Center in Wilmington, Del., and a member of ASCO’s communications committee who moderated the press briefing, said treating cancer patients with toxic therapies carries risks, but that patients and doctors have to balance the risk of treatment against the benefit of delaying or avoiding treatment.