FDA Approves New Treatment for Medullary Thyroid Cancer
On April 6, the Food and Drug Administration (FDA) approved vandetanib (Zactima) to treat adult patients with unresectable or metastatic medullary thyroid cancer (MTC). This is the first approved drug treatment for MTC.
The efficacy of vandetanib was demonstrated in an ongoing, randomized, international study of 331 patients with late-stage MTC who were treated with vandetanib or placebo. Patients taking vandetanib had a longer period of time without disease progression compared to those receiving the placebo.
Because serious side effects were associated with vandetanib use including, in some cases, an irregular heart rhythm that could lead to death, the drug is being approved with a Risk Evaluation and Mitigation Strategy (REMS). Only physicians and pharmacies certified through the vandetanib REMS program will be able to prescribe or dispense the drug.
Vandetanib is a small molecule inhibitor of several cell-surface receptors such as RET, which is mutated in hereditary forms of MTC. Blocking these receptors inhibits cancer cell proliferation and migration.
“Vandetanib’s approval underscores FDA’s commitment to approving treatments for patients with rare and difficult to treat diseases,” said Dr. Richard Pazdur, director of the FDA’s Office of Oncology Drug Products.
At its April 12 meeting, the FDA’s Oncologic Drugs Advisory Committee voted to recommend approval for everolimus (Afinitor) and sunitinib (Sutent) to treat advanced pancreatic neuroendocrine tumors (PNET). Although the FDA is not required to follow the suggestions of its advisory committees, it typically does.
PNET are a relatively uncommon tumor type, with fewer than 1,000 patients diagnosed yearly in the United States. These tumors tend to have a better prognosis than other pancreatic tumors, but few treatments are available if they recur.
Both everolimus and sunitinib are currently approved as treatments for advanced renal cell carcinoma. Everolimus, an inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway, causes immune suppression and reduces cell proliferation and tumor blood vessel growth. Results from a randomized clinical trial showed that the time to disease progression for patients taking everolimus was more than double that of patients taking a placebo (11 months versus 4.6 months).
The data supporting sunitinib, a small molecule receptor tyrosine kinase inhibitor that blocks cell proliferation and tumor blood vessel formation, were less clear. The randomized clinical trial testing sunitinib against a placebo in patients with advanced PNET was stopped prematurely and showed a smaller benefit than that detected with everolimus.Both drugs are known to have serious side effects, including kidney failure. Sunitinib has also been linked to heart failure.
The FDA announced on April 8 that it is reviewing results from several clinical trials to investigate a potential association between lenalidomide (Revlimid) use by patients with multiple myeloma and an increased risk of developing new cancers.
Lenalidomide, an analog of thalidomide, is thought to promote cancer cell death, stimulate immune cell activity, and prevent the development of tumor-associated blood vessels. The drug is approved to treat myelodysplastic syndromes and can be used in combination with dexamethasone to treat multiple myeloma.
Currently, the FDA does not recommend delaying, modifying, or restricting the use of lenalidomide for patients being treated according to FDA-approved indications. However, health care professionals and patients are encouraged to report adverse events or side effects related to treatment with lenalidomide to the FDA’s MedWatch Safety Information and Adverse Event Reporting Program.
The FDA will communicate any new recommendations once the safety review is completed.