The US Food and Drug Administration has approved the radiotherapy drug Azedra (iobenguane I-131) to treat some adults and adolescents ages 12 and older with rare tumors of the adrenal gland called pheochromocytomas, as well as for similar tumors outside of the adrenals, called paragangliomas. The new drug approval is for tumors that have spread and cannot be removed through surgery.
Pheochromocytomas are rare tumors of the adrenal glands. These glands are located right above the kidneys and make certain hormones, including stress hormones such as adrenaline. The tumors increase production of these hormones, leading to high blood pressure and symptoms such as headaches, irritability, sweating, rapid heart rate, nausea, vomiting, weight loss, weakness, chest pain or anxiety. When this type of tumor occurs outside the adrenal gland, it is called a paraganglioma.
Most often these types of tumors are not cancer, even though they can still cause serious symptoms. But a small number of these tumors are malignant, meaning that they can spread to other parts of the body. Surgery to remove the tumor is the most common treatment if it can be done, although other types of treatment might be used as well.
The FDA based its approval of Azedra on a clinical trial of 68 people. The goal of the study was to measure the number of people who were able to cut their blood pressure medicine in half and maintain that for at least 6 months. Participants also underwent scans to measure the size of their tumors. Seventeen patients (25%) cut their blood pressure medication by at least half, and 15 (22%) had their tumors shrink.
The FDA evaluated Azedra through its fast track, breakthrough therapy, and priority review programs, which are meant to speed up the availability of drugs to treat serious diseases. Azedra also received orphan product designation, which provides incentives to developers for drugs intended to treat a rare disease.
Azedra is given intravenously (as an IV). The most common severe side effects include low blood counts, increased risk of bleeding, fatigue, nausea, vomiting, dizziness, and high blood pressure.
Azedra also comes with several warnings, including a risk of radiation exposure from the drug. The risk is greater in adolescent patients. People should limit their contact with others while getting the drug. Radiation exposure associated with Azedra may cause infertility in men and women.
Other warnings and precautions include a risk of lower levels of blood cells, underactive thyroid, increase in blood pressure, kidney problems, and inflammation in the lungs. Some leukemias were observed in patients who received Azedra. Women should not take the drug while pregnant because it can cause harm to a developing fetus.
Azedra is marketed by Progenics Pharmaceuticals, Inc.
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