FDA Grants Approval to Zelboraf for Certain Patients with Rare Blood Disease

Mathew Shanley

In August, the U.S. Food and Drug Administration accepted Genentech’s supplemental New Drug Application (sNDA) and granted Priority Review to Zelboraf (vemurafenib) for the treatment of Erdheim-Chester Disease (ECD). Today, it was announced that the drug received expanded approval for the drug to include the treatment of adult patients whose cancer cells have the BRAF V600 mutation.

ECD is characterized by the absence of Langerhans cells, or antigen-presenting immune cells of the skin and mucosa, and the abnormal multiplication of white blood cells known as histiocytes, making the condition a rare non-Langerhans cell histiocytosis. Symptoms in patients with ECD commonly include moderate, lingering bone pain in the lower limbs and failure of the kidneys and liver.

Fewer than 500 cases of ECD have been reported in the United States, however, more than 50% of people with the condition are BRAF V600 mutation-positive. Zelboraf, a prescription medication typically used to treat melanoma, is intended to inhibit mutated forms of BRAF.

"Today's approval of Zelboraf for patients with ECD demonstrates how we can apply knowledge of the underlying genetic characteristics of certain malignancies to other cancers," said Richard Pazdur, M.D., director of the FDA's Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research in a press release. "This product was first approved in 2011 to treat certain patients with melanoma that harbor the BRAF V600E mutation, and we are now bringing the therapy to patients with a rare cancer with no approved therapies."

Today’s approval of Zelboraf marks the first FDA-approved treatment for ECD, however, as Pazdur mentioned, this is the second rare cancer for which the drug has been approved. 

The drug operates as a kinase inhibitor, blocking specific enzymes that promote cell growth. It was studied in 22 patients with BRAF-V600-mutation positive ECD in the VE-BASKET Study, and was deemed efficient after the trial exhibited that 50% of patients (n=11) experienced a partial response, ad 4.5% of patients (n=1) experienced a complete response.

The most severe adverse events (AEs) of patients treated with Zelboraf included the development of new cancers, including skin cancer, squamous cell carcinoma or other cancers. Additionally, growth of tumors in patients with BRAF wild-type melanoma, hypersensitivity reactions, severe skin reactions, heart abnormalities, liver damage, and photosensitivity were experienced.

Common side effects experienced by patients treated with the drug included joint pain, raised bumps, hair loss, fatigue, change in the heart’s electrical activity, and skin growths.

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