FDA Approves Zelboraf to Treat Rare Blood Cancer

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Zelboraf (vemurafenib) became the first approved drug to treat Erdheim-Chester disease (ECD).

Richard Pazdur, M.D.

Zelboraf (vemurafenib) was granted approval by the Food and Drug Administration (FDA) to treat patients with Erdheim-Chester disease (ECD). The BRAF inhibitor is the first agent approved to treat this rare blood disorder.

The approval was based on findings from the phase 2 VE-BASKET study, which included 22 patients with the rare, non-Langerhans histiocytic neoplasm. In the trial, patients with ECD treated with Zelboraf had an objective response rate (ORR) of 54.5 percent, which consisted of a partial response for 11 patients and 1 complete response. After 26.6 months of follow-up, the median progression-free survival, duration of response, and overall survival were not yet reached.

Common side effects included joint pain (arthralgia); small, raised bumps (maculo-papular rash); hair loss (alopecia); fatigue; change in the heart’s electrical activity (prolonged QT interval) and skin growths (papilloma).

More severe side effects included the development of new cancers (skin cancer, squamous cell carcinoma or other cancers), growth of tumors in patients with BRAF wild-type melanoma, hypersensitivity reactions (anaphylaxis and DRESS syndrome), severe skin reactions (Stevens-Johnson Syndrome and toxic epidermal necrolysis), heart abnormalities (QT prolongation), liver damage (hepatotoxicity), photosensitivity, severe reactions in the eye (uveitis), immune reactions after receiving radiation treatment (radiation sensitization and radiation recall), kidney failure and thickening of tissue in the hands and feet (Dupuytren’s contracture and plantar fascial fibromatosis).

Women who are pregnant or hoping to be should know that Zelboraf can cause harm to a developing fetus.

“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,” 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, said in a statement. “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.”

ECD originates in the bone marrow and causes an increased production of a type of white blood cell called histiocytes. Having too many histiocytes may cause tumor infiltration into other vital organs, including the heart, lungs and brain. The disease is expected to affect betwen 600 and 700 patients across the globe, according to a press release by the FDA.

“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 statement. “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.”

Advocacy groups also expressed that they were happy with the approval, too.

“The Erdheim-Chester disease community is very encouraged by this first FDA-approved treatment for ECD, bringing new hope to patients and their families," said Kathleen Brewer, president of ECD Global Alliance. "This new treatment option shows that meaningful breakthroughs can occur rapidly when patients, families, research physicians, industry and the FDA work together to help patients.”

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