Kinase inhibitor’s approval accelerated by Priority Review, Breakthrough and Orphan Drug Designations.

Hoffman-LaRoche and the FDA disclosed the approval of Zelboraf (vemurafenib), the first treatment for certain patients with Erdheim-Chester Disease ECD), a rare blood cancer. Zelboraf is a kinase inhibitor that blocks certain enzymes that promote cell growth. Zelboraf is indicated to treat patients who have cancer cells with the specific BRAF V600 genetic mutation.

Richard Pazdur, Acting Director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, offered his insight into the approval. “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.” The product, said Pazdur, was first approved in 2011 to treat certain patients with melanoma that harbor the BRAF V600E mutation. “We are now bringing the therapy to patients with a rare cancer with no approved therapies.”

According to the FDA, ECD is a slow-growing blood cancer that originates in bone marrow and causes an increased production of histiocytes, a type of white blood cell. Patients with ECD have very limited life expectancies. “Excess histiocytes can result in tumors infiltrating many organs and tissues throughout the body, including the heart, lungs, brain and others.” The FDA’s statistics show that ECD is estimated to affect 600 to 700 people around the world each year; approximately 54% of patients with ECD have the BRAF V600 mutation.

Zelboraf’s efficacy and safety treating ECD was studied in 22 patients with BRAF-V600 mutation-positive ECD. The trial measured the percentage of people demonstrating an overall response rate involving either a complete or partial reduction in tumor size. In the trial, 11 patients (50 %t) experienced a partial response and 1 patient (4.5 %) experienced a complete response.