Vemurafenib, a BRAF inhibitor that has been approved as a treatment for advanced melanomas, is also successful in treating hairy cell leukemia (HCL). The treatment, which can be taken orally, cleared the malignant cells from the patient’s blood and led to a complete clinical recovery in a number of days.

The study was led by the University of Leicester in England and involved treatment of a patient at Leicester Royal Infirmary. The results were published in the New England Journal of Medicine (2014; doi:10.1056/NEJMc1310849).

“A genetic study of the patient’s blood cells allowed us to identify a mutation in the BRAF gene that is commonly found in skin cancers. This knowledge enabled us to combat the cancer cells with vemurafenib, which has had proven success as a BRAF inhibitor in melanomas, and showed similar success for this patient who had exhausted all other treatment options, which is fantastic,” said Salvador Macip, MD, PhD, of the University of Leicester.

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Background information in the publication explained that the BRAF V600E mutation is present in nearly all cases of HCL. This knowledge has led to many patients with HCL being treated with vemurafenib. The particular patient in this study had biallelic BRAF V600E mutations and a high leukemic burden, so the effects of vemurafenib were able to be studied in vivo.

Macip explained, “What was most surprising was that the drug did not work in the way we expected it to. Whilst it successfully blocked BRAF and killed the cancerous cells, there was no ability to block the downstream cascade of signals. Therefore, more research is required to better understand how this drug works to ensure we are able to use it in the best possible way. This is one of the first clinical examples of this treatment for HCL and we are the first researchers to do a biochemical study of the samples and discover that the drug does not do what it’s supposed to be doing.”

This approach to targeting cancer is an example of precision medicine with clinicians and research scientists working side-by-side to ensure the best treatment—tailored to the individual patient—was provided. This research shows that drugs currently used to target certain cancers could be applied in other malignancies that share similar genetic backgrounds.