Sudden Onset of Brain Metastasis despite the Use of Vemurafenib for Another Metastatic Lesion in Malignant Melanoma Patients

Vemurafenib is an inhibitor of the BRAF mutation and has been approved by the Food and Drug Administration as a treatment option for patients with unresectable melanoma without brain metastasis. In the literature, vemurafenib has been reported to be also effective against brain metastasis. We encountered 3 cases with brain metastasis on vemurafenib therapy. In these cases, vemurafenib was clinically effective against metastatic lesions other than those in the brain. The brain lesions developed after the metastatic lesion had occurred. Therefore, we assume that the melanomas of the patients acquired resistance against vemurafenib. The brain metastases were treated with the cyberknife. Patients 1 and 2 without LDH elevation are still alive, but patient 3 with abnormal LDH elevation died despite the treatment. We need to carefully follow patients on vemurafenib therapy because brain metastasis can suddenly occur even if the metastatic lesion has decreased clinically. The therapeutic effect of vemurafenib against brain metastasis is poor in cases with LDH elevation.