Targeted Therapy with Vemurafenib in Brazilian Children with Refractory Langerhans Cell Histiocytosis: Two Case Reports and a Comprehensive Review

Langerhans cell histiocytosis (LCH) is characterized by inflammatory lesions featuring clonal infiltration. The BRAF mutation stands out as the most prevalent. Vemurafenib has emerged as a therapeutic option. The off-label use of VMF persists in Brazil. We will delineate the cases of two Brazilian children suffering from LCH with a positive response to VMF. Case Report I: The patient underwent standard therapy, but bone marrow infiltration persisted. After confirming a BRAF V600E mutation through testing, VMF was initiated, resulting in significant improvements. Case Report II: The patient initiated VMF and showed a positive response. After several months, maintenance therapy was introduced. However, skin lesions recurred upon discontinuation of VMF. She has been on VMF for a total of 31 months, maintaining remission. The cases presented represent the first reported instances of off-label VMF use in Brazil for the treatment of LCH, and both patients have demonstrated excellent responses to the medication.