HLX208 is another, more recent, novel RAF monomer-selective inhibitor that has shown promising efficacy and a well-tolerated safety profile in BRAFV600E-mutant adult patients with Langerhans cell histiocytosis (LCH) and/or Erdheim–Chester disease (ECD) [138,139]. This evidence concerns the gene RAF1 and Langerhans cell histiocytosis.