Memorial Sloan Kettering Cancer Center (MSK) announced today that the US Food and Drug Administration (FDA) has granted a Breakthrough Therapy Designation to cobimetinib in treatment of patients with histiocytic neoplasms (HN) (Erdheim-Chester Disease, Rosai-Dorfman, Langerhans Histiocytosis), who do not harbor the BRAF V600 mutation. Cobimetinib is an oral inhibitor of MEK1 and MEK2 currently approved to treat melanoma. This designation was granted based on data submitted by MSK, in collaboration with Genentech, a member of the Roche Group, from a phase II trial of single-agent cobimetinib for adults with histiocytic disorders (published in Nature in March 2019 by Eli Diamond, MD; Omar Abdel-Wahab, MD; and David Hyman, MD).