Treatment holidays in patients with Erdheim-Chester disease receiving vemurafenib: a prospective pilot study

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis driven by mutations of MAPK pathway genes (e.g., BRAF, MAP2K1). Its clinical spectrum ranges from organlimited to diffuse, life-threatening forms. The prognosis of ECD was considered to be poor, but recent targeted treatments (i.e., MAPK inhibitors, such as BRAF-inhibitors, BRAFi, and MEK-inhibitors, MEKi) greatly improved patients’ outcomes. Effective strategies to mitigate toxicity while maintaining disease control are needed. We provide preliminary evidence that a treatment holiday protocol can reduce vemurafenib-associated toxicity and overall drug exposure.