Abstract
Little is known about outcomes following interruption of targeted therapy in adult patients with histiocytic neoplasms. This is an IRB-approved study of patients with histiocytic neoplasms whose BRAF and MEK inhibitors were interrupted after achieving complete or partial response by 18-fluorodeoxyglucose positron emission tomography (FDG-PET). 17/22 (77%) of patients experienced disease relapse following treatment interruption. Achieving a complete response prior to interruption, having a mutation other than BRAFV600E, and receiving MEK inhibition only were each associated with a statistically significant improvement in relapse-free survival. Relapse is common following treatment interruption however some patients may be suitable for limited-duration treatment.