Analysis of additional LGS/SB tumors identified mutations predicted to induce extracellular signal-regulated kinase pathway activation in 82% (23 of 28), including two patients with BRAF fusions, one of whom achieved an ongoing complete response to MEK inhibitor-based combination therapy....These findings, coupled with the observation that a subset of patients with recurrent LGS ovarian cancer experienced dramatic and durable responses to MEK inhibitor therapy, support additional clinical studies of MEK inhibitors in this disease.