Purpose

This phase 2 trial studies ibrutinib to see how well it works in treating patients with systemic (affecting the entire body) mastocytosis that has spread to other parts of the body and usually cannot be cured or controlled with treatment (advanced). Systemic mastocytosis is a disease in which too many mast cells (a type of immune system cell) are found throughout the body. Mast cells give off chemicals such as histamine that can cause flushing (a hot, red face), itching, abdominal cramps, muscle pain, nausea, vomiting, diarrhea, low blood pressure, and shock. Ibrutinib may stop the growth of mast cells by blocking some of the enzymes needed for cell growth.