Dramatic Response with Single-Agent Ibrutinib in Multiply Relapsed Marginal Zone Lymphoma with MYD88^L265P Mutation

The B-cell receptor signaling pathway is important in the lymphomagenesis of many lymphomas, including marginal zone lymphoma (MZL). Herein we describe a case of extranodal MZL refractory to multiple lines of therapy. The presence of an IgM paraprotein prompted further evaluation, and the patient was found to have an MYD88^L265P mutation. Treatment with ibrutinib led to a dramatic response with prompt resolution of symptoms and significant improvement in measurable sites of disease. The excellent response to ibrutinib in our patient with MYD88^L265P-mutated refractory MZL supports a biological rationale for its use.