Dramatic Response with Single-Agent Ibrutinib in Multiply Relapsed Marginal Zone Lymphoma with MYD88L265P 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 MYD88L265P 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 MYD88L265P-mutated refractory MZL supports a biological rationale for its use.