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Lenalidomide monotherapy as salvage treatment for recurrent primary CNS lymphoma

The prognosis of patients with primary CNS lymphoma (PCNSL) who fail high-dose methotrexate (HD-MTX)–based chemotherapy remains poor, particularly in older individuals, and improvements in salvage chemotherapy are needed. The few cytotoxic agents available for this condition demonstrate limited efficacy.1 Lenalidomide is an immunomodulatory agent, derived from thalidomide, with antiproliferative activities that might act by modifying the tumor microenvironment and activating cytotoxic T and natural killer cells.2 Its efficacy has been established in multiple myeloma and more recently as a single agent or in combination with rituximab in several types of non-Hodgkin lymphomas. In refractory or relapsed systemic diffuse large B-cell (DLBC) lymphomas, lenalidomide exhibited a 28%–35% response rate with a good safety profile.3,4 Interestingly, pomalidomide, a lenalidomide analog, showed activity against CNS lymphoma in murine models and is currently investigated in a phase I study (NCT 01722305). Although little is known about the capacity of lenalidomide to cross the blood–brain barrier,5 this drug appears to be potentially active in PCNSL. The objective of this retrospective case series was to determine the response rate to a standard dose of lenalidomide.