There is an unmet need for effective
biological therapies for relapsed central nervous system (CNS)
lymphoma.
Lenalidomide is active in activated B-cell type
diffuse large B-cell lymphoma and
rituximab is effective in CNS
lymphoma. These observations are the basis for this first trial of an immunomodulatory drug as monotherapy in CNS
lymphoma, and, in patients with inadequate responses to
lenalidomide, with
rituximab. In an independent cohort, we evaluated
lenalidomide maintenance after salvage with high-dose
methotrexate or focal irradiation in relapsed primary CNS
lymphoma (PCNSL). We determined safety, efficacy, and cerebrospinal fluid (CSF) penetration of
lenalidomide at 10-, 15-, and 20-mg dose levels in 14 patients with refractory CD20+ CNS
lymphoma. Nine subjects with relapsed, refractory CNS
lymphoma achieved better than partial response with
lenalidomide monotherapy, 6 maintained response ≥9 months, and 4 maintained response ≥18 months. Median progression-free survival for
lenalidomide/
rituximab was 6 months. In the independent cohort, response duration with
lenalidomide maintenance after complete responses 2 through 5 were significantly longer than response durations after standard
therapy. The CSF/plasma partition coefficient of
lenalidomide was ≥20% at 15- and 20-mg dose levels. Change in CSF
interleukin-10 at 1 month correlated with clinical response and response duration to
lenalidomide. Metabolomic profiling of CSF identified novel
biomarkers, including
lactate, and implicated indoleamine-2,3
dioxygenase activity with CNS
lymphoma progression on
lenalidomide. We conclude that
lenalidomide penetrates ventricular CSF and is active as monotherapy in relapsed CNS
lymphomas. We provide evidence that maintenance
lenalidomide potentiates response duration after salvage in relapsed PCNSL and delays whole brain
radiotherapy (WBRT). This trial was registered at www.clinicaltrials.gov as #NCT01542918.