Interim Results of a Phase I Study of Lenalidomide (CC-5013) Plus Intraventricular/Intravenous Rituximab for Recurrent/Refractory CNS and Intraocular Lymphoma

BACKGROUND: There is an unmet need for effective therapies for relapsed/refractory primary and secondary central nervous system (CNS) and intraocular lymphomas (IOL), complications that are increasing in frequency among patients age >60. Whole brain irradiation, broadly utilized in the relapsed setting, yields insufficient efficacy and considerable morbidity, particularly in older patients. Implementation of new agents that selectively target survival pathways upregulated in refractory CNS lymphoma would have significant impact. Lenalidomide (CC-5013) has established activity as a single agent in aggressive NHL, particularly in ABC-type DLBCL. We recently demonstrated the activity of lenalidomide, at modest doses, in the treatment of recurrent/refractory intraocular and CNS lymphoma (J. Clin Oncol, 2011). We also provided evidence of cereblon-dependent efficacy of lenalidomide in preclinical models of patient-derived CNS DLBCL (ASH, 2013). These observations are the basis for this first trial of IMiD® immunomodulatory compound therapy in CNS NHL, as monotherapy, and in patients with inadequate responses to lenalidomide, in combination with combined intravenous plus intraventricular rituximab. (NCT01542918).

METHODS: The primary objective of this phase I study is to evaluate the safety and efficacy of lenalidomide at three dose levels (10, 20, and 30mg) in relapsed/refractory CD20+ CNS NHL, with staging evaluations involving brain, CSF and intraocular compartments. Key secondary endpoints include: (1) determination of extent of CSF penetration by lenalidomide; (2) feasibility and activity of combined intraventricular and intravenous rituximab plus lenalidomide in patients with recurrent CNS lymphoma, not responsive to lenalidomide monotherapy; (3) evaluation of the effects of lenalidomide on the tumor microenvironment, including effects on tumor metabolism and immune cell infiltration and phenotypes.

RESULTS: Thus far, seven subjects with relapsed CNS DLBCL (6 PCNSL, 1 SCNSL) have been treated on protocol at UCSF (median age 63, range 46-77). Each had methotrexate-resistant disease and 4 had lymphoma refractory to high-dose chemotherapy. In general, lenalidomide has been well-tolerated in the CNS lymphoma population with one DLT (non-hematologic) noted at the 20 mg dose level: fatigue and memory loss. Clinical benefit has been noted in 3 out of 4 patients with IOL, with 1 PR > 6 months duration and 1 SD > 10 months duration, each to lenalidomide monotherapy. Brain parenchymal responses to lenalidomide monotherapy (20 mg) have been demonstrated at restaging MRI, including 1 CR and 1 PR. There has been 1 CR in the leptomeninges with resolution of B-cell lymphoma in CSF, quantified by serial flow-cytometry. Combined intraventricular (20 mg) plus intravenous infusion of rituximab was well-tolerated in 3/3 patients and, with 10 mg lenalidomide, resulted in 1 PR in highly refractory IOL. Using GC/MS, we demonstrated lenalidomide penetration in ventricular CSF (0.6-7.9 ng/ml) in each of 4 patients, 12-15 hours after dosing at the 20 mg level, but trough lenalidomide concentrations >0.5 ng/ml were detected in only 1 of 3 patients receiving 10 mg lenalidomide. Serial metabolomic profiling revealed that CSF lactate correlated with clinical response to lenalidomide. Finally, we demonstrated that lenalidomide is reproducibly associated with a rapid and reversible effect on peripheral blood macrophage polarization to an M1, iNOS+ phenotype.

CONCLUSIONS: These preliminary results provide evidence that lenalidomide is well-tolerated at 10 and 20 mg dose levels in CNS lymphoma. We demonstrate for the first time lenalidomide penetration in ventricular CSF, with higher trough concentrations detected at 20 mg compared to the 10 mg dose level. Encouraging evidence of lenalidomide efficacy in relapsed CNS DLBCL has been demonstrated in intraocular, CSF and brain compartments. Combined intraventricular and intravenous infusion of rituximab is feasible and represents a novel strategy to the potentiation of immunotherapeutic strategies in brain tumors. Studies are in progress to further elucidate the safety, pharmacokinetics and mechanisms involved in this biological approach to the treatment of refractory CNS lymphomas.

Supported by NCI, Leukemia and Lymphoma Society, UCSF Helen Diller Comprehensive Cancer Center, Celgene and Genentech