PURPOSE : Infectious complications constitute a leading cause of morbidity and mortality in chronic lymphocytic leukemia (CLL). Patients respond poorly to vaccines, particularly pneumococcal polysaccharide and influenza vaccines. Additionally, patients with genetically high risk disease are at increased risk for early disease progression and death. Lenalidomide, an oral immunomodulatory agent with demonstrated clinical activity in CLL, can potentially restore immune system dysfunction associated with CLL while improving disease outcomes.

EXPERIMENTAL DESIGN : Phase 2 study randomized 49 patients with genetically high-risk CLL or SLL (defined as unmutated IGHV, deletion(17p) or (11q), and/or complex abnormal karyotype), to receive lenalidomide either concurrent (Arm A) or sequential to (Arm B) 2 doses of 13-valent protein-conjugated pneumococcal vaccine (PCV13) administered 2 months apart, in patients not meeting IWCLL treatment criteria.

RESULTS : Four serotypes (3, 4, 5, 6B) achieved the additional seroprotection definition of a 4-fold increase in arm A, and 6 serotypes (3, 4, 5, 6B, 19A, 19F) in arm B. All patients achieved the defined concentration of 0.35ug/ml for at least one serotype tested. No significant difference was observed with the addition of lenalidomide. At median time on treatment of 3.6 years, median PFS was 5.8 years (95% CI 3.1-NR). PFS at 1, 2 and 3 year was 85% (95% CI 72-93), 79% (64-88), and 72% (95% CI 57-83) respectively.

CONCLUSION : Lenalidomide is efficacious with manageable toxicities as an early intervention strategy in patients with high-risk CLL, but did not enhance humoral response to PCV13 vaccine. This trial was registered with ClinicalTrials.gov Identifier: NCT01351896.