Clinical experience with lenalidomide alone or in combination with rituximab in indolent B-cell and mantle cell lymphomas.

Lenalidomide is an oral immunomodulatory drug with significant activity in indolent B-cell and mantle cell lymphomas. Lenalidomide has a manageable safety profile whether administered as a single agent or in combination with rituximab. The combination of lenalidomide with rituximab, known as the 'R(2)' regimen, enhances efficacy over what has been shown with monotherapy and has demonstrated activity in patients considered resistant to rituximab. Tolerability of these regimens has been consistent among studies. Asymptomatic neutropenia is the most common grade 3/4 adverse event, typically managed by dose interruption, followed by dose reduction once neutrophils have recovered. Nonhematologic toxicities (e.g. fatigue) are generally low-grade, manageable with concomitant treatment, and/or lenalidomide dose modification. More frequent with R(2), immune-related symptoms such as rash and tumor flare are important to recognize as lenalidomide-associated treatment effects in patients with lymphoma who require supportive care and potential dose modifications. Severe tumor flare reactions with painful lymphadenopathy are not typically observed outside of chronic lymphocytic leukemia/small lymphocytic lymphoma. Venous thromboembolism is uncommon in lymphomas, though prophylaxis is recommended. The general safety profile, differences between lenalidomide monotherapy and R(2) treatment, and optimal strategies for managing adverse events are discussed here.