Mantle Cell Lymphoma: First-line Therapy in Patients Not Eligible for Stem Cell Transplantation

Mantle cell lymphoma is a distinct subtype of non-Hodgkin's lymphoma, which has historically been associated with a poor prognosis. It is now recognized as a heterogeneous disease with variable biologic and clinical behavior. Treatment paradigms have evolved along two lines. Younger, fit mantle cell lymphoma (MCL) patients are generally treated with intensive strategies and older less fit patients with non-intensive strategies. Most of the published literature has focused on intensive strategies, which appear to result in more durable remissions, but with an unclear impact on overall survival. The literature is more sparse for the roughly 50% of patients who are not candidates for intensive strategies, and no "standard" approach has been established for this patient population. However, clues are emerging. Randomized clinical trials have (a) established that bendamustine-rituximab (BR) is more efficacious and less toxic than rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP); (b) established that bortezomib should replace vincristine if using an R-CHOP backbone; and (c) established that maintenance rituximab (MR) is beneficial after an R-CHOP induction. In our opinion, it is reasonable to extrapolate the data supporting MR after R-CHOP and apply MR after a BR induction. In our practice, we recommend BR followed by MR for 2 years to MCL patients not eligible for intensive therapy. An ongoing US intergroup trial is testing the addition of bortezomib to the BR backbone and the addition of lenalidomide to MR. This trial may establish a standard of care in the older MCL population. In addition, exciting options for relapsed MCL have emerged in the last few years, with the introduction of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib and the development of the lenalidomide-rituximab combination. In this article, we will discuss the current available options for these older MCL patients and the evidence supporting those options.