To consolidate or not to consolidate: the role of autologous stem cell transplantation in MCL

Abstract An Ara-C-containing intensified induction therapy followed by autologous stem cell transplantation (ASCT) is considered a highly effective treatment strategy in younger mantle cell lymphoma (MCL) patients, inducing long-lasting remissions. However, ASCT is also hampered by acute and delayed toxicity. Thus, alternative first-line treatment strategies without ASCT but including novel agents are under investigation. With the recently published results of the TRIANGLE trial, showing superiority of an ibrutinib-containing immunochemotherapy induction followed by ASCT compared with the standard therapy and, more strikingly, a noninferiority of an ibrutinib-containing regimen without ASCT compared with the standard regimen with ASCT, we consider the addition of ibrutinib to first-line therapy in younger MCL patients as a new standard of care. Whether ASCT, with additional toxicity, still adds benefit to ibrutinib-based treatment in subsets of patients is not yet determined. In addition, it remains unclear how effective Bruton's tyrosine kinase inhibitor (BTKi) therapy will be in the relapsed setting for patients who received BTKi as part of first-line therapy. It also remains unclear whether the TRIANGLE data can be extrapolated to other BTKi, which is particularly relevant considering it is no longer FDA approved for MCL. Until then, individual patient characteristics and preferences, disease biology, and estimation of risk of toxicity needs to be taken into account when deciding about the addition of ASCT to an ibrutinib-containing induction therapy. For patients with TP53 aberrations, ASCT should not be recommended due to potential toxicity and limited efficacy in this high-risk subgroup. Large randomized clinical trials such as ECOG-ACRIN 4151 will help to ultimately clarify the role of ASCT.