Review of Bruton tyrosine kinase inhibitors for the treatment of relapsed or refractory mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare subtype of aggressive B-cell non-Hodgkin lymphoma that remains incurable with standard therapy. Patients typically require multiple lines of therapy, and those with relapsed or refractory (R/R) disease have a very poor prognosis. The Bruton tyrosine kinase (BTK) inhibitor ibrutinib has proven to be an effective agent for patients with R/R MCL. Although usually well tolerated, ibrutinib can be associated with unique toxicities, requiring discontinuation in some patients. Effective and well-tolerated alternatives to ibrutinib for patients with R/R MCL are therefore needed. Novel BTK inhibitors such as acalabrutinib, zanubrutinib, and tirabrutinib are designed to improve on the safety and efficacy of first-generation BTK inhibitors such as ibrutinib. Data from single-arm clinical trials suggest that, compared with ibrutinib, second-generation BTK inhibitors have comparable efficacy and might have a more favourable toxicity profile. Those newer BTK inhibitors might therefore provide a viable treatment option for patients with R/R MCL.