Pirtobrutinib, a Highly Selective, Non-Covalent (Reversible) BTK Inhibitor in Relapsed / Refractory Marginal Zone Lymphoma: Results from Phase 1/2 BRUIN Study

Background: Marginal zone lymphoma (MZL) is an indolent lymphoma that is typically treated with chemoimmunotherapy, but often requires sequential therapy. Covalent (c) Bruton tyrosine kinase inhibitors (BTKi) are increasingly being used in the relapsed or refractory (R/R) setting, but options for pts with MZL after cBTKi therapy may be limited. Pirtobrutinib, a highly selective, non-covalent (reversible) BTKi has favorable once daily oral pharmacology that enables continuous BTK inhibition throughout the dosing interval, regardless of intrinsic rate of BTK turnover. Pirtobrutinib has demonstrated promising efficacy and tolerability in pts with poor-prognosis B-cell malignancies following prior therapy, including prior cBTKi. Pirtobrutinib is approved in the USA to treat R/R mantle cell lymphoma after at least two lines of systemic therapy including prior BTKi treatment. Here we report the safety and efficacy of pirtobrutinib in pts with MZL from the BRUIN study (NCT03740529).