<h4>Background</h4>Allogeneic hematopoietic cell transplantation (alloHCT) remains a curative option for relapsed or refractory (r/r) mantle cell lymphoma (MCL), although its role has shifted in the era of Bruton tyrosine kinase inhibition (BTKi) and chimeric antigen receptor T-cell (CAR-T) therapy. Here, BTK is linked to mantle cell lymphoma.