BTK and mantle cell lymphoma: Although targeted drugs such as Bruton’s tyrosine kinase (BTK) inhibitor [4, 5], phosphoinositide 3-kinase (PI3K) inhibitors [6, 7], B cell lymphoma-2 (BCL2) inhibitors [8–10] and Poly ADP-ribose polymerase (PARP) inhibitors [11] are developed for the treatment of relapsed/refractory MCL, the prognosis of MCL patients still remains poor.