Additionally, other sites within BTK such as T474 and L528 are rarely (if ever) mutated in Ibrutinib and Acalabrutinib-treated CLL patients (Figure 1d, Supplementary file 1, Maddocks et al., 2015; Woyach et al., 2014; Blombery et al., 2022; Woyach et al., 2017; Kanagal-Shamanna et al., 2019; Sharma et al., 2016). Here, BTK is linked to B-cell chronic lymphocytic leukemia.