BTK and cancer: Due to their dual (i.e., direct and indirect) action mechanism illustrated in Figure 7, BTK inhibitors such as zanubrutinib and ibrutinib, which exhibit the highest binding affinity to the different structural and nonstructural proteins of SARS-CoV-2 and BTK, are speculated to be potential candidate drugs against SARS-CoV-2 and for cancer patients infected with SARS-CoV-2.