Orelabrutinib potently inhibits BTK enzymatic activity with an IC50 value of 1.6 nM. In KINOMEscan assay conducted in parallel at 1 μM against a panel of 456 kinases, orelabrutinib only targets BTK with > 90% inhibition while ibrutinib inhibits additional many other kinases including EGFR, TEC and BMX, demonstrating orelabrutinib's superior kinase selectivity.