The EGFR inhibitor, osimertinib, is metabolized and broken down into two pharmacologically active metabolites (AZ7550 and AZ5104), which circulate at around 10% of the concentration of the parent compound (Table 3). One metabolite, AZ5104, which is more potent than osimertinib, downregulates Th17-related cytokine production via inhibition of SRC-ERK-STAT3 (127) (Table 2).