ABCB1 and central nervous system disorder: Osimertinib is metabolized by the drug-metabolizing enzymes cytochrome P450 (CYP) 3A4 and CYP3A5 [9], and it is a substrate of ATP-binding cassette (ABC) transporters, including P-glycoprotein encoded by ABCB1 and BCRP encoded by ABCG2. The mean osimertinib C0 is significantly lower in patients with the T/T genotype of ABCB1 3435 C > T than in those with the C allele, and ABCB1 3435 C > T and AGCG2 34G > A are risk factors for progression of central nervous system diseases [10].