Part A will have a non-randomised, open-label, parallel group, multi-centre design to investigate the pharmacokinetics (PK) of a single dose of osimertinib in patients with severe renal impairment compared with patients with normal renal function. Patients with severe renal impairment will be recruited before those with normal renal function to allow the cohorts to be matched as closely as possible in terms of demographic characteristics (ie, age, body mass index [BMI] and sex).