AZD9291 First Time In Patients Ascending Dose Study

Inclusion Criteria:

* Provision of signed and dated, written informed consent prior to any study specific procedures, sampling and analyses
* Aged at least 18 years. Patients from Japan aged at least 20 years.
* Histological or cytological confirmation diagnosis of Non Small Cell Lung Cancer (NSCLC).
* Radiological documentation of disease progression while on a previous continuous treatment with an EGFR TKI e.g. gefitinib or erlotinib (with the exception of 1st line expansion cohort). In addition other lines of therapy may have been given. All patients must have documented radiological progression on the last treatment administered prior to enrolling in the study.
* Patients (with the exception of 1st line expansion cohort) must fulfil one of the following:

  * Confirmation that the tumour harbours an EGFR mutation known to be associated with EGFR TKI sensitivity (including G719X, exon 19 deletion, L858R, L861Q) OR
  * Must have experienced clinical benefit from EGFR TKI, according to the Jackman criteria (Jackman et al 2010) followed by systemic objective progression (RECIST or WHO) while on continuous treatment with EGFR TKI.
* Previous treatment with a single-agent EGFR TKI (e.g. gefitinib or erlotinib).
* Females should be using adequate contraceptive measures, should not be breast feeding and must have a negative pregnancy test prior to start of dosing or evidence of non-child bearing potential.
* Male patients should be willing to use barrier contraception.
* For 1st Line expansion cohort ONLY, confirmation that the tumour is EGFRm+ve and have had no prior therapy for their advanced disease (for 1st line patients biopsy will be at time of diagnosis of advanced disease).
* For dose expansion and extension cohorts, patients must also have confirmation of tumour T790M mutation status (confirmed positive or negative) from a biopsy sample taken after disease progression on the most recent treatment regimen (irrespective of whether this is EGFR TKI or chemotherapy).

Prior to entry a result from the central analysis of the patient's T790M mutation status must be obtained.

\- World Health Organisation (WHO) performance status 0-1 with no deterioration over the previous 2 weeks and a minimum life expectancy of 12 weeks.

Exclusion Criteria:

* Treatment with an EGFR TKI (erlotinib or gefitinib) within 8 days (approximately 5x half-life) of the first dose of study treatment.
* Any cytotoxic chemotherapy, investigational agents or other anticancer drugs from the treatment of advanced NSCLC from a previous treatment regimen or clinical study within 14 days of the first dose of study treatment.
* AZD9291 in the present study (ie, dosing with AZD9291 previously initiated in this study).
* Any evidence of severe or uncontrolled systemic diseases, including uncontrolled hypertension, active bleeding diatheses, or active infection.
* Past medical history of interstitial lung disease, drug-induced interstitial lung disease, radiation pneumonitis which required steroid treatment, or any evidence of clinically active interstitial lung disease.