Osimertinib in First and Second Line Treatment of NSCLC Harboring EGFR Mutations From Circulating Tumor DNA

Inclusion Criteria: \< Cohort 1 \> 1. Provision of informed consent prior to any study specific procedures 2. Patients (male/female) must be \> 18 years of age. 3. Locally advanced or metastatic non-small cell lung cancer, not amenable to curative surgery or radiotherapy with or without pathologic diagnosis 4. No prior exposure to EGFR TKI (multiple lines of prior cytotoxic chemotherapy are permitted.) 5. Activating EGFR mutation (G719X, exon 19 deletion, L858R, L861Q) detected from circulating tumor DNA either by PANA mutyper® or Cobas® EGFR mutation test. 6. Activating EGFR mutation (G719X, exon 19 deletion, L858R, L861Q) detected from tumor tissue or cytology specimen. 7. World Health Organization (WHO) performance status 0-2. 8. Patients must have a life expectancy ≥ 12 weeks. 9. Females should be using adequate contraceptive measures, should not be breast feeding and must have a negative pregnancy test prior to start of dosing if of child-bearing potential or must have evidence of non-child-bearing potential by fulfilling one of the following criteria at screening: * Post-menopausal defined as aged more than 50 years and amenorrheic for at least 12 months following cessation of all exogenous hormonal treatments * Women under 50 years old would be consider postmenopausal if they have been amenorrheic for 12 months or more following cessation of exogenous hormonal treatments and with luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels in the post-menopausal range for the institution * Documentation of irreversible surgical sterilisation by hysterectomy, bilateral oophorectomy or bilateral salpingectomy but not tubal ligation 10. Male patients should be willing to use barrier contraception. 11. Patient is willing and able to comply with the protocol for the duration of the study including undergoing treatment and scheduled visits and examinations including follow up. 12. At least one lesion, not previously irradiated, that can be accurately measured at baseline as ≥ 10 mm in the longest diameter (except lymph nodes which must have short axis ≥ 15 mm) with computed tomography (CT) \< Cohort 2 \> 1. Provision of informed consent prior to any study specific procedures 2. Patients (male/female) must be \> 18 years of age. 3. Locally advanced or metastatic non-small cell lung cancer, not amenable to curative surgery or radiotherapy with or without pathologic diagnosis 4. Progression after prior exposure to gefitinib, erlotinib, afatinib or dacomitinib. Multiple lines of prior cytotoxic chemotherapy are permitted and there is no specified order of treatment. 5. Patients must fulfil one of the following: 5.1) Activating EGFR mutation (G719X, exon 19 deletion, L858R, L861Q) from tumor tissue or cytology or circulating tumor DNA 5.2) Must have experienced clinical benefit from prior EGFR-TKI, according to the Jackman criteria (Jackman 2010) followed by systemic objective progression (RECIST) while on continuous treatment with EGFR-TKI 6. T790M mutation detected from circulating tumor DNA either by PANA mutyper® or Cobas® EGFR mutation test. 7. World Health Organization (WHO) performance status 0-2. 8. Patients must have a life expectancy ≥ 12 weeks. 9. Females should be using adequate contraceptive measures, should not be breast feeding and must have a negative pregnancy test prior to start of dosing if of child-bearing potential or must have evidence of non-child-bearing potential by fulfilling one of the following criteria at screening: * Post-menopausal defined as aged more than 50 years and amenorrheic for at least 12 months following cessation of all exogenous hormonal treatments * Women under 50 years old would be consider postmenopausal if they have been amenorrheic for 12 months or more following cessation of exogenous hormonal treatments and with LH and FSH levels in the post-menopausal range for the institution * Documentation of irreversible surgical sterilisation by hysterectomy, bilateral oophorectomy or bilateral salpingectomy but not tubal ligation 10. Male patients should be willing to use barrier contraception. 11. Patient is willing and able to comply with the protocol for the duration of the study including undergoing treatment and scheduled visits and examinations including follow up. 12. At least one lesion, not previously irradiated, that can be accurately measured at baseline as ≥ 10 mm in the longest diameter (except lymph nodes which must have short axis ≥ 15 mm) with computed tomography (CT) Exclusion Criteria: 1. Previous treatment with AZD9291, or other 3rd generation EGFR TKI 2. Treatment with an investigational drug within five half-lives of the compound 3. Patients currently receiving (or unable to stop use prior to receiving the first dose of study treatment) medications or herbal supplements known to be potent inhibitors of CYP3A4 (at least 1 week prior) and potent inducers of CYP3A4 (at least 3 week prior) (Appendix A). All patients must try to avoid concomitant use of any medications, herbal supplements and/or ingestion of foods with known inducer/inhibitory effects on CYP3A4. 4. Any unresolved toxicities from prior therapy greater than Common Terminology Criteria for Adverse Events (CTCAE) grade 1 at the time of starting study treatment with the exception of alopecia and grade 2, prior platinum-therapy related neuropathy. 5. Any evidence of severe or uncontrolled systemic diseases, including uncontrolled hypertension and active bleeding diatheses, which in the investigator's opinion makes it undesirable for the patient to participate in the trial or which would jeopardise compliance with the protocol, or active infection including hepatitis B, hepatitis C and human immunodeficiency virus (HIV). Screening for chronic conditions is not required. 6. Patients with symptomatic central nervous system (CNS) metastases who are neurologically unstable 7. Past medical history of interstitial lung disease (ILD), drug-induced ILD, radiation pneumonitis requiring steroid treatment, or any evidence of clinically active ILD 8. Inadequate bone marrow reserve or organ function as demonstrated by any of the following laboratory values: Absolute neutrophil count \<1.5 x 109/L Platelet count \<100 x 109/L Haemoglobin \<90 g/L Alanine aminotransferase \>2.5 times the upper limit of normal (ULN) if no demonstrable liver metastases or \>5 times ULN in the presence of liver metastases Aspartate aminotransferase \>2.5 times ULN if no demonstrable liver metastases or \>5 times ULN in the presence of liver metastases Total bilirubin \>1.5 times ULN if no liver metastases or \>3 times ULN in the presence of documented Gilbert's Syndrome (unconjugated hyperbilirubinaemia) or liver metastases Creatinine \>1.5 times ULN concurrent with creatinine clearance \<50 ml/min (measured or calculated by Cockcroft and Gault equation); confirmation of creatinine clearance is only required when creatinine is \>1.5 times ULN. 9. Any of the following cardiac criteria: 1. Mean resting corrected QT interval (QTc using Fredericia's formula) \> 470 msec 2. Any clinically important abnormalities in rhythm, conduction or morphology of resting ECG (e.g., complete left bundle branch block, third degree heart block, second degree heart block) 3. Any factors that increase the risk of QTc prolongation or risk of arrhythmic events such as heart failure, hypokalemia, congenital long QT syndrome, family history of long QT syndrome or unexplained sudden death under 40 years of age in first degree relatives or any concomitant medication known to prolong the QT interval 10. Refractory nausea and vomiting, chronic gastrointestinal diseases, inability to swallow the formulated product or previous significant bowel resection that would preclude adequate absorption of AZD9291 11. History of hypersensitivity to AZD9291 (or drugs with a similar chemical structure or class to AZD9291) or any excipients of these agents 12. Males and females of reproductive potential who are not using an effective method of birth control and females who are pregnant or breastfeeding or have a positive (urine or serum) pregnancy test prior to study entry 13. Judgment by the Investigator that the patient should not participate in the study if the patient is unlikely to comply with study procedures, restrictions and requirements 14. Previous allogeneic bone marrow transplant. 15. Non-leukocyte depleted whole blood transfusion within 120 days of the date of the genetic sample collection.