A Study of 5 Years of Adjuvant Osimertinib in Completely Resected Epidermal Growth Factor Receptor Mutation (EGFRm) Non-small Cell Lung Carcinoma (NSCLC)

Inclusion Criteria:

1. Male or female aged at least 18 years.

2. Histologically confirmed diagnosis of primary NSCLC on predominantly non-squamoushistology.

3. Magnetic Resonance Imaging (MRI) or contrast computed tomography (CT) scan of thebrain.

4. Participants must be classified post-operatively as Stage II, IIIA, or IIIB on thebasis of surgical pathologic criteria.

5. Confirmation by the local laboratory that the tumour harbours one of the two commonEGFR mutations (Ex19del, L858R), either alone or in combination with other EGFRmutations including de novo EGFR mutation resulting in substitution of threoninewith methionine at amino acid position 790 in exon 20 of EGFR (T790M) or uncommonEGFR mutations G719X, S768I, and L861Q, either alone, in combination with eachother, or in combination with other uncommon EGFR mutations (excluding all exon 20insertions) (Uncommon EGFRm Cohort).

6. Complete surgical resection of the primary NSCLC is mandatory. All gross diseasemust have been removed at the end of surgery. All surgical margins of resection mustbe negative for tumour.

7. Complete recovery from surgery and standard post-operative therapy (if applicable)at start of study intervention.

8. World Health Organisation Performance Status of 0 to 1.

9. Female participants must be using highly effective contraceptive measures, and musthave a negative pregnancy test prior to start of dosing if of childbearingpotential.

10. Male participants must use effective barrier contraception.

Exclusion Criteria:

1. Major surgery (including primary tumour surgery, excluding placement of vascularaccess) within 4 weeks prior to the first dose of study drug.

2. Participants currently receiving medications or herbal supplements known to bestrong inducers of CYP3A4 (at least 3 weeks prior to first dose).

3. Participants who have had only segmentectomies or wedge resections.

4. History of other malignancies, except: adequately treated non-melanoma skin cancer,curatively treated in situ cancer, or other solid tumours curatively treated with noevidence of disease for > 5 years before the start of study intervention.

5. Treatment with any of the following:

• Pre-operative or post-operative or planned radiation therapy for the currentlung cancer.

• Pre-operative (neo-adjuvant) platinum-based or other chemotherapy.

• Any prior anti-cancer or immunological therapy, including investigationaltherapy, for treatment of NSCLC other than standard platinum-based doubletpost-operative adjuvant chemotherapy.

• Prior treatment with neoadjuvant or adjuvant EGFR tyrosine kinase inhibitor (TKI).

6. Refractory nausea and vomiting, chronic gastrointestinal diseases, inability toswallow the formulated product, or previous significant bowel resection that wouldpreclude adequate absorption of osimertinib.

7. Any of the following cardiac criteria:

• Mean resting corrected QT (QTc) interval > 470 msec, obtained from 3electrocardiograms (ECGs).

• Any clinically important abnormalities in rhythm, conduction, or morphology ofresting ECG.

• Any factors that increase the risk of QTc prolongation or risk of arrhythmicevents.

• Heart failure, congenital long QT interval (QT) syndrome, family history oflong QT syndrome or unexplained sudden death under 40 years of age infirst-degree relatives or any concomitant medication known to prolong the QTinterval and cause Torsades de Pointes (TdP).

8. Past medical history of interstitial lung disease (ILD), drug-induced ILD, radiationpneumonitis that required steroid treatment, or any evidence of clinically activeILD.

9. Inadequate bone marrow reserve or organ function.

10. Women who are breastfeeding.