This is a global study to assess the effects of osimertinib in participants with EGFRm stage IA2-IA3 non-small cell lung cancer following complete tumour resection.

This is a Phase III, double-blind, randomised, placebo-controlled, 2-arm, international study assessing the efficacy and safety of adjuvant osimertinib versus placebo in participants with stage IA2-IA3 EGFRm Non-Small Cell Lung Cancer, who have previously undergone complete tumour resection. All participants must have had a tumour which harbours one of the 2 common EGFR mutations known to be associated with EGFR-TKI sensitivity (Ex19del, L858R).

Eligible participants will be randomised in a 1:1 ratio to one of the 2 intervention arms: osimertinib 80 mg or matching placebo, once daily for 3 years unless discontinuation criteria is met.

Inclusion Criteria

1. Male or female, at least ≥ 18 years.
2. NSCLC, of non-squamous histology.
3. Stage IA2 or IA3 disease, based on TNM8 classification.
4. Complete surgical resection (R0) of the primary NSCLC by lobectomy, bilobectomy, segmentectomy or sleeve resection.
5. Complete recovery from surgery at the time of randomisation. Study intervention cannot commence within 4 weeks following surgery. No more than 12 weeks may have elapsed between surgery and randomisation for participants.
6. World Health Organization performance status of 0 or 1.
7. Provision of tumour sample for central pathology assessment of pathologic risk factors and to assess EGFR mutation status prior to randomisation.
8. A tumour which harbours one of the 2 EGFR mutations (Ex19del, L858R) by cobas® EGFR Mutation Test v2 (Roche Diagnostics) or FoundationOne® test.
9. Minimum life expectancy of > 6 months.
10. Females must be using highly effective contraceptive measures, 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. Male subjects must be willing to use barrier contraception.

Exclusion Criteria

1. Mixed small cell and non-small cell cancer history.

2. Participants with incomplete (R1/R2) resection, or who have undergone pneumonectomy or only wedge resection.

3. Any evidence of severe or uncontrolled systemic diseases, including uncontrolled hypertension and active bleeding diatheses; or active infection including HCV and HIV or active uncontrolled HBV infection.

4. History of another primary malignancy, including any known or suspected synchronous primary lung cancer except for malignancy treated with curative intent with no known active disease ≥ 5 years before the first dose of study intervention and of low potential risk for recurrence.

5. Any of the following cardiac criteria:

   • Mean resting QTcF interval > 470 ms, obtained from triplicate ECGs performed at screening.
   • Any abnormalities in rhythm, conduction, or morphology of resting ECG,
   • Any factors that increase the risk of QTcF prolongation or risk of arrhythmic events.

6. History of interstitial lung disease.

7. Inadequate bone marrow reserve or organ function.

8. Any unresolved toxicities from prior therapy greater than CTCAE Grade 1 at the time of starting study intervention.

9. Prior treatment with any anticancer therapy for NSCLC (including chemotherapy, radiotherapy, immunotherapy, and EGFR-TKIs).

10. Major surgery or significant traumatic injury within 4 weeks of the first dose of study intervention.

11. Participants currently receiving medications or herbal supplements known to be strong inducers of CYP3A4.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal.

All request will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please refer to our disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved, AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool. Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.