• Histologically confirmed diagnosis of primary NSCLC on predominantly non-squamous histology.

• Documented EGFRmt status as determined by local testing performed at a clinical laboratory improvement amendment (CLIA) certified (United States \[US\]) or accredited (outside of the US) local laboratory, defined as either one of the following EGFRmt:

‣ exon20 insertion mutations (ex20ins) or

⁃ other uncommon, non-ex20ins EGFRmt (eg, G719X, L861Q, or S768I)

• Magnetic resonance imaging (MRI) or computed tomography (CT) scan of the brain done prior to surgery. Participants in whom this was not done prior to surgery may still be enrolled if appropriate imaging (i.e., MRI or CT of the brain) is performed prior to randomization.

• Complete surgical resection of the primary NSCLC is mandatory. All gross disease must have been removed at the end of surgery. All surgical margins of resection must be negative for tumor. Resection may be accomplished by open thoracotomy or video associated thoracic surgery (VATS) techniques.

• Classified post-operatively as either Stage IB, IIA, IIB, or IIIA according to the tumor nodes metastasis (TNM) staging system for lung cancer (American Joint Committee on Cancer \[AJCC\] 9th edition).

• Complete recovery from surgery at the time of randomization.

• Eastern cooperative oncology group performance status (ECOG PS) of 0 or 1.

• Archival tumor tissue available for submission, with minimum quantity sufficient to evaluate EGFRmt status and, where possible, other biomarkers.