A Study to Investigate the Efficacy and Safety of Trastuzumab Deruxtecan as the First Treatment Option for Unresectable, Locally Advanced/Metastatic Non-Small Cell Lung Cancer With HER2 Mutations

Inclusion Criteria: * Participants at least 18 years of age * Locally advanced and unresectable NSCLC, not amenable to curative therapy, or metastatic disease * Histologically documented non-squamous NSCLC with HER2 mutation in exons 19 or 20 by tissue NGS or ctDNA * Treatment-naïve for palliative intent systemic therapy for locally advanced or metastatic disease * Left ventricular ejection fraction (LVEF) ≥ 50% * Measurable disease assessed by Investigator based on RECIST 1.1 * Protocol-defined adequate organ function including cardiac, renal, hepatic function * ECOG 0-1 * Having tumour tissue available for central testing Exclusion Criteria: * Tumors with targetable alterations to EGFR (or other targetable mutations including but not limited to ALK, if routinely tested as a targetable alteration with approved available therapy) * Any untreated brain metastases, including asymptomatic or clinically inactive brain metastases * Active autoimmune or inflammatory disorders * Medical history of myocardial infarction within 6 months prior to randomization * History of non-infectious pneumonitis/ILD, current or suspected ILD * Lung-specific intercurrent clinical significant severe illness * Contraindication to platinum-based doublet chemotherapy or pembrolizumab