Inclusion Criteria:  

• Participant must have newly diagnosed histologically or cytologically confirmed, locally advanced or metastatic non-small cell lung cancer (NSCLC) that is treatment naive and not amenable to curative therapy including surgical resection or chemoradiation
• The tumor harbors exon 19 deletions (Exon 19del) or Exon 21 L858R substitution, as detected by an food and drug administration (FDA)-approved or other validated test in a clinical laboratory improvement amendments (CLIA) certified laboratory (sites in the United states [US]) or an accredited local laboratory (sites outside of the US) in accordance with site standard of care
• Mandatory submission of unstained tissue from tumor (in a quantity sufficient to allow for central analysis of EGFR mutation status and blood (for circulating tumor deoxyribonucleic acid [ctDNA], digital droplet polymerase chain reaction [ddPCR], and pharmacogenomic analysis)
• Any toxicities from prior anticancer therapy must have resolved to common terminology criteria for adverse events (CTCAE) Grade 1 or baseline level
• Participant must have at least 1 measurable lesion, according to response evaluation criteria in solid tumors (RECIST) v1.1 that has not been previously irradiated. Measurable lesions should not have been biopsied during screening, but if only 1 non-irradiated measurable lesion exists, it may undergo a diagnostic biopsy and be acceptable as a target lesion, provided the baseline tumor assessment scans are performed at least 14 days after the biopsy.

Exclusion Criteria:

• Participant has received any prior systemic treatment at any time for locally advanced Stage III or metastatic Stage IV disease (adjuvant or neoadjuvant therapy for Stage I or II disease is allowed, if administered more than 12 months prior to the development of locally advanced or metastatic disease).
• Participant has an active or past medical history of leptomeningeal disease.
• Participant with untreated spinal cord compression. A participant that has been definitively treated with surgery or radiation and has a stable neurological status for at least 2 weeks prior to randomization is eligible provided they are off corticosteroid treatment or receiving low-dose corticosteroid treatment less than or equal to (≤) 10 milligrams per day (mg/day) prednisone or equivalent.
• Participant has an active or past medical history of interstitial lung disease (ILD)/pneumonitis, including drug-induced or radiation ILD/pneumonitis.
• Participant has known allergy, hypersensitivity, or intolerance to the excipients used in formulation of amivantamab, lazertinib, or osimertinib, or any contraindication to the use of osimertinib.
• Participant has symptomatic brain metastases. A participant with asymptomatic or previously treated and stable brain metastases may participate in this study.

Eligibility last updated to match clinicaltrials.gov 2/16/22. Questions regarding updates should be directed to the study team contact.