Adverse events

Participants were administered lazertinib 240 milligrams (mg) tablet orally once daily from Cycle 1 Day 1 until Cycle 15, with each cycle consisting of 28 days. Participants then received amivantamab subcutaneous injection with at dose 1600 mg (if body weight \[BW\] is less than \[\<\] 80 kilograms \[kg\]) or 2240 mg (if BW is greater than or equal to \[\>=\] 80 kg) co-formulated (SC-CF) with recombinant human hyaluronidase PH20 (rHuPH20) 160 milligrams per milliliter (mg/mL) through manual injection on Cycle 1 Days 1, 8, 15, and 22, and on Days 1 and 15 of each subsequent cycle, starting from Cycle 2. After the completion of primary analysis, participants who benefited from the study treatment continued their treatment within the study upon transitioning into the LTE phase.

Participants were administered lazertinib 240 mg orally once daily from Cycle 1 Day 1 until Cycle 15, with each cycle consisting of 28 days. Participants then received amivantamab intravenous infusion at dose 1050 mg (if BW\< 80 kg) or 1400 mg (if BW \>=80 kg) on Cycle 1 Days 1-2 (split dose), 8, 15, 22, and on Days 1 and 15 of each subsequent cycle, starting from Cycle 2. After the completion of primary analysis, participants who benefited from the study treatment continued their treatment within the study upon transitioning into the LTE phase.