A Study of Mobocertinib in Japanese Adults With Non-Small Cell Lung Cancer

This study is in 2 parts. Different participants will take part in the 1st and 2nd parts of the study. The main aim of the 1st part of the study is to check how much Mobocertinib adults with non-small cell lung cancer (NSCLC) can receive without getting side effects from it. The main aim of the 2nd part of the study is to learn if the condition of adults with non-small cell lung cancer improves after treatment with Mobocertinib. Another aim is to continue checking for side effects from Mobocertinib. In the 1st part of the study, at the first visit, the study doctor will check who can take part. For those that can take part, participants will take a capsule of Mobocertinib once a day for 28 days. This will count as 1 cycle. Different small groups of participants will receive lower to higher doses of Mobocertinib. The study doctors will check for side effects after each dose of TAK 788. In this way, researchers can work out the best dose of Mobocertinib to give participants in the 2nd part of the study. Participants will visit the clinic 30 days after their treatment has finished for a final check-up. In the 2nd part of the study, at the first visit, the study doctor will check who can take part. Participants will receive the best dose of Mobocertinib worked out from the 1st part of the study. Participants will receive Mobocertinib in the same way as those from the 1st part of the study. The study doctors will learn if the condition of these participants improves after treatment with Mobocertinib. The study doctors will also check for side effects from Mobocertinib. After treatment has finished, participants will visit the clinic every 12 weeks until the end of the study. In both parts of the study, participants can receive Mobocertinib for up to just over 1 year, or longer if their condition stays improved.