This study focuses on HER3-DXd, a treatment for specific types of lung cancer, especially when the cancer can't be removed with surgery or has spread to other parts of the body. Non-Small Cell Lung Cancer (NSCLC) is a type of lung cancer that grows and spreads slower than small cell lung cancer. The study has two main parts: dose escalation (testing different doses to find the safest) and dose expansion (testing the treatment's effectiveness). Participants have NSCLC with certain genetic mutations like EGFR or KRAS-G12C, which means changes in their DNA that can affect how the cancer grows. The study lasts about 36 months. Participants will stop if they want, if their cancer worsens, or if side effects are too severe.

• Study lasts around 36 months; participants may stop anytime.
• Participants must have advanced NSCLC with specific genetic mutations.
• Focus on safety, tolerability, and antitumor activity of HER3-DXd.