This study focuses on a new drug, **BDTX-1535**, to treat *glioblastoma* (a type of brain cancer) and **non-small cell lung cancer (NSCLC)** with specific *epidermal growth factor receptor (EGFR)* mutations. The study is divided into two phases. Phase 1 is complete, while Phase 2 is open for enrollment. Patients will take the drug by mouth in 21-day cycles. The study aims to find the safest dose and see how the drug works in the body and against cancer. **Key points to consider:** - **Study Length & Visits**: Participation involves taking the medication at home and regular check-ups. - **Eligibility**: Must have advanced NSCLC with specific EGFR mutations or glioblastoma. - **Risks & Benefits**: Understand potential side effects and possible benefits of trying a new treatment. Participants need to have a confirmed diagnosis of NSCLC or glioblastoma and must meet specific criteria related to past treatments and current health status. Some conditions such as certain prior treatments, other health issues, or active infections could exclude participation. If considering this study, discuss with your doctor to understand all the details and implications.