Study of BEBT-109 in Subjects With EGFR Exon 20 Insertion Mutations Non-Small Cell Lung Cancer

This study is designed with two cohorts, each comprising approximately 100 subjects. Cohort 1 includes subjects with EGFR exon 20 insertion mutations in NSCLC who have failed or are intolerant to at least one systemic chemotherapy and have not received third-generation EGFR (Tyrosine Kinase Inhibitor) TKI therapy. Cohort 2 includes subjects with EGFR exon 20 insertion mutations in NSCLC who have failed or are intolerant to at least one systemic chemotherapy and have experienced Progressive Disease after receiving standard-dose third-generation EGFR TKI therapy.Subjects receive BEBT-109 capsules treatment with a dosage of 120mg bid (twice a day), and each 28-day period constitutes a cycle. In case of intolerance during the treatment, dose adjustments can be made according to the adjustment plan. Each subject's study process includes three phases: the screening period, the treatment period, and the post-treatment follow-up period. The screening period can last up to 28 days.During the treatment period, tumor assessments are conducted every 8 weeks (±7 days). If the initial response is Partial Response (PR) or Complete Response (CR ), a confirmation assessment for efficacy is required between 4-6 weeks. Subjects can continue to receive study medication until Progressive Disease (PD), death, intolerable toxicity occurs, or the subject withdraws informed consent (whichever comes first). After discontinuing treatment, subjects will enter the post-treatment follow-up period, receiving efficacy follow-ups every 8 weeks (±7 days) (until tumor progression or other anti-tumor treatments are administered) and survival follow-ups every 3 months (±7 days). When a subject experiences the first instance of Progressive Disease, if the investigator believes that continued use of the study medication may still be beneficial, the subject is allowed to continue receiving study medication until imaging indicates no clinical benefit.