A Study to Test Different Doses of BI 3923948 Alone and in Combination With an Anti-PD-1 Antibody in People With Different Types of Advanced Cancer (Solid Tumors)

This study is open to adults aged 18 and over or above legal age with different types of recurrent advanced cancer (solid tumors) that have spread to other parts of the body and that are accessible for injection and biopsy. This is a study for people for whom previous treatment was not successful or no treatment exists, with a life expectancy of at least 3 months after starting study treatment. The purpose of this study is to find the highest dose of a medicine called BI 3923948, that people with advanced cancer can tolerate, when taken alone and together with a type of antibody called a checkpoint inhibitor (anti-programmed cell death protein 1 antibody). Another purpose is to check whether the study treatment can fight cancer. In this study, BI 3923948 is given to people for the first time. This study has 2 arms. In Arm A, participants get BI 3923948 alone for up to 3 months. In Arm B, participants get BI 3923948 in combination with a checkpoint inhibitor. Participants who take the combination treatment get BI 3923948 for up to 3 months and a checkpoint inhibitor for up to 1 year. BI 3923948 is given as injection(s) into the tumor, and the checkpoint inhibitor is given as an infusion into a vein. Participants get the medicines about every 3 weeks. This is called a treatment cycle. Only in treatment cycle 1 will participants get BI 3923948 twice in the first week. Participants visit the site study site regularly. The number of study visits vary based on the study arm and treatment response. Some visits include an overnight stay. The doctors regularly check the participants' health and monitor the tumors. The doctors closely check the health of the participants and also take note of any health problems that could have been caused by the study treatment.