DAREON™-5: A Study to Test Whether Different Doses of BI 764532 Help People With Small Cell Lung Cancer or Other Neuroendocrine Cancers

This study is open to adults with small cell lung cancer and other neuroendocrine tumours. The study is in people with advanced cancer for whom previous treatment was not successful or no standard treatment exists. The purpose of this study is to find a suitable dose of BI 764532 (also called obrixtamig) that people with advanced cancer can tolerate. 2 different doses of BI 764532 are tested in this study. Another purpose is to check whether BI 764532 can make tumours shrink. BI 764532 is an antibody-like molecule (DLL3/CD3 bispecific) that may help the immune system fight cancer. The study has 3 parts. In Part 1, participants are put into 2 groups randomly, which means by chance. Participants have an equal chance of being in either group. One group gets dose 1 of BI 764532 and the other group gets dose 2 of BI 764532. In Part 2 and Part 3, all participants receive the same dose of BI 764532. Part 2 and Part 3 are open to people with a certain kind of tumour called extrapulmonary neuroendocrine carcinoma. All participants receive BI 764532 as an infusion into a vein when starting treatment. If there is benefit for the participants and if they can tolerate it, the treatment is given up to the maximum duration of the study. During this time, participants visit the study site regularly. The total number of visits depends on how they respond to and tolerate the treatment. The first study visits include an overnight stay to monitor participants´ safety. Doctors record any unwanted effects and regularly check the general health of the participants.