A Study to Test How BI 764532 is Taken up by Tumours in People With Small-cell Lung Cancer or Neuroendocrine Cancer

This study is open to adults with small cell lung cancer and other neuroendocrine cancers. 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 out how a medicine called BI 764532 gets distributed in the body and in tumours. Participants get BI 764532 when starting treatment. In the first weeks, doctors check how BI 764532 is taken up in tumours by means of an imaging method. 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. Doctors record any unwanted effects and regularly check the general health of the participants.