This clinical trial is focused on studying the safety and initial effectiveness of a new treatment for patients with advanced malignant solid tumors. These are types of cancer that have spread to other parts of the body and are not easily removed by surgery. The trial will test a new medication called BNT314, which is given as a solution through an intravenous infusion, meaning it is delivered directly into the bloodstream. In some parts of the study, BNT314 will be used alone, while in others, it will be combined with another medication called pembrolizumab, also known by the brand name Keytruda. Pembrolizumab is an immune checkpoint inhibitor, a type of drug that helps the immune system recognize and attack cancer cells.

The purpose of the study is to find the best dose of BNT314 that can be safely given to patients and to see how well it works against cancer. The study will start with a phase called dose escalation, where different doses of BNT314 will be tested to find the maximum amount that can be given without causing severe side effects. After this, the study will move to a phase called dose expansion, where more patients will receive the treatment to gather more information about its safety and effectiveness. Some patients will receive BNT314 alone, while others will receive it in combination with pembrolizumab.

Throughout the study, patients will be closely monitored for any side effects and to see how their cancer responds to the treatment. The study aims to provide valuable information about the potential of BNT314 as a new treatment option for people with advanced cancer. The trial is expected to continue until 2027, with recruitment of participants starting in late 2023. Participants will receive regular check-ups and assessments to ensure their safety and to track the progress of their treatment.