The main objectives of such an early phase clinical trial are safety and tolerability, pharmacokinetics and (in the case of radiopharmaceuticals) dosimetry aspects. For the first 6 patients, the focus of the study will be on safety, tolerability and pharmacokinetics. Therefore, both TKI-resistant and TKI-sensitive GIST patients will be included. As resistant patients are typically in 2nd- or 3rd-line TKI treatment prone to substantial side effects and potentially suffer from a greater extent of disease, the study design includes a limited number of non-resistant GIST patients to address a possible bias regarding tolerability and side effects profile of 68Ga-NeoBOMB1.