16 Chapter 1 We performed a dose finding study to determine the feasibility of [89Zr]Zr-DFO-durvalumab PET/CT in SCCHN. Using the optimal dose, additional patients were included to correlate [89Zr]Zr-DFO-durvalumab-uptake to treatment response (chapter 5). PINNACLE study Simultaneously with the PINCH study, the PINNACLE (PD-L1 ImagiNg in Non smAll Cell Lung CancEr) study was designed to perform PD-L1 PET-imaging with [89Zr]Zr-DFO-avelumab in patients with resectable early-stage NSCLC or irresectable metastatic NSCLC. In this study, we focused on both patients with resectable early-stage NSCLC as well as patients with irresectable metastatic NSCLC. In chapter 6, we report the dose finding study and feasibility of [89Zr]Zr-DFO-avelumab PET-imaging to visualize tumor PD-L1 and correlate [89Zr]Zr-DFAavelumab-uptake to (pathological) response to avelumab treatment. Finally, we reflect on the experiences with clinical PD-(L)1 PET-imaging studies that have been performed so far, in chapter 7.