First discovered in 1997 the torque teno virus (TTV) can be found in the vast majority of the human population throughout their lifetime. The TTV levels correlate with infectious diseases and organ rejection and are therefore currently being investigated as a tool to optimize the management of patients after solid organ transplantation (SOT). While TTV levels are already tested to guide immunosuppressive therapy its significance for oncologic patients is unclear. In recent years immune checkpoint inhibitors (ICIs) are increasingly implemented in multimodal therapy approaches for patients with non-small-cell lung cancer (NSCLC). Since ICI and TTV levels depend on T-cell function, the TTV load may be a relevant biomarker for the treatment response as well as complication risk after ICI therapy. Current standard imaging using PERCIST and RECIST criteria is prone to misinterpretation of treatment response of ICI therapy due to pseudoprogression and nodal immune flaring. This study aims to prospectively analyze TTV levels in NSCLC patients before, during and after neoadjuvant chemo-immunotherapy and correlate inter- and intraindividual changes in TTV levels with response rates observed on PET/CT restaging and histopathological response rates as well as postoperative outcome.