Fiber-Boost Randomized Controlled Trial

In the present study 'Fiber-Boost', we investigate how a high-fiber diet affects the immunotherapy of advanced lung cancer and what effects it has on the gut microbiome (i.e., the bacteria in the gut) as well as the immune system. Study participants will be assigned to either a test group or a control group. Only patients in the test group will undergo a high-fiber diet. The study lasts 6 weeks per patient and will be conducted at 4 centers within Switzerland. A total of 42 patients are planned to be included in the study.

The activity of immune checkpoint blockade (ICB) mechanistically depends on the host microbiome and is manipulable through diet. In this study termed Fiber-Boost, we propose a multicenter trial of a supplement-based high-fiber diet (HFD) in non-small cell lung cancer (NSCLC) treated with first-line ICB monotherapy. Using a randomized, controlled design, we mechanistically explore the role of dietary fibers in cancer immunotherapy. Circulating tumor DNA (ctDNA) quantification as well as a rich pipeline of companion microbiome and immune profiling technologies will improve the understanding of the diet-microbiome-immune axis in therapeutic anticancer immunity and treatment response. The overarching goal is to elucidate novel therapeutic strategies for ICB sensitization in NSCLC using microbiome-centered, non-pharmaceutical interventions. Sex and gender dimensions are biologically not sufficiently relevant for the current study to merit corresponding stratification or analyses.