Background Immune checkpoint inhibitors (ICI) are anti-cancer drugs that act by enhancing anti-tumour immunity. Due to their mechanism of action, they have been associated with immune related adverse events (Ir-AE), including musculoskeletal manifestations. Aim To assess a) the prevalence, clinical and imaging (MRI) characteristics of ICI-induced musculoskeletal immune related adverse events (ir-AE) in a prospective manner, b) the potential association of musculoskeletal ir-AE with oncologic response and changes in the immune system at the level of soluble molecules (cytokines) as well as T/B cell subpopulations. Methods This a multicentre prospective study. We plan to recruit all patients who are going to start treatment with ICI from October 2019 until October 2020 in all collaborating Oncology Departments. This study is consisted of a clinical and a laboratory arm. Results The study is currently recruiting patients. Conclusions We anticipate that this study will provide useful data regarding the clinical characteristics of ICI-induced musculoskeletal manifestations as well as potential predictive biomarkers.