CD40 and Thromboembolism: However, considering the side-effect of CD40 agonists, such as potential toxicity due to autoimmune reactions, severe cytokine release syndrome (CRS), hyper-immune stimulation syndrome leading to AICD, thromboembolic disease and tumor proliferation or angiogenesis, the use of CD40 agonist antibodies is still limited and need much more study to verify their availability.