CTLA4 and neoplasm: Importantly, higher baseline levels of soluble CTLA-4 (sCTLA-4) have been proposed as possibly predictive of immune toxicity in melanoma patients treated with anti-CTLA-4 antibody, especially gastrointestinal irAEs (Pistillo et al., 2019), although to some extent, high levels of sCTLA-4 may also reflect tumor immune escape and high tumor burden (Ward et al., 2013).