A large case review linked the checkpoint inhibitor nivolumab to rare cytokine storm events, reinforcing that even established immunotherapies can produce severe immune-related toxicities in a small subset of patients. Researchers pooled real-world cases to characterize patterns and clinical circumstances around cytokine release syndrome-like presentations associated with nivolumab. Clinically, the update matters because early recognition remains critical for outcomes and for minimizing treatment interruption or ICU-level escalation. For trial and pharmacovigilance teams, the work supports tightening monitoring protocols and improving documentation of onset timing and co-factors. For biotech product teams, the broader implication is the need to maintain a safety narrative alongside efficacy differentiation, particularly as the class expands into broader combinations and line-of-therapy indications. (Selected item reflects the safety-focused review rather than primary efficacy claims.)