Rethinking Immune Checkpoint Inhibition in Cancer

Immune checkpoint inhibitors (ICIs) have reshaped cancer treatment, offering durable remissions for a minority of patients. Yet their success has come with a difficult trade-off: a large proportion of patients develop immune-related adverse events (irAEs), sometimes severe, and often without gaining clinical benefit. These reactions signal a disruption of peripheral tolerance that is not easily explained by traditional models in which negative selection of autoreactive T cells maintains self-restraint. Under ICI therapy, patients' own T cells can behave in ways that resemble the alloreactive responses seen in chronic graft-versus-host disease (cGVHD), producing a pattern of tissue injury that mirrors this well-studied transplant complication. This parallel offers a fresh way to think about why irAEs occur and how they might be prevented. Despite arising from fundamentally different immunologic triggers, comparative transcriptomic analyses reveal that cGVHD and irAEs induced by ICIs converge on a common molecular ecosystem dominated by interferon-conditioned tissue states. Early clinical experience with ultra-low-dose ICI regimens supports this idea, showing that meaningful antitumor activity can be preserved while dramatically reducing toxicity. We suggest that viewing ICI-induced autoimmunity through a cGVHD-like lens may help guide safer dosing strategies and broaden access to immunotherapy worldwide.