981 Tumor-mediated innate training of neutrophil progenitors involves FOXO1 activation and promotes immunotherapy-associated colitis
Year: 2026
Type: conference-abstract
Abstract: Background Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many cancers, but their use is limited by the development of immune-related adverse events (irAEs). Corticosteroids are the standard first-line treatment for moderate to severe irAEs; however, many irAEs exhibit resistance to these agents. Neutrophils have emerged as key mediators of these steroid-refractory toxicities. Activated neutrophils contribute to tissue damage and ongoing inflammation by producing reactive oxygen species, releasing proteases, and forming neutrophil extracellular traps. We have demonstrated that a tumor-intrinsic NLRP3-HSP70 signaling axis enhances systemic neutrophil levels associated with the development of checkpoint inhibitor-associated colitis. However, how tumor-intrinsic NLRP3 influences toxicity still remained unclear. We hypothesized that tumor-intrinsic NLRP3 activity reprograms neutrophil dynamics at the progenitor level, thereby facilitating inflammatory colitis during immunotherapy.Methods We have applied single-cell RNAseq/ATAC sequencing, multi-parameter flow cytometry, and immunofluorescence microscopy to newly engineered transgenic tumor models and tissue-specific knockout models undergoing checkpoint inhibitor immunotherapy. Inflammatory colitis was monitored using immunohistochemistry, flow cytometry, micro-PET CT imaging, and stool calprotectin quantification. Bone marrow chimera experiments were performed to confirm that tumor-conditioned neutrophil progenitors mediate colitis in response to ICI therapy.Results Using various transgenic and orthotopic tumor models, we have found that ICI-induced colitis develops in a tumor-dependent manner. Mice that have received bone marrow transplants from tumor-exposed donors exhibit ICI-associated inflammatory colitis while mice receiving bone marrow transplants from non-tumor-exposed donors do not. Melanoma-specific Nlrp3 genetic silencing in a transgenic model suppresses ICI-associated colitis in response to neoadjuvant and adjuvant ICI therapy. Neutrophil progenitor populations from tumor-bearing mice exhibit alterations in chromatin accessibility and enhanced activity of the FOXO1 transcription factor relative to non-tumor-bearing mice controls. Inhibition of FOXO1 in these neutrophil progenitors reduces neutrophil proliferation and differentiation into CXCR2+ migratory neutrophils. Pharmacologic inhibition of FOXO1 in melanoma-bearing mice during immunotherapy inhibited neutrophil accumulation and TH17 tissue infiltration in the colon and attenuated toxicity. Baseline plasma HSP70 and IL-17a levels correlate with the development of more severe irAEs in stage IV melanoma patients undergoing ICI therapy.Conclusions The tumor intrinsic NLRP3-FOXO1 axis primes the innate immune compartment and facilitates IL-17-mediated colitis during immunotherapy. These findings support targeting tumor-intrinsic NLRP3 to mitigate immunotherapy-associated toxicity while preserving anti- tumor efficacy. Tumor-mediated innate training of neutrophil progenitors influences the development of select irAEs and represents a novel source of pharmacologic targets and predictive biomarkers worthy of future clinical study.
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,490
OpenAlex ID: W7225137906