117P - Overcoming therapeutic resistance in colorectal cancer by inhibiting neutrophil extracellular traps

Background

Necrosis, a known predictor of poor prognosis in colorectal cancer (CRC), is thought to be a non-targetable process. We have previously shown that Neutrophil Extracellular Traps (NETs), web-like structures of chromatin and cytotoxic proteins, directly cause necrosis in murine breast and lung cancer models. We hypothesize that NETs also induce necrosis and promote metastasis in CRC, and mediate therapeutic resistance.

Methods

Resected primary CRC (n=47) and liver metastases (n=16) were scored for necrosis and compared with clinical outcomes and immunophenotypes. NETs were analyzed in blood samples from patients and healthy controls. A subset of tumors (necrotic vs non-necrotic) underwent single-cell RNA sequencing (ScRNA). Immune cells in blood, tumor, and bone marrow were profiled during tumor progression (8 weeks) using a CRC mouse model of orthotopic endoscopy-guided implantation of AKPS organoids (APC^KDKRAS^G12DP53^KOSMAD4^KO), which recapitulates human disease progression and therapy resistance. Tumor-bearing mice were treated with disulfiram (inhibitor of NET release) and chemotherapy (FOLFOX) to study the role of NETs in tumor necrosis and therapy resistance.

Results

NET-forming neutrophils (PMNs) were 3-fold higher in CRC patients compared to healthy controls. Necrotic tumor regions harbored 15-fold more NETs compared to non-necrotic regions. Extent of necrosis correlated with stage (p=0.007) and MMR status (p=0.01), but not tumor size (p=0.99). ScRNA gene expression of cancer cells in necrotic tumors had enrichment in migration and epithelial-to-mesenchymal transition pathways compared to non-necrotic tumors. In mice, CRC tumors induced a myeloid bias in bone marrow with expansion of PMNs in blood during tumor progression. NET blockade decreased NET formation by 50% and necrosis by 51%, with a preliminary trend toward decreased metastatic area in lung and liver. NET blockade with chemotherapy reduced tumor size by 60% and 31% compared to no treatment and chemotherapy alone, respectively.

Conclusions

Presence of NETs and NET-forming PMNs in CRC patient blood and tumors correlated with tumor necrosis. In mice, NET blockade not only decreased necrosis and metastasis, but also enhanced chemotherapy response.

Legal entity responsible for the study

The authors.

Funding

Northwell Health/Cold Spring Harbor Health Fund.

Disclosure

All authors have declared no conflicts of interest.