The bilateral interplay between cancer immunotherapies and neutrophils` phenotypes and sub-populations

INTRODUCTION: Immunotherapy has become a leading modality for the treatment of cancer but despite its increasing success, a substantial number of patients do not benefit from it. Cancer-related neutrophils became in recent years a subject of growing interest in cancer research. Excitingly, distinct sub-populations of neutrophils have been identified at advanced stages of cancer, some presenting anti-tumor properties (e.g. high density neutrophils (HDN)), whereas others show pro-tumor phenotype (e.g. low density neutrophils (LDN)), suggesting them as potential targets of therapy. We aim to evaluate in animal models of lung cancer the immunological consequences of manipulating the amount of circulating neutrophil subsets on tumor development and on the efficacy of anti-PD-1 therapy, and assess the impact of immunotherapy on neutrophils` phenotype.

METHODS: C57/129 mice were injected subcutaneously to the flank with LKR-M cells (Lung K-Ras metastatic tumor model). Fifteen days following injection, tumor-bearing mice were injected intraperitoneally with combinations of two different treatments: 1- 5x10⁶ HDN previously isolated from LKR-M-tumor-bearing mice for three subsequent days; 2- 150μg anti-PD-1 antibody every three days for two weeks with or without HDN. Tumor growth was monitored and the immune composition of the primary tumor and blood was assessed, together with phenotypic markers of neutrophils, using flow cytometry.

RESULTS: Tumor growth in the PD1-treated or HDN-treated mice is reduced compared to control groups. Both treatment types alter tumor composition, including an increase in the infiltration of tumor-associated neutrophils (TANs) and CD8⁺ T Cells. Preliminary results suggest that the expression levels of CCR2 (chemotaxis), 4-1BBL, OX40L (costimulatory molecules), ICAM-1 (Adhesion Molecules), CD62-L (neutrophil aging) and PDL-1 (checkpoint) are modulated in TANs following anti-PD-1 therapy. The impact of an anti- PD-1/HDN combination on tumor growth rate and immune responses is currently being investigated.

CONCLUSION: Together, our results suggest that neutrophils are modulated following anti-PD-1 treatment and could potentially improve the efficacy of immunotherapy. The outcome of this research could help us develop new strategies to direct the immune system against the tumor, and potentially improve the exciting new modality of immunotherapy in cancer.