Senescence of tumor cells induced by oxaliplatin increases the efficiency of a lipid A immunotherapy via the recruitment of neutrophils.

Management of advanced colorectal cancer is challenging due to the lack of efficient therapy. The lipid A, OM-174 exhibited antitumor activity in colorectal cancer. We explored the anticancer efficacy of this compound in rats bearing large colorectal tumors in combination with the platinum derivative drugs oxaliplatin and cisplatin. While each drug used alone exhibited partial antitumor activity, sequential treatment with oxaliplatin or cisplatin for one week followed by lipid A injections induced a great regression of colorectal tumors, with more than 95% of rats cured from their tumors. This potent antitumor efficacy of the combined treatments was correlated to the sequential induction of cellular senescence by oxaliplatin, and of apoptosis, mainly triggered by the lipid A. Moreover, a recruitment of tumor-associated neutrophils with N1 phenotype as attested by the expression of inducible nitric oxide synthase was observed with combination of oxaliplatin and lipid A. Neutrophil recruitment within tumor microenvironment was due to oxaliplatin and lipid A-dependent release of neutrophil specific chemoattractants such as cxcl1 and 2. However the N1 phenotype is only dependent of lipid A treatment. These results suggest that the combination of chemotherapy with an immunotherapy is a promising approach to treat patients with advanced colorectal cancer.