Immunotherapeutic effects of intratumoral nanoplexed Poly I:C (B16-OVA cell line). Immunotherapeutic effects of intratumoral nanoplexed Poly I:C (B16-OVA cell line)

Poly I:C is a powerful immune adjuvant as a result of its agonist activities on TLR-3, MDA5 and RIG-I. Intratumoral administration is conceivably safer than systemic delivery and allows concentrate proinflammatory adjuvanticity in the tumor microenvironment and tumor-draining lymphoid tissue. BO-112 is a nanoplexed formulation of Poly I:C complexed with polyethylenimine that causes tumor cell apoptosis showing immunogenic cell death features and that upon intratumoral release results in more prominent tumor infiltration by T lymphocytes. Intratumoral treatment of subcutaneous tumors derived from MC38, 4T1 and B16F10 with BO-112 leads to remarkable local disease control mediated by CD8+ T lymphocytes, as concluded from selective depletion experiments. Some degree of control of non-injected tumor lesions upon BO-112 intratumoral treatment was found in mice bearing bilateral B16OVA melanomas, that was enhanced when co-treated with systemic anti-CD137 and anti-PD-L1 immunomodulatory mAbs. More abundant CD8+ T lymphocytes were found in tumor-draining lymph nodes and in the tumor microenvironment following intratumoral treatment with BO-112. Enhanced numbers of tumor-specific CTLs recognizing melanosomal antigens and ovalbumin were readily detected among them. Genome-wide transcriptome analyses of injected tumor lesions were consistent with a marked upregulation of the type-I interferon pathway. Intratumorally delivered BO-112 is being tested in cancer patients (NCT02828098) and our results in mice suggest prominent anti-tumor local control through its proimmune effects. To compare the in-vitro and in vivo transcriptional profile induced by BO-112, B16-OVA cell lines were incubated with BO-112 for 24h. BO-112 induces a specific transcriptional profile in B16-OVA cell cultures. Key immunoregulatory genes were found to be differentially expressed between BO-112 and Vehicle-incubated B16-OVA cells. Overall design: B16-OVA cells were incubated either with BO-112 at 0.5 µg/mL (n=3) or identical volumes of vehicle (5%glucose, n=3) for 24h