Anticancer Effects of Sublingual Type I IFN in Combination with Chemotherapy in Implantable and Spontaneous Tumor Models.

Salivary gland tumors are a heterogeneous group of neoplasms representing less than 10% of all head and neck tumors. Among salivary gland tumors, salivary duct carcinoma (SDC) is a rare, but highly aggressive malignant tumor resembling ductal breast carcinoma. Sublingual treatments are promising for SDC due to the induction of both local and systemic biological effects and to reduced systemic toxicity compared to other administration routes. In the present study, we first established that the sublingual administration of type I IFN (IFN-I) is safe and feasible, and exerts antitumor effects both as monotherapy and in combination with chemotherapy in transplantable tumor models, i.e., B16-OVA melanoma and EG.7-OVA lymphoma. Subsequently, we proved that sublingual IFN-I in combination with cyclophosphamide (CTX) induces a long-lasting reduction of tumor mass in NeuT transgenic mice that spontaneously develop SDC. Most importantly, tumor shrinkage in NeuT transgenic micewas accompanied by the emergence of tumor-specific cellular immune responses both in the blood and in the tumor tissue. Altogether, these results provide evidence that sublingual IFN holds promise in combination with chemotherapy for the treatment of cancer.

Tumor-Intrinsic or Drug-Induced Immunogenicity Dictates the Therapeutic Success of the PD1/PDL Axis Blockade.

Immunotherapy with immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment providing unprecedented clinical benefits. However, many patients do not respond to ICIs as monotherapy or develop resistance. Combining ICI-based immunotherapy with chemotherapy is a promising strategy to increase response rates, but few rationale-driven chemo-immunotherapy combinations have reached the clinical arena thus far. In the present study, we show that combined anti-PDL1 and anti-PDL2 antibodies optimally synergize with cyclophosphamide but not with cisplatin, and that the magnitude and duration of the therapeutic response is dependent on the immunogenic potential of the drug and of the tumor itself. Hallmarks of successful therapeutic outcomes were the enhanced infiltration by myeloid (mainly cross-presenting dendritic cells, eosinophils, and monocytic myeloid cells) and T lymphocytes into the tumor tissue and the expansion of circulating memory pools. Overall, our results suggest that immunomodulating chemotherapy can be exploited to increase the efficacy of PD1/PDL axis inhibitors in vivo, and that the magnitude of the synergic therapeutic response is affected by tumor-intrinsic immunogenicity.

Enzyme-linked immunospot assay to monitor antigen-specific cellular immune responses in mouse tumor models.

Critical to the advancement of tumor immunotherapy is the reliable identification of responders and the quantification of the tumor-specific immune response elicited by treatments. In this regard, Enzyme-Linked Immunospot assay (ELISpot) is an ideal monitoring technique due to its high sensitivity, ease of execution and cost-effectiveness. Originally developed for the enumeration of B cells secreting antigen-specific antibodies, ELISpot assay has been adapted to detect and quantify cytokine-secreting immune cells present at low frequency in a variety of biological samples, including blood, in response to antigen-specific stimuli. The above-mentioned features emphasize the role of ELISpot as valuable assay for translational research and clinical applications. In the present chapter, we will focus on the use of ELISpot assay for monitoring the tumor-specific effector responses induced by different treatments in preclinical models and will provide some protocols and technical hints for its application.