Abstract 2875: p53 regulation of PDL1 is mediated through miR-34a

A Totipotent "All-In-One" Peptide Sequentially Blocks Immune Checkpoint and Reverses the Immunosuppressive Tumor Microenvironment

Immune checkpoint blockade combined with reversal of the immunosuppressive tumor microenvironment (TME) can dramatically enhance anti-tumor immunity, which can be achieved by using multiple-agent therapy. However, the optimal dose and order of administration of different agents remain elusive. To address this dilemma, multiple agents are often grafted together to construct "all-in-one" totipotent drugs, but this usually comes at the cost of a lack of synergy between the agents. Herein, by comprehensively analyzing the conserved sites of the immune checkpoint and TME drug targets, peptide secondary structures, assembly properties, and other physicochemical properties, a high-content peptide library is designed. By using the "3D-molecular-evolution" screening strategy, an efficient and totipotent "all-in-one" peptide (TAP) is obtained, which possesses the abilities of self-assembling, blocking the PD-1/PD-L1 axis, inhibiting Rbm38-eIF4E complex formation, and activating p53. It is shown that in mice treated with TAP, with either subcutaneous tumors or patient-derived xenografts, PD-L1 is blocked, with increased activation of both T and NK cells whilst reversing the immunosuppressive TME. Moreover, TAP can mitigate tumor activity and suppress tumor growth, showing superior therapeutic effect over antibody-based drugs.

miRNAs in Regulation of Tumor Microenvironment, Chemotherapy Resistance, Immunotherapy Modulation and miRNA Therapeutics in Cancer

miRNAs are 20-22 long nucleotide non-coding ribonucleic acid molecules critical to the modulation of molecular pathways. Immune evasion and the establishment of a suitable tumor microenvironment are two major contributors that support tumor invasion and metastasis. Tumorigenic miRNAs support these two hallmarks by desensitizing important tumor-sensitive regulatory cells such as dendritic cells, M1 macrophages, and T helper cells towards tumors while supporting infiltration and proliferation of immune cells like Treg cells, tumor-associated M2 macrophages that promote self-tolerance and chronic inflammation. miRNAs have a significant role in enhancing the efficacies of immunotherapy treatments like checkpoint blockade therapy, adoptive T cell therapy, and oncolytic virotherapy in cancer. A clear understanding of the role of miRNA can help scientists to formulate better-targeted treatment modalities. miRNA therapeutics have emerged as diverse class of nucleic acid-based molecules that can suppress oncogenic miRNAs and promote the expression of tumor suppressor miRNAs.