PROJECT SUMMARY Despite the success of immunotherapies across several cancers, immunogenicity in solid tumors remains a major problem, pointing to the need to re-invent immunotherapeutic approaches and technologies. Checkpoint immunotherapies do not show the same response across patients with the same cancer, and neither mutational burden, DNA damage or expression of checkpoint proteins can accurately predict immunotherapy response. In addition, the progress on cancer vaccines has been limited by the lack of cancer specific and highly immunogenic antigens, antigen-delivery technology, and biomarkers to guide treatment. Based on these limitations in current cancer immunotherapies, we need to discover unconventional and unidentified mechanisms that regulate anti-tumor activity in aggressive cancers. The Programs presented seek to reveal how defective RNA splicing and anti- bacterial memory in T-cells determine the fate of anti-tumor immunity. By studying these mechanisms, we will have evidence for the development of novel and effective immunotherapies with penetrable delivery and tumor specificity. The long-term goal is to develop checkpoint immunotherapies and cancer vaccines that overcome immune ignorance, escape, and suppression in solid tumors. The project objective is to understand the intrinsic mechanisms of gene expression and antigen recognition that either inhibit or promote T-cell activity against tumor cells and develop checkpoint immunotherapies and cancer vaccines to unleash the full cytotoxic activity of T cells. In Program 1, we will dive deeper into the transcriptome of T-cells, where our preliminary data suggests that specific RNA splicing alterations in tumor infiltrating T-cells impact their maturation and function. Here we will evaluate the function of these splicing defects and test the therapeutic potential of correcting splicing alterations via our patented oligotherapy in pre-clinical models. In Program 2, we build on our discovery of an embryonic transcription program that acts as a bacterial virulence factor and is turned on in solid tumors associated with worst patient outcome. We will determine the role of acquired anti-bacterial immunity in cancer progression and test a novel cancer vaccine based on the expression of this biomarker as an approach to re-ignite anti-tumor activity. These programs are designed to test biological mechanisms that have not been appreciated in the context of immuno-oncology as therapeutic targets and could yield novel immunotherapies targeted at patient and tumor specific features.

PROJECT NARRATIVE The most aggressive solid malignancies evade immune surveillance and destruction and are refractory to the best available immunotherapies. Here we aim to evoke anti-tumor immunocompetence through 2 programs: 1) Identification and repair of altered RNA splicing in T cells to unleash anti-tumor immunity, and 2) Restoring anti-tumor function through vaccination against bacterial virulence factors mimicked by tumor antigens. These programs are designed to shed light on how known biological mechanisms, never explored in the context of immuno-oncology, could serve as therapeutic targets.