Program the Immune System against RAS-driven Cancer

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Abstract Despite the great progress in recent decades, many types of cancer remain almost fatal. Pancreatic ductal adenocarcinoma (PDAC) is a remarkable example. One of the challenges is that the vast majority (95%) of PDACs are driven by mutations within a gene called KRAS, and these KRAS mutations are notoriously difficult to target with conventional drugs. The first generation of cancer drugs are based on small molecules, the second generation biologics (large biomolecules such as antibodies that specifically bind to cancer cells), and the latest generation cells (engineered to recognize and ablate cancer cells). Here our long-term goal is to demonstrate a new generation of therapeutics, using “circuits” as medicine. Circuits metaphorically refer to collections of biomolecules engineered to regulate each other and process information inside living cells. While conventional analyses output metrics to inform physicians, who then make therapeutic decisions, our circuits close the loop, and will serve as both the analytic and the therapeutic tools. It is a molecular and cellular analysis technology that queries living cells and actuates therapeutic outputs in real time without human intervention. Specifically, we will create circuits to program the immune system and emulate the “abscopal effect”, the occasional observation that distant tumors shrink when local tumors are treated, most likely due to the immune system learning the “signature” of the treated tumors and then extrapolating. We will first create the building blocks for such circuits: sensors that can interrogate whether a cell is in a cancerous state, actuators that can control the signals sent by cells to engage the immune system, and processors that connect the sensors and the actuators. These efforts will benefit from our experience of building circuits exclusively using proteins, which features technical advantages, such as ease of delivery and robustness of functionality in different cellular contexts, compared to more conventional ways of building circuits based on protein-DNA interactions. We will then assemble these building blocks into circuits, and quantify and optimize their operation in cultured cells. Leveraging our expertise in mouse models of PDACs, we will finally test these circuits’ efficacy in vivo. The premise is to program the outputs specifically from cancer cells to mobilize the immune system and then lyse these cells to grant the immune system access to all protein sequences that are uniquely present in cancer. These dead cancer cells will serve essentially as vaccines against other cells that exhibit similar protein sequence profiles. We will achieve this vaccination effect by either mimicking a specific type of cell death known to mobilize the immune system, or program the cancer cells to directly and artificially activate T cells – immune cells responsible for recognizing and ablating cancer cells. The expected outcomes of this proposal are not only preclinical evidence supporting a novel, powerful therapy for KRAS-driven PDAC, but also a proof of principle for the biomedical promise of synthetic biomolecular circuits for other recalcitrant types of cancer and beyond.