Abstract Rationale Mechanism-specific therapies for idiopathic pulmonary fibrosis (IPF) like broadly acting TGF-b inhibitors have failed in clinical trials, largely due to off-target effects. Thus, IPF continues to be uniformly fatal without lung transplant. A fundamental unsolved challenge in treating IPF remains: how to effectively modulate dysregulated signaling pathways in specific cells responsible for pathologic fibrosis in living organisms while avoiding toxicity in unrelated cells or tissues. Here, we take advantage of synthetic biology tools, like chimeric antigen receptor (CAR) and synthetic notch receptor (SynNotch) classically used to engineer cancer therapeutics and repurpose them to target the fibrotic lung. This will lay the groundwork for new tools that could revolutionize how we study and treat IPF and other poorly understood lung diseases: engineered cells modulating signaling pathways in real time in-vivo. Methods SynNotch receptors allow transcriptional activation of desired payloads only upon engagement with a chosen surface antigen. We engineered a SynNotch receptor that recognizes a lung-specific type I alveolar epithelial cell surface protein, RAGE, and a CAR that recognizes a splice form of tenascin C (tenascin C domain D; TNC-D) extracellular matrix protein that is only expressed in regions of pathologic fibrosis in the lung. After in-vitro validation proved that they recognize their target proteins, we tested both receptors expressed in human T cells and injected into mice challenged either with lung tumors (RAGE SynNotch) or bleomycin (TNC-D CAR). Results In mouse dual lung and flank tumor models, when an antitumor CAR was the payload for RAGE SynNotch, tumors are cleared in the lung but not the flank. In a lung sarcoma model where anti-GD2 CAR T cells that effectively clear tumors but cannot be used as therapeutics due to off target toxicities in the gut and brain, T cells with a RAGE SynNotch to GD2 CAR circuit enable effective tumor killing in the lung without off target toxicities, confirming lung-specific expression of the payload. TNC-D CAR-T cells proliferate and persist in fibrotic regions of the lung in mouse models of pulmonary fibrosis and reduce hydroxyproline content, a surrogate for overall pulmonary fibrosis. Conclusions We can target the lung (RAGE SynNotch) and specific regions of fibrosis in the lung (TNC-D CAR) using novel synthetic biology tools. These tools will enable delivery of signaling pathway modulators like TGF-b inhibitors specifically to areas of lung fibrosis in vivo and represent the first steps towards mechanism-specific cell-based therapies for IPF. This abstract is funded by: NHLBI, ARPA-H
A Jacob (Fri,) studied this question.