Theranostic CAR-T Targeting Senescence in Alzheimer's - Project Summary / Abstract The increasing elderly population is resulting in a rise in age-related disorders. More than 95% of Alzheimer's disease (AD) instances are observed in individuals aged 65 or above, impacting over 11% of people within this age group. Cellular senescence is a key player in the aging mechanisms and plays a role in the onset of various age-related conditions, including AD, AD-related dementias (ADRD), and other neurodegenerative disorders. The removal of senescent cells has shown encouraging therapeutic results as a promising direction in reversing senescence and aging associated pathologies. Detecting and imaging senescent cells is critical for understanding the mechanisms of aging and associated disorders, and for guiding the removal of senescent cells. In addition to small molecule-based senolytics, the chimeric antigen receptor (CAR) T cell immunotherapy has recently been successfully applied as a novel strategy to target senescent cells in cancer and fibrosis models. However, CAR T cells in general suffer from various off-site toxicities, which represent a major impediment for a broader application of CAR T cell therapies. We propose to develop a novel concept of theranostic (therapeutic and diagnostic) CAR T cell platform based on unique theranostic probes and the signal-sensing chemically-induced proximity (sCIP) technology that selectively detect/report senescent cells, and also allows CAR T cells to respond to both “senescence-associated surface antigens” (on-target) and “senescence-associated chemical reactivities” that are presented within senescent cells (on- site), while limiting off-site activation of CAR T cells and the associated toxicities. To demonstrate this novel theranostic CAR T strategy, we propose to incorporate abscisic acid (ABA)-based sCIP technology to create and test theranostic ABA inducer that respond selectively to senescence-associated b-galactosidase (SA-b- Gal) and different CAR constructs specific to urokinase plasminogen activator surface receptor (uPAR) antigen on senescent cell surface. An additional inducible gene expression cassette introduced in CAR T cells can selectively produce therapeutic proteins in situ upon SA-b-Gal stimulation. In R61 phase, we will develop the theranostic CAR T platforms, which include the senescence-responsive theranostic ABA inducer (Aim 1), and the development of split CAR (sCAR) T cells and evaluate their efficacy in vitro (Aim 2). Since AD mice model will be used in the next phase and it takes time to develop, we will also start establishing AD mice models and colonies (Aim 3). In R33 phase, we will evaluate the theranostic ABA inducer (Aim 4), and the activation of sCAR-T in AD mice models (Aim 5). The efficacy of the theranostic CAR T therapy will be evaluated in AD mice using behavioral assays and MRI (Aim 6). We anticipate that our novel approach will have a broad impact on the development of AD therapeutics and it will also advance both senotherapies and CAR T therapies.
