Anti-inflammatory clearance of amyloid-ß by a chimeric Gas6 fusion protein.

Clearing amyloid-ß (Aß) through immunotherapy is one of the most promising therapeutic approaches to Alzheimer's disease (AD). Although several monoclonal antibodies against Aß have been shown to substantially reduce Aß burden in patients with AD, their effects on improving cognitive function remain marginal. In addition, a significant portion of patients treated with Aß-targeting antibodies experience brain edema and microhemorrhage associated with antibody-mediated Fc receptor activation in the brain. Here, we develop a phagocytosis inducer for Aß consisting of a single-chain variable fragment of an Aß-targeting monoclonal antibody fused with a truncated receptor binding domain of growth arrest-specific 6 (Gas6), a bridging molecule for the clearance of dead cells via TAM (TYRO3, AXL, and MERTK) receptors. This chimeric fusion protein (αAß-Gas6) selectively eliminates Aß plaques through TAM receptor-dependent phagocytosis without inducing NF-kB-mediated inflammatory responses or reactive gliosis. Furthermore, αAß-Gas6 can induce synergistic clearance of Aß by activating both microglial and astrocytic phagocytosis, resulting in better behavioral outcomes with substantially reduced synapse elimination and microhemorrhage in AD and cerebral amyloid angiopathy model mice compared with Aß antibody treatment. Our results suggest that αAß-Gas6 could be a novel immunotherapeutic agent for AD that overcomes the side effects of conventional antibody therapy.

PD-1 and TIGIT downregulation distinctly affect the effector and early memory phenotypes of CD19-targeting CAR T cells.

CD19-targeting chimeric antigen receptor (CAR) T cells have become an important therapeutic option for patients with relapsed and refractory B cell malignancies. However, a significant portion of patients still do not benefit from the therapy owing to various resistance mechanisms, including high expression of multiple inhibitory immune checkpoint receptors. Here, we report a lentiviral two-in-one CAR T approach in which two checkpoint receptors are downregulated simultaneously by a dual short hairpin RNA cassette integrated into a CAR vector. Using this system, we evaluated CD19-targeting CAR T cells in the context of four different checkpoint combinations-PD-1/TIM-3, PD-1/LAG-3, PD-1/CTLA-4, and PD-1/TIGIT-and found that CAR T cells with PD-1/TIGIT downregulation uniquely exerted synergistic antitumor effects. Importantly, functional and phenotypic analyses suggested that downregulation of PD-1 enhances short-term effector function, whereas downregulation of TIGIT is primarily responsible for maintaining a less differentiated/exhausted state, providing a potential mechanism for the observed synergy. The PD-1/TIGIT-downregulated CAR T cells generated from diffuse large B cell lymphoma patient-derived T cells also showed robust antitumor activity and significantly improved persistence in vivo. The efficacy and safety of PD-1/TIGIT-downregulated CD19-targeting CAR T cells are currently being evaluated in adult patients with relapsed or refractory large B cell lymphoma (ClinicalTrials.gov: NCT04836507).