IF a novel brain-penetrant, non-nucleotide cGAS inhibitor bearing an N-(4-(spiro[3.3]heptan-2-yl)pyridin-2-yl)acetamide scaffold — computationally optimized for CNS exposure (CNS MPO score ≥4.0, predicted P-gp non-substrate, tPSA <60 Ų, logP 2.0–4.0, MW <400 Da for evolved lead), administered via oral gavage at a dose range informed by in vitro IC₅₀ values against recombinant human cGAS (residues 150–522) — is administered to aged (22–24 month) male and female C57BL/6J mice carrying accumulated chronic neuroinflammatory damage,

THEN a measurable reversal of established CNS cGAS-STING pathway hyperactivation will be observed — specifically: ≥40% reduction in brain-resident IFN-β, CXCL10, and IL-6 protein levels by multiplex ELISA; ≥30% reduction in IBA-1⁺ microglial density and shift from amoeboid to ramified morphology by immunohistochemistry; and ≥20% improvement in spatial memory index in Morris Water Maze versus aged vehicle controls — within 8 weeks of continuous treatment,

BECAUSE the following causal chain is supported:

1. Aged post-mitotic neurons, astrocytes, and microglia accumulate cytosolic DNA species — including nuclear envelope rupture-derived chromatin fragments, ruptured micronuclei, and mitochondrial DNA (mtDNA) escapees — that constitutively activate the cGAS catalytic domain (residues 150–522, ATP/GTP binding site) in a manner that is independent of new DNA damage; this accumulation is a consequence of already-accrued damage that persists even after upstream insults are controlled (finding from literature task output describing cGAS as the cytosolic dsDNA sensor activating the type I interferon pathway). [SPECULATIVE link: the rate of cytosolic DNA accumulation in aged CNS tissue likely exceeds lysosomal DNase II clearance capacity, creating a self-sustaining activation state.]

2. Chronic cGAS-STING signalling in aged brain tissue drives sustained type I interferon production and downstream NF-κB activation, establishing a neuroinflammatory "set point" that cannot be resolved by simply removing the DNA source — the signalling cascade itself represents accumulated functional damage requiring direct pharmacological reversal (literature task output: cGAS synthesizes the second messenger cGAMP, which then activates STING and downstream interferon regulatory factors).

3. Current clinical cGAS inhibitor chemotypes (fused heterocycles and pyrazolopyrimidines) have physicochemical profiles that preclude adequate BBB penetration and suffer from P-gp and BCRP-mediated efflux, leaving the CNS compartment pharmacologically underserved (literature task output: ADMET profiling using CNS MPO algorithm by Wager et al. and BOILED-Egg model by Daina et al., confirming that classical nucleotide-mimicking scaffolds are poor CNS candidates).

4. The computationally derived spiro[3.3]heptane-containing non-nucleotide scaffold — identified by fragment screening against the AF-Q8N884-F1 AlphaFold model catalytic pocket after SMARTS-based e...

SENS category: LysoSENS