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Preprint WatchMildAugust 27th, 2026

NLRX1 is an essential, druggable regulator of mitochondrial permeability transition

Peltier-Heap R, Frederick DW, Pickering RJ, Ghidelli-Disse S, Searle K, Barber JC, Galwey N, Wilhelm LP, Triantafilou K, Triantafilou M, Wright O, Ramachandran S, Tan Y, Xia W, Aw C, Rivers E, Lacroix Y, Reddy E, Glover RP, Brunori G, Oon P, Broom AJ, Grimsditch D, Garcia A, Robertson A, Hirano K, Browne E, Drewes G, Ganley IG, Schroder K, Ahmed M, Booty LM.

NLRX1 is the shared target of two structurally distinct brain-penetrant mitochondrial permeability transition pore inhibitors and is required for normal calcium-induced pore opening independently of cyclophilin D, with binding potency across a compound series tracking pore-inhibitory activity.

Mild contradiction

1 prior failure

One documented clinical failure (Phase 1 or 2) overlaps with the claimed mechanism.

The Claidex graph holds one NLRX1 programme. NX-13 was terminated in moderate to severe ulcerative colitis by sponsor decision rather than on a stopping rule (nx-13-nlrx1-ulcerative-colitis-nexus-phase2-sponsor-termination), so the clinical record says little about whether NLRX1 modulation works. This preprint proposes a different biology for the same gene: NLRX1 as a cyclophilin D-independent regulator of the mitochondrial permeability transition pore, identified by chemoproteomics from two distinct inhibitor chemotypes, with a lead compound that is orally bioavailable, brain-penetrant and active in a neurological injury model. The flag is mild because the tissue, the indication and the proposed mechanism all differ from the terminated gut programme. The reason to log it is that a target with one quiet clinical exit is now being advanced on a second, unrelated mechanistic rationale, and the prior programme offers no read-through in either direction.

Abstract excerpt

The molecular composition of the mitochondrial permeability transition pore (mPTP) remains contested, and several efficacious mPTP inhibitors act through undefined, cyclophilin D (CypD)-independent targets. Using two structurally distinct chemotypes of optimised, brain-penetrant mPTP inhibitors as chemical probes, we applied affinity-based chemoproteomics to identify the mitochondrial NOD-like receptor NLRX1 as their shared target. Both chemotypes bind NLRX1, and binding potency across a compound series tracks mPTP-inhibitory activity. Using CRISPR-Cas9-edited human cells and Nlrx1-/- mouse tissues, we show that NLRX1 is required for normal calcium-induced mPTP opening: its loss raises the calcium threshold for pore opening and its overexpression lowers it, independently of CypD. NLRX1 associates with postulated mPTP components, including ATP synthase and the adenine nucleotide translocase, in a compound-sensitive manner, and sustains mitochondrial protein homeostasis over longer timescales. The lead compound, GSK900, is orally bioavailable, brain-penetrant, and active in an mPTP-sensitive neurological injury model. These findings, converging with recent genetic studies, establish NLRX1 as an essential, CypD-independent regulator of mitochondrial permeability transition and provide brain-penetrant chemical tools to interrogate this biology.

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This is an automated contradiction flag, not an editorial judgment on the preprint's quality. Flags identify where the preclinical literature and the clinical failure record diverge.