A newly developed small-molecule inhibitor offers the first disease-modifying approach to a rare autoinflammatory syndrome, with early preclinical and clinical evidence of promise.
ROSAH syndrome (retinal dystrophy, optic nerve edema, splenomegaly, anhidrosis, and headache) is a rare, multisystem inflammatory disorder caused by pathogenic variants in ALPK1, a kinase that activates the TIFA/TRAF6/NF-κB pathway. To date, treatment has been empirical, relying on anti-cytokine therapies such as TNF, IL-1, or IL-6 inhibitors, with variable outcomes. These approaches blunt downstream inflammatory mediators but do not address the initiating genetic defect.
Fan, J., Liu, D., Ming, Z. et al. describe the identification and preclinical evaluation of DF-003, a first-in-class ALPK1 inhibitor designed to directly target the molecular driver of ROSAH. DF-003 displayed high potency against both wild-type ALPK1 (IC₅₀ = 1.5 nM) and the pathogenic ALPK1[T237M] mutant (IC₅₀ = 16 nM). In kinase profiling across 394 human kinases, DF-003 exhibited ≥860-fold selectivity, suggesting a minimal risk of off-target kinase inhibition at therapeutic concentrations.
In cell-based assays, DF-003 robustly suppressed pro-inflammatory cytokine expression, including CXCL10, TNF, and CXCL8, downstream of both wild-type and mutant ALPK1. Mechanistic experiments further support a model in which the T237M mutation sensitizes ALPK1 to activation by endogenous nucleotide sugars such as UDP-mannose, rather than conferring constitutive activity. DF-003 effectively inhibited mutant ALPK1 activity under these conditions.
To assess in vivo relevance, the authors generated a heterozygous knock-in mouse model expressing human ALPK1[T237M] alongside wild-type ALPK1. These animals recapitulated key features of ROSAH-associated neuroinflammation, including retinal microglial infiltration, astrocyte activation, and elevated chemokine expression in both retina and cortex. Oral administration of DF-003 for 10 days attenuated these phenotypes, including suppression of retinal Il6 upregulation, an encouraging finding given that IL-6 blockade has previously shown clinical benefit in ROSAH patients. Importantly, DF-003 demonstrated pharmacokinetics suitable for once-daily oral dosing and was detected in both retina and brain, confirming its ability to cross relevant tissue barriers.
While the mouse model did not fully recapitulate all aspects of the human syndrome the reversal of inflammatory signatures by DF-003 offers compelling preclinical support for its therapeutic potential. Limitations include the uncertain translatability of murine inflammatory readouts to human retinal pathology and the need to monitor for potential immunosuppression in clinical settings.
With the initiation of a Phase 1b clinical trial in adults with ROSAH syndrome (NCT06395285), DF-003 represents the first targeted therapeutic strategy aimed at the root cause of this disease. If successful, it could not only transform treatment for ROSAH but also provide a valuable tool to interrogate ALPK1-driven inflammatory biology more broadly.
Read the full article here: Fan, J., Liu, D., Ming, Z. et al. Discovery of a selective alpha-kinase 1 inhibitor for the rare genetic disease ROSAH syndrome. Nat Commun 16, 8251 (2025).