Beyond the stop: Oxadiazole TRIDs restore LRBA protein expression in nonsense-driven primary immunodeficiency

Nonsense mutations are among the genetic causes of LRBA (lipopolysaccharide-responsive beige-like anchor) deficiency, a rare autosomal-recessive immunodeficiency disorder. These mutations introduce premature stop codons, leading to the loss of LRBA protein expression. Following the recent market withdrawal of ataluren, the only approved translational readthrough-inducing drug (TRID), there is an urgent need for alternative therapeutic options. In this study, we investigated the efficacy of three 1,2,4-oxadiazole-based TRIDs-NV848, NV914, and NV930-using primary fibroblasts from a patient homozygous for the R1683X nonsense mutation. All compounds restored full-length LRBA protein with correct cytoplasmic localization, as confirmed by western blot and immunofluorescence, outperforming ataluren in readthrough efficiency. NV848 exhibited the strongest activity and uniquely increased LRBA mRNA levels, suggesting transcript stabilization. In contrast, NV930 and NV914 induced readthrough without stabilizing mRNA. Global proteomic profiling revealed minimal off-target effects for NV848, limited protein modulation by NV914, and widespread variations of 828 proteins by NV930, affecting pathways related to vesicular transport and mRNA splicing. However, network analysis revealed poor connectivity among differentially expressed proteins, with LRBA unrelated to any regulated cluster. These findings highlight the reported molecules as promising candidates for precision therapy in LRBA deficiency and shed light on the broader cellular impact of TRIDs.