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Background Predictions based on patient-derived materials of CFTR modulators efficacy have been performed lately in patient-derived cells, extending FDA-approved drugs for CF patients harboring rare variants. Here we developed intestinal organoids from subjects carrying S737F- and T465N-CFTR in trans with null alleles to evaluate their functional impact on CFTR protein function and their restoration upon CFTR modulator treatment. The characterization of S737F-CFTR was performed in two subjects recently assessed in nasal epithelial cells but not in colonoids. Results Our functional analysis (Ussing chamber) confirmed that S737F-CFTR is a mild variant with residual function as investigated in colonoids of patients with S737F/Dele22-24 and S737F/W1282X genotypes. An increase of current upon Elexacaftor/Tezacaftor/Ivacaftor (ETI) treatment was recorded for the former genotype. T465N is a poorly characterized missense variant that strongly impacts CFTR function, as almost no CFTR-mediated anion secretion was registered for T465N/Q39X colonoids. ETI treatment substantially improved CFTR-mediated anion secretion and increased the rescue of mature CFTR expression compared to either untreated colonoids or to dual CFTR modulator therapies. Conclusions Our study confirms the presence of a residual function of the S737F variant and its limited response to CFTR modulators while predicting for the first time the potential clinical benefit of Trikafta® for patients carrying the rare T465N variant.

Shwachman-Diamond syndrome (SDS) is characterized by exocrine pancreatic insufficiency, neutropenia, and a high risk of myeloid malignancy. Most patients with SDS harbor nonsense mutations in Shwachman-Bodian-Diamond syndrome gene ( SBDS) , which encodes a ribosome assembly factor. We investigated the translational read-through effect of ataluren in three patients with SDS undergoing a compassionate use program for twelve months. The primary and secondary endpoints were restoring SBDS protein levels in hematopoietic cells and improving myelopoiesis, respectively. SBDS synthesis increased in hematopoietic cells, whereas the bone marrow showed improved cellularity with the maturation of myeloid progenitors. In parallel, absolute neutrophil count was improved in two out of three patients, whereas platelet count increased in all recruited patients. Ataluren treatment normalized mTOR phosphorylation in peripheral blood monocytes and lymphocytes, suggesting a reduction of ribosomal stress. The exocrine pancreatic function also improved. Although the reduced sample size may represent a major limitation of this work, our findings strongly encourages the further clinical development of ataluren to treat SDS. Ataluren restored SBDS protein synthesis in three patients with Shwachman-Diamond syndrome, improving bone marrow cellularity and pancreatic function without side effects, highlighting its potential as therapeutic option for this genetic disease.

Background Elexacaftor-tezacaftor-ivacaftor (ETI) improves clinical outcomes in people with Cystic Fibrosis (pwCF), with possible anti-inflammatory properties. However, the molecular mechanisms underlying these effects remain unclear. This study investigates ETI’s anti-inflammatory and immunomodulatory activity, focusing on essential signaling pathways. Methods Forty-nine pwCF were followed for 24 months. PwCF underwent clinical and pulmonary function assessment along with sweat test chloride measurement. Blood samples were analyzed for red and white blood cell counts and C-reactive protein (CRP). Plasma cytokines were quantified and phospho-kinase arrays and western blotting were used to assess protein phosphorylation in peripheral blood mononuclear cells (PBMC) from pwCF and healthy controls, pre- and post-ETI. Gene expression was evaluated in patient-derived PBMC and CF bronchial epithelial cells in vitro. Results ETI treatment significantly improved percent-predicted forced expiratory volume in 1 s (ppFEV1) and reduced intravenous antibiotic use. Inflammatory markers (including CRP) and circulating leukocytes decreased, especially lymphocytes and monocytes. Six of 27 pro-inflammatory cytokines were significantly downregulated. ETI strongly inhibited Signal Transducer and Activator of Transcription 5 (STAT5) phosphorylation in PBMC and CF epithelial cells, both in vivo and in vitro. This correlated with reduced interleukin IL-6, IL-8, and TNF-α mRNA levels. Pharmacological inhibition of JAK/STAT mimicked ETI effects on cytokine expression, supporting STAT5 as an important player involved in CF chronic inflammation. Conclusion Long-term ETI treatment confirms clinical benefits and exerts measurable immunomodulatory effects, partially via inhibition of JAK/STAT signaling. These findings support its broader impact beyond CFTR correction. Further studies are warranted to explore long-term immunological outcomes, especially in younger patients initiating early therapy.

Fanconi anemia (FA) is a rare inherited bone marrow failure syndrome characterized by genomic instability, mitochondrial dysfunction, and oxidative stress. While the therapeutic potential of ataluren, a translational readthrough-inducing drug, has been investigated in FA cells carrying nonsense mutations, its broader metabolic impact remains unclear. Here, we demonstrate that ataluren (tested at 2.5, 5, and 10 μM) modulates cellular energy metabolism and redox homeostasis in FA lymphoblasts harboring either nonsense or missense mutations in the FANCA gene. At low doses (2.5 μM for 72 h), ataluren improved the ATP/AMP ratio, enhanced oxidative phosphorylation efficiency, and reduced lipid peroxidation and oxidative DNA damage. These effects were independent of mutation type and were not associated with compensatory glycolysis, as lactate dehydrogenase activity remained unchanged. Strikingly, ataluren restored the P/O ratio under pyruvate/malate-driven respiration to near-normal values, indicating improved coupling between oxygen consumption and ATP synthesis. Mechanistically, ataluren reduced DRP1 protein levels and attenuated mTOR-S6 signaling, suggesting that mitochondrial dynamics and bioenergetic efficiency are modulated via the mTOR–DRP1 axis. Additionally, ataluren lowered IMPDH activity, contributing to reduced cell proliferation and DNA damage without impairing cellular energy status. Notably, these beneficial effects persisted under immune stimulation, where ataluren mitigated the metabolic and oxidative burden imposed by lymphocyte activation. Our findings unveil a pleiotropic role for ataluren that extends beyond its canonical readthrough activity, highlighting its potential as a metabolic modulator for FA and possibly other DNA repair–deficient disorders.

Fanconi anemia (FA) is caused by mutations affecting FANC genes involved in DNA repair, with nearly 20% of FA patients harboring nonsense mutations. Ataluren (PTC124) is a translational read-through-inducing drug (TRID) already approved in Europe that has a well-established safety profile even in pediatric patients. Amlexanox, an anti-inflammatory drug, also promotes read-through of premature stop codons caused by nonsense mutations. We compared ataluren and amlexanox in rescuing FANCA, FANCC and FANCF protein synthesis in lymphoblastoid cell lines and fibroblasts obtained from FA patients with nonsense mutations. While ataluren restored all FANC protein levels, amlexanox was partially effective only on FANCA. Notably, the rescue of FANC proteins resulted in a significant downregulation of p53. Moreover, unlike amlexanox, ataluren remarkably improved cell viability and reduced chromosomal aberrations upon exposure to genotoxic compounds. Amlexanox primarily reduced the signal transducer and activator of transcription 2 (STAT2) phosphorylation. Furthermore, FANCA -mutated fibroblasts exhibited a higher frequency of micronuclei formation as well as lower lamin B1 expression compared to their gene-edited counterpart re-expressing wild-type FANCA . Interestingly, ataluren significantly limited the generation of micronuclei in nonsense-mutated primary FANCC fibroblasts, restoring lamin B1 expression. This study represents a milestone of drug development for FA as it paves the way for clinical development of TRIDs, indicating ataluren as a promising approach to address the genetic instability and reduce the risk of malignant transformation in FA cells. Moreover, these results highlight the importance of a reliable experimental pipeline to assess whether minimal protein rescue via translational read-through can yield meaningful phenotypic rescue.

Despite the promising results of new CFTR targeting drugs designed for the recovery of F508del- and class III variants activity, none of them have been approved for individuals with selected rare mutations, because uncharacterized CFTR variants lack information associated with the ability of these compounds in recovering their molecular defects. Here we used both rectal organoids (colonoids) and primary nasal brushed cells (hNEC) derived from a CF patient homozygous for A559T (c.1675G>A) variant to evaluate the responsiveness of this pathogenic variant to available CFTR targeted drugs that include VX-770, VX-809, VX-661 and VX-661 combined with VX-445. A559T is a rare mutation, found in African-Americans people with CF (PwCF) with only 85 patients registered in the CFTR2 database. At present, there is no treatment approved by FDA (U.S. Food and Drug Administration) for this genotype. Short-circuit current (Isc) measurements indicate that A559T-CFTR presents a minimal function. The acute addition of VX-770 following CFTR activation by forskolin had no significant increment of baseline level of anion transport in both colonoids and nasal cells. However, the combined treatment, VX-661-VX-445, significantly increases the chloride secretion in A559T-colonoids monolayers and hNEC, reaching approximately 10% of WT-CFTR function. These results were confirmed by forskolin-induced swelling assay and by western blotting in rectal organoids. Overall, our data show a relevant response to VX-661-VX-445 in rectal organoids and hNEC with CFTR genotype A559T/A559T. This could provide a strong rationale for treating patients carrying this variant with VX-661-VX-445-VX-770 combination.

Despite the promising results of new CFTR targeting drugs designed for the recovery of F508del- and class III variants activity, none of them have been approved for individuals with selected rare mutations, because uncharacterized CFTR variants lack information associated with the ability of these compounds in recovering their molecular defects. Here we used both rectal organoids (colonoids) and primary nasal brushed cells (hNEC) derived from a CF patient homozygous for A559T (c.1675G>A) variant to evaluate the responsiveness of this pathogenic variant to available CFTR targeted drugs that include VX-770, VX-809, VX-661 and VX-661 combined with VX-445. A559T is a rare mutation, found in African-Americans people with CF (PwCF) with only 85 patients registered in the CFTR2 database. At present, there is no treatment approved by FDA (U.S. Food and Drug Administration) for this genotype. Short-circuit current (Isc) measurements indicate that A559T-CFTR presents a minimal function. The acute addition of VX-770 following CFTR activation by forskolin had no significant increment of baseline level of anion transport in both colonoids and nasal cells. However, the combined treatment, VX-661-VX-445, significantly increases the chloride secretion in A559T-colonoids monolayers and hNEC, reaching approximately 10% of WT-CFTR function. These results were confirmed by forskolin-induced swelling assay and by western blotting in rectal organoids. Overall, our data show a relevant response to VX-661-VX-445 in rectal organoids and hNEC with CFTR genotype A559T/A559T. This could provide a strong rationale for treating patients carrying this variant with VX-661-VX-445-VX-770 combination.

Shwachman-Diamond syndrome (SDS) is a ribosomopathy characterized by neutropenia, pancreatic insufficiency, skeletal defects, and predisposition to leukemia. Most cases result from biallelic mutations that impairing 80S ribosome and polysome assembly. In yeast lacking (the ortholog), growth slows dramatically and the p38 ortholog Hog1 signaling is elevated by multiple types of stress. SBDS-deficient HeLa cells exhibited reduced proliferation and slowed cell cycling. The p38 kinase was constitutively activated in mutants and SDS patient-derived blood cells. Because ZAKα detects ribosome dysfunction, its activation links ribosomal defects to stress kinase pathways in SDS. Suppressing p38α or its upstream activator ZAKα restored cell growth and reduced stress signaling. These findings reveal an evolutionarily conserved-independent mechanism via p38 drives SDS pathophysiology and identifies stress kinases as potential therapeutic targets for ribosomal dysfunction.