Impact of Baseline Corticosteroid Use on the Efficacy and Safety of Upadacitinib in Patients with Ulcerative Colitis: a Post Hoc Analysis of the Phase 3 Clinical Trial Programme.

BACKGROUND AND AIMS: This post hoc analysis assessed the efficacy and safety of upadacitinib in patients with moderately to severely active ulcerative colitis stratified by corticosteroid use from the ulcerative colitis Phase 3 clinical trial programme. METHODS: Patients were randomised [1:2] to 8 weeks' placebo or upadacitinib 45 mg once daily [QD]; Week 8 responders were re-randomised [1:1:1] to 52 weeks' placebo, or upadacitinib 15 or 30 mg QD. Corticosteroid dose was kept stable during induction but tapered according to a protocol-defined schedule [or investigator discretion] during maintenance Weeks 0-8. Efficacy outcomes and exposure-adjusted treatment-emergent adverse event [TEAE] rates were assessed for induction and maintenance stratified by corticosteroid use at induction baseline. RESULTS: Overall, 377/988 [38%] patients were receiving corticosteroids at induction baseline [placebo, n = 133; upadacitinib 45 mg, n = 244] and 252 [37%] of the 681 clinical responders who entered maintenance were on corticosteroids at induction baseline [n = 84 for each treatment]. Similar proportions of patients receiving upadacitinib achieved clinical remission per Adapted Mayo Score with/without corticosteroids at Weeks 8 and 52. The total proportion of patients re-initiating corticosteroids was higher with placebo [24/84 (29%)] vs UPA 15 mg [16/81 (20%)] and 30 mg [11/81 (14%)]. During induction, patients receiving corticosteroids at baseline had higher rates of TEAEs, serious TEAEs, and serious infections vs those not receiving corticosteroids; however, TEAE rates were similar during maintenance after corticosteroid withdrawal. CONCLUSIONS: Upadacitinib is an effective steroid-sparing treatment in patients with moderately to severely active ulcerative colitis.

Differential Transgene Silencing of Myeloid-Specific Promoters in the AAVS1 Safe Harbor Locus of Induced Pluripotent Stem Cell-Derived Myeloid Cells.

Targeted integration into a genomic safe harbor, such as the AAVS1 locus on chromosome 19, promises predictable transgene expression and reduces the risk of insertional mutagenesis in the host genome. The application of gamma-retroviral long terminal repeat (LTR)-driven vectors, which semirandomly integrate into the genome, has previously caused severe adverse events in some clinical studies due to transactivation of neighboring proto-oncogenes. Consequently, the site-specific integration of a therapeutic transgene into a genomic safe harbor locus would allow stable genetic correction with a reduced risk of insertional mutagenesis. However, recent studies revealed that transgene silencing, especially in case of weaker cell type-specific promoters, can occur in the AAVS1 locus of human pluripotent stem cells (PSCs) and can impede transgene expression during differentiation. In this study, we aimed to correct p47phox deficiency, which is the second most common cause of chronic granulomatous disease, by insertion of a therapeutic p47phox transgene into the AAVS1 locus of human induced PSCs (iPSCs) using CRISPR-Cas9. We analyzed transgene expression and functional correction from three different myeloid-specific promoters (miR223, CatG/cFes, and myeloid-related protein 8 [MRP8]). Upon myeloid differentiation of corrected iPSC clones, we observed that the miR223 and CatG/cFes promoters achieved therapeutically relevant levels of p47phox expression and nicotinamide adenine dinucleotide phosphate oxidase activity, whereas the MRP8 promoter was less efficient. Analysis of the different promoters revealed high CpG methylation of the MRP8 promoter in differentiated cells, which correlated with the transgene expression data. In summary, we identified the miR223 and CatG/cFes promoters as cell type-specific promoters that allow stable transgene expression in the AAVS1 locus of iPSC-derived myeloid cells. Our findings further indicate that promoter silencing can occur in the AAVS1 safe harbor locus in differentiated hematopoietic cells and that a comparison of different promoters is necessary to achieve optimal transgene expression for therapeutic application of iPSC-derived cells.

Targeted Repair of p47-CGD in iPSCs by CRISPR/Cas9: Functional Correction without Cleavage in the Highly Homologous Pseudogenes.

Mutations in the NADPH oxidase, which is crucial for the respiratory burst in phagocytes, result in chronic granulomatous disease (CGD). The only curative treatment option for CGD patients, who suffer from severe infections, is allogeneic bone marrow transplantation. Over 90% of patients with mutations in the p47phox subunit of the oxidase complex carry the deletion c.75_76delGT (ΔGT). This frequent mutation most likely originates via gene conversion from one of the two pseudogenes NCF1B or NCF1C, which are highly homologous to NCF1 (encodes p47phox) but carry the ΔGT mutation. We applied CRISPR/Cas9 to generate patient-like p47-ΔGT iPSCs for disease modeling. To avoid unpredictable chromosomal rearrangements by CRISPR/Cas9-mediated cleavage in the pseudogenes, we developed a gene-correction approach to specifically target NCF1 but leave the pseudogenes intact. Functional assays revealed restored NADPH oxidase activity and killing of bacteria in corrected phagocytes as well as the specificity of this approach.