ObjectiveTo evaluate risankizumab, a biological therapy that inhibits interleukin 23, in patients with active psoriatic arthritis (PsA) who have responded inadequately or are intolerant to ≥1 conventional synthetic disease-modifying antirheumatic drug (csDMARD).MethodsIn the randomised, placebo-controlled, double-blind KEEPsAKE 1 trial, 964 patients with active PsA were randomised (1:1) to receive risankizumab 150 mg or placebo at weeks 0, 4 and 16. The primary endpoint was the proportion of patients achieving ≥20% improvement in American College of Rheumatology criteria (ACR20) at week 24. Here, we report the results from the 24-week double-blind period; the open-label period with all patients receiving risankizumab is ongoing.ResultsAt week 24, a significantly greater proportion of patients receiving risankizumab achieved the primary endpoint of ACR20 (57.3% vs placebo, 33.5%; p<0.001). Significant differences were also observed for risankizumab versus placebo for the first eight ranked secondary endpoints, including skin and nail psoriasis endpoints, minimal disease activity and resolution of enthesitis and dactylitis (p<0.001). Adverse events and serious adverse events were reported at similar rates in the risankizumab and placebo groups. Serious infections were reported for 1.0% and 1.2% of patients receiving risankizumab and placebo, respectively. There was one death in the risankizumab group (urosepsis deemed unrelated to the study drug).ConclusionsRisankizumab treatment results in significantly greater improvement of signs and symptoms of PsA compared with placebo and is well tolerated in patients with active PsA who have responded inadequately or are intolerant to ≥1 csDMARD.Trial registration numberNCT03675308.

ObjectivesRisankizumab is an interleukin-23 inhibitor under study for the treatment of patients with psoriatic arthritis (PsA). The phase 3 KEEPsAKE 2 trial investigated the efficacy and safety of risankizumab versus placebo in patients with active PsA who had previous inadequate response or intolerance to ≤2 biological therapies (Bio-IR) and/or ≥1 conventional synthetic disease-modifying antirheumatic drug (csDMARD-IR). Results through week 24 are reported here.MethodsAdults with PsA who were Bio-IR and/or csDMARD-IR were randomised to receive subcutaneously administered risankizumab 150 mg or placebo at weeks 0, 4 and 16 during a 24-week, double-blind treatment period. The primary endpoint was the proportion of patients who achieved ≥20% improvement in American College of Rheumatology score (ACR20) at week 24. Secondary endpoints assessed key domains of PsA and patient-reported outcomes.ResultsA total of 444 patients (median age 53 years, range 23–84 years) were randomised to risankizumab (n=224) or placebo (n=220); 206 patients (46.5%) were Bio-IR. At week 24, a significantly greater proportion of patients receiving risankizumab achieved the primary endpoint of ACR20 (51.3% vs 26.5%, p<0.001) and all secondary endpoints (p<0.05) compared with placebo. Serious adverse events were reported for 4.0% and 5.5% of risankizumab-treated and placebo-treated patients, respectively; serious infections were reported for 0.9% and 2.3%, respectively.ConclusionTreatment with risankizumab resulted in significant improvements versus placebo in key disease outcomes and was well tolerated in patients with PsA who were Bio-IR and/or csDMARD-IR.Trial registration numberNCT03671148.

The enzyme tRNA-guanine transglycosylase (TGT, EC 2.4.2.29) catalyzes a posttranscriptional transglycosylation reaction involved in the incorporation of the modified base queuine [Q, 7-(4,5-cis-dihydroxy-2-cyclopenten-1-ylaminomethyl)-7-deazaguanine] into tRNA. Previously, the crystal structure of the TGT from Zymomonas mobilis was solved in complex with preQ(1) (the substrate for the eubacterial TGT) [Romier et al. (1996) EMBO J. 15, 2850-2857]. An aspartate residue at position 102 (position 89 in the Escherichia coli TGT) was proposed to play a nucleophilic role in an associative catalytic mechanism. Although this is an attractive and precedented mechanism, a dissociative mechanism is equally plausible. In a dissociative mechanism, aspartate 89 would provide electrostatic stabilization of an oxocarbenium ion intermediate that is formed by dissociation of guanine. To clarify the nature of the catalytic mechanism of TGT, we have generated and characterized four mutations of aspartate 89 in the E. coli TGT (alanine, asparagine, cysteine, and glutamate). All four mutant TGTs were able to noncovalently bind tRNA, but only the glutamate mutant was able to form a stable complex with the RNA substrate under denaturing conditions that was comparable to wild type. Furthermore, the glutamate mutant was the only mutant TGT that demonstrated significant activity. Kinetic parameters were determined for this enzyme and shown to be comparable to wild type, revealing that the enzyme is considerably tolerant of the positioning of the carboxylate. Under conditions of high enzyme concentrations and long time courses, the alanine, asparagine, and cysteine mutants showed very low levels (ca. 10(3)-fold lower than wild type) of activity that were linear with respect to enzyme concentration and dependent upon pH in a fashion similar to that of the wild type. However, the observed initial velocities were too low to accurately determine k(cat) and K(m) values. We hypothesize that the activity observed for these mutants is most likely derived from host strain TGT (wt) contamination. These results are most consistent with aspartate 89 acting as a nucleophile in an associative catalytic mechanism.

Objective Psoriatic arthritis (PsA) is a chronic disease with heterogeneous clinical manifestations requiring treatment options with long-term efficacy and safety. In this follow up analysis, the 52-week efficacy and safety of risankizumab 150 mg in patients with active PsA who had previous inadequate response/intolerance to one or more conventional synthetic disease modifying antirheumatic drug (csDMARD-IR) were evaluated. Methods KEEPsAKE 1 is an ongoing, global, phase 3 study with a 24-week, double-blind, placebo-controlled period (period 1) and an open-label extension period (period 2).In period 1, eligible patients were randomized 1:1 to receive subcutaneous risankizumab 150 mg or placebo at weeks 0, 4 and 16. At week 24 (period 2), all continuing patients received open-label risankizumab 150 mg every 12 weeks through week 208. Results At week 24, 57.3% of risankizumab-treated patients (N = 483) achieved ≥20% improvement in American College of Rheumatology (ACR20) criteria vs 33.5% of placebo-treated patients (N = 481; P &lt; 0.001). At week 52, 70.0% of patients who were randomized to receive continuous risankizumab therapy and 63.0% of patients who were randomized to receive placebo in period 1 and then receive risankizumab at week 24 achieved ACR20. Similar result trends were observed for other efficacy measures. Risankizumab was well tolerated through 52 weeks of treatment with a consistent safety profile from week 24 through week 52. Conclusion In patients with active PsA who were csDMARD-IR, continuous risankizumab treatment demonstrated robust long-term efficacy and was well tolerated through 52 weeks of treatment. Trial registration ClinicalTrials.gov (http://clinicaltrials.gov): KEEPsAKE1 (NCT03675308)

Background The Crohn’s Disease Activity Index (CDAI) has been criticized for being weakly correlated with bowel inflammation. We assessed correlation between Simple Endoscopic Score for Crohn’s Disease (SES-CD) and individual CDAI items stratified by disease location to better understand this relationship. Methods We pooled patient-level data from 3 placebo-controlled Crohn’s disease (CD) trials that tested adalimumab, upadacitinib, and risankizumab. Disease location was defined as ileum only, colon only, or ileocolonic based upon colonoscopy at study entry. Pearson correlation coefficients and linear regression assessed correlations between items of the CDAI and SES-CD. Results A total of 353 patients were included (20.7% ileal, 30.6% colonic, 48.7% ileocolonic disease). Crohn’s Disease Activity Index and SES-CD scores were moderately correlated (R = 0.33; P < 0.001). Among CDAI items, the strongest correlations with SES-CD were seen with very soft or liquid stool frequency (SF) and patient-reported outcome 2 (PRO2; which includes SF and abdominal pain score; both R = 0.36; P < 0.001); these correlations were numerically stronger in colonic disease (SF: R = 0.46; P < 0.001; PRO2: R = 0.44; P < 0.001) than in ileal disease (SF: R = 0.14; P = 0.23; PRO2: R = 0.21; P = 0.07), although a test for interaction was not significant. In adjusted linear regression models, the proportion of mucosa that was inflamed and the proportion of mucosa with ulceration were positively correlated, whereas the presence of strictures was inversely correlated with SF. Conclusions The SF item of the CDAI is moderately correlated with SES-CD and independently correlated with mucosal ulceration, inflammation, and strictures. Understanding why bowel inflammation as measured endoscopically does not correlate more strongly with patients’ symptoms could help develop scales that link CD pathology to patient experience.