Safety and efficacy of linaclotide in children aged 2-5 years with functional constipation: Phase 2, randomized study.

OBJECTIVES: Linaclotide, a guanylate cyclase-C agonist, was recently approved in the United States for the treatment of children 6-17 years of age with functional constipation (FC). This study evaluated the dose-response, safety, and efficacy of 4 weeks of linaclotide compared with placebo in children 2-5 years of age with FC. METHODS: In this phase 2, randomized, double-blind, placebo-controlled, multidose study, 35 children with FC (based on Rome III criteria) were randomized 3:1 to receive linaclotide (18, 36, or 72 µg, for groups 1, 2, and 3, respectively) and 5:1 to receive linaclotide 9, 18, 36, or 72 µg (group 4), or matching placebo. Key endpoints were the changes from baseline in overall spontaneous bowel movement (SBM) frequency (SBMs/week), stool consistency, and straining, as well as the proportion of days with fecal incontinence during the study intervention period. Adverse events (AEs) were recorded. RESULTS: Of the randomized patients, 34 (97.1%) completed the treatment period and 33 (94.3%) completed the posttreatment period. Mean change from baseline over the treatment period for three of the four key efficacy endpoints showed greater improvement in the linaclotide 72 µg group versus placebo. A dose-response trend was seen for stool consistency in patients receiving linaclotide. Four patients randomized to linaclotide experienced treatment-emergent AEs, one of which was treatment-related (mild diarrhea). All AEs were mild or moderate and none were severe. CONCLUSIONS: Linaclotide was well tolerated in this pediatric population and an efficacy trend was seen with linaclotide 72 µg versus placebo.

Upadacitinib as induction and maintenance therapy for moderately to severely active ulcerative colitis: results from three phase 3, multicentre, double-blind, randomised trials.

BACKGROUND: There is a great unmet need for advanced therapies that provide rapid, robust, and sustained disease control for patients with ulcerative colitis. We assessed the efficacy and safety of upadacitinib, an oral selective Janus kinase 1 inhibitor, as induction and maintenance therapy in patients with moderately to severely active ulcerative colitis. METHODS: This phase 3, multicentre, randomised, double-blind, placebo-controlled clinical programme consisted of two replicate induction studies (U-ACHIEVE induction [UC1] and U-ACCOMPLISH [UC2]) and a single maintenance study (U-ACHIEVE maintenance [UC3]). The studies were conducted across Europe, North and South America, Australasia, Africa, and the Asia-Pacific region at 199 clinical centres in 39 countries (UC1), 204 clinical centres in 40 countries (UC2), and 195 clinical centres in 35 countries (UC3). Patients aged 16-75 years with moderately to severely active ulcerative colitis (Adapted Mayo score 5-9; endoscopic subscore 2 or 3) for at least 90 days were randomly assigned (2:1) to oral upadacitinib 45 mg once daily or placebo for 8 weeks (induction studies). Patients who achieved clinical response following 8-week upadacitinib induction were re-randomly assigned (1:1:1) to upadacitinib 15 mg, upadacitinib 30 mg, or placebo for 52 weeks (maintenance study). All patients were randomly assigned using web-based interactive response technology. The primary endpoints were clinical remission per Adapted Mayo score at week 8 (induction) and week 52 (maintenance). The efficacy analyses in the two induction studies were based on the intent-to-treat population, which included all randomised patients who received at least one dose of treatment. In the maintenance study, the primary efficacy analyses reported in this manuscript were based on the first 450 (planned) clinical responders to 8-week induction therapy with upadacitinib 45 mg once daily. The safety analysis population in the induction studies consisted of all randomised patients who received at least one dose of treatment; in the maintenance study, this population included all patients who received at least one dose of treatment as part of the primary analysis population. These studies are registered at ClinicalTrials.gov, NCT02819635 (U-ACHIEVE) and NCT03653026 (U-ACCOMPLISH). FINDINGS: Between Oct 23, 2018, and Sept 7, 2020, 474 patients were randomly assigned to upadacitinib 45 mg once daily (n=319) or placebo (n=155) in UC1. Between Dec 6, 2018, and Jan 14, 2021, 522 patients were randomly assigned to upadacitinib 45 mg once daily (n=345) or placebo (n=177) in UC2. In UC3, a total of 451 patients (21 from the phase 2b study, 278 from UC1, and 152 from UC2) who achieved a clinical response after 8 weeks of upadacitinib induction treatment were randomly assigned again to upadacitinib 15 mg (n=148), upadacitinib 30 mg (n=154), and placebo (n=149) in the primary analysis population. Statistically significantly more patients achieved clinical remission with upadacitinib 45 mg (83 [26%] of 319 patients in UC1 and 114 [34%] of 341 patients in UC2) than in the placebo group (seven [5%] of 154 patients in UC1 and seven [4%] of 174 patients; p<0·0001; adjusted treatment difference 21·6% [95% CI 15·8-27·4] for UC1 and 29·0% [23·2-34·7] for UC2). In the maintenance study, clinical remission was achieved by statistically significantly more patients receiving upadacitinib (15 mg 63 [42%] of 148; 30 mg 80 [52%] of 154) than those receiving placebo (18 [12%] of 149; p<0·0001; adjusted treatment difference 30·7% [21·7-39·8] for upadacitinib 15 mg vs placebo and 39·0% [29·7-48·2] for upadacitinib 30 mg vs placebo). The most commonly reported adverse events in UC1 were nasopharyngitis (15 [5%] of 319 in the upadacitinib 45 mg group vs six [4%] of 155 in the placebo group), creatine phosphokinase elevation (15 [4%] vs three [2%]), and acne (15 [5%] vs one [1%]). In UC2, the most frequently reported adverse event was acne (24 [7%] of 344 in the upadacitinib 45 mg group vs three [2%] of 177 in the placebo group). In both induction studies, serious adverse events and adverse events leading to discontinuation of treatment were less frequent in the upadacitinib 45 mg group than in the placebo group (serious adverse events eight [3%] vs nine (6%) in UC1 and 11 [3%] vs eight [5%] in UC2; adverse events leading to discontinuation six [2%] vs 14 [9%] in UC1 and six [2%] vs nine [5%] in UC2). In UC3, the most frequently reported adverse events (≥5%) were worsening of ulcerative colitis (19 [13%] of 148 in the upadacitinib 15 mg group vs 11 [7%] of 154 in the upadacitinib 30 mg group vs 45 [30%] of 149 in the placebo group), nasopharyngitis (18 [12%] vs 22 [14%] vs 15 [10%]), creatine phosphokinase elevation (nine [6%] vs 13 [8%] vs three [2%]), arthralgia (nine [6%] vs five [3%] vs 15 [10%]), and upper respiratory tract infection (seven [5%] vs nine [6%] vs six [4%]). The proportion of serious adverse events (ten [7%] vs nine [6%] vs 19 [13%]) and adverse events leading to discontinuation (six [4%] vs ten [6%] vs 17 [11%]) was lower in both upadacitinib groups than in the placebo group. Events of cancer, adjudicated major adverse cardiac events, or venous thromboembolism were reported infrequently. There were no treatment-related deaths. INTERPRETATION: Upadacitinib demonstrated a positive efficacy and safety profile and could be an effective treatment option for patients with moderately to severely active ulcerative colitis. FUNDING: AbbVie.

Higher vs Standard Adalimumab Induction and Maintenance Dosing Regimens for Treatment of Ulcerative Colitis: SERENE UC Trial Results.

BACKGROUND & AIMS: SERENE UC (Study of a Novel Approach to Induction and Maintenance Dosing With Adalimumab in Patients With Moderate to Severe Ulcerative Colitis) evaluated the efficacy of higher adalimumab induction and maintenance dose regimens in patients with ulcerative colitis. METHODS: This phase 3, double-blind, randomized trial included induction and maintenance studies, with a main study (ex-Japan) and Japan substudy. Eligible patients (18-75 years, full Mayo score 6-12, centrally read endoscopy subscore 2-3) were randomized 3:2 to higher induction regimen (adalimumab 160 mg at weeks 0, 1, 2, and 3) or standard induction regimen (160 mg at week 0 and 80 mg at week 2); all received 40 mg at weeks 4 and 6. At week 8, all patients were rerandomized 2:2:1 (main study) to 40 mg every week (ew), 40 mg every other week (eow), or exploratory therapeutic drug monitoring; or 1:1 (Japan substudy) to 40 mg ew or 40 mg eow maintenance regimens. RESULTS: In the main study, 13.3% vs 10.9% of patients receiving the higher induction regimen vs standard induction regimen achieved clinical remission (full Mayo score ≤2 with no subscore >1) at week 8 (induction primary end point; P = .265); among week-8 responders, 39.5% vs 29.0% receiving 40 mg ew vs 40 mg eow achieved clinical remission at week 52 (maintenance primary end point; P = .069). In the integrated (main + Japan) population, 41.1% vs 30.1% of week-8 responders receiving 40 mg ew vs 40 mg eow achieved clinical remission at week 52 (nominal P = .045). Safety profiles were comparable between dosing regimens. CONCLUSION: Although primary end points were not met, a >10% absolute difference in clinical remission was demonstrated with higher adalimumab maintenance dosing. Higher dosing regimens were generally well tolerated and consistent with the known safety profile of adalimumab in ulcerative colitis. CLINICALTRIALS: gov, Number: NCT002209456.

Pooled Resistance Analysis in Patients with Hepatitis C Virus Genotype 1 to 6 Infection Treated with Glecaprevir-Pibrentasvir in Phase 2 and 3 Clinical Trials.

Over 2,200 patients infected with hepatitis C virus (HCV) genotypes (GT) 1 to 6, with or without cirrhosis, who were treatment naive or experienced to interferon, ribavirin, and/or sofosbuvir were treated with glecaprevir/pibrentasvir for 8, 12, or 16 weeks in eight registrational phase 2 and 3 clinical studies. High rates of sustained virologic response at 12 weeks postdosing (SVR12) were achieved with a <1% virologic failure (VF) rate. The prevalence of baseline polymorphisms (BPs) in NS3 at amino acid position 155 or 168 was low (<3%) in patients infected with GT1, GT2, GT3, GT4, and GT6, while 41.9% of the GT5-infected patients had NS3-D168E; BPs were not detected at position 156 in NS3. The prevalence of NS5A-BPs was high across genotypes, driven by common polymorphisms at amino acid position 30 or 31 in GT2, 58 in GT4, and 28 in GT6. The prevalence of NS5A T/Y93 polymorphisms was 5.5% in GT1, 4.9% in GT3, and 12.5% in GT6. Consistent with the activity of glecaprevir and pibrentasvir against most amino acid polymorphisms in vitro, BPs in NS3 and/or NS5A did not have an impact on treatment outcome for patients infected with GT1 to GT6, with the exception of treatment-experienced GT3-infected patients treated for 12 weeks, for whom a 16-week regimen of glecaprevir/pibrentasvir was required to achieve SVR12 rates of ≥95%. Among the 22 patients experiencing VF, treatment-emergent substitutions were detected in NS3 in 50% of patients and in NS5A in 82% of patients, frequently as a combination of substitutions that conferred resistance to glecaprevir and/or pibrentasvir. The glecaprevir/pibrentasvir regimen, when the recommended durations are used, allows for a pan-genotypic treatment option without the need for baseline resistance testing.

Integrated Resistance Analysis of CERTAIN-1 and CERTAIN-2 Studies in Hepatitis C Virus-Infected Patients Receiving Glecaprevir and Pibrentasvir in Japan.

Glecaprevir and pibrentasvir are hepatitis C virus (HCV) pangenotypic inhibitors targeting NS3/4A protease and NS5A, respectively. This once-daily, fixed-dose combination regimen demonstrated high sustained virologic response 12 weeks postdosing (SVR12) rates in CERTAIN-1 and CERTAIN-2 studies in Japanese HCV-infected patients, with a low virologic failure rate (1.2%). There were no virologic failures among direct-acting antiviral (DAA)-treatment-naive genotype 1a (GT1a) (n = 4)-, GT1b (n = 128)-, and GT2 (n = 97)-infected noncirrhotic patients treated for 8 weeks or among GT1b (n = 38)- or GT2 (n = 20)-infected patients with compensated cirrhosis treated for 12 weeks. Two of 33 DAA-experienced and 2 of 12 GT3-infected patients treated for 12 weeks experienced virologic failure. Pooled resistance analysis, grouped by HCV subtype, treatment duration, prior treatment experience, and cirrhosis status, was conducted. Among DAA-naive GT1b-infected patients, the baseline prevalence of NS3-D168E was 1.2%, that of NS5A-L31M was 3.6%, and that of NS5A-Y93H was 17.6%. Baseline polymorphisms in NS3 or NS5A were less prevalent in GT2, with the exception of the common L/M31 polymorphism in NS5A. Among DAA-experienced GT1b-infected patients (30/32 daclatasvir plus asunaprevir-experienced patients), the baseline prevalence of NS3-D168E/T/V was 48.4%, that of NS5A-L31F/I/M/V was 81.3%, that of the NS5A P32deletion was 6.3%, and that of NS5A-Y93H was 59.4%. Common baseline polymorphisms in NS3 and/or NS5A had no impact on treatment outcomes in GT1- and GT2-infected patients; the impact on GT3-infected patients could not be assessed due to the enrollment of patients infected with diverse subtypes and the limited number of patients. The glecaprevir-pibrentasvir combination regimen allows a simplified treatment option without the need for HCV subtyping or baseline resistance testing for DAA-naive GT1- or GT2-infected patients. (The CERTAIN-1 and CERTAIN-2 studies have been registered at ClinicalTrials.gov under identifiers NCT02707952 and NCT02723084, respectively.).

An interferon-free antiviral regimen for HCV after liver transplantation.

BACKGROUND: Hepatitis C virus (HCV) infection is the leading indication for liver transplantation worldwide, and interferon-containing regimens are associated with low response rates owing to treatment-limiting toxic effects in immunosuppressed liver-transplant recipients. We evaluated the interferon-free regimen of the NS5A inhibitor ombitasvir coformulated with the ritonavir-boosted protease inhibitor ABT-450 (ABT-450/r), the nonnucleoside NS5B polymerase inhibitor dasabuvir, and ribavirin in liver-transplant recipients with recurrent HCV genotype 1 infection. METHODS: We enrolled 34 liver-transplant recipients with no fibrosis or mild fibrosis, who received ombitasvir-ABT-450/r (at a once-daily dose of 25 mg of ombitasvir, 150 mg of ABT-450, and 100 mg of ritonavir), dasabuvir (250 mg twice daily), and ribavirin for 24 weeks. Selection of the initial ribavirin dose and subsequent dose modifications for anemia were at the investigator's discretion. The primary efficacy end point was a sustained virologic response 12 weeks after the end of treatment. RESULTS: Of the 34 study participants, 33 had a sustained virologic response at post-treatment weeks 12 and 24, for a rate of 97% (95% confidence interval, 85 to 100). The most common adverse events were fatigue, headache, and cough. Five patients (15%) required erythropoietin; no patient required blood transfusion. One patient discontinued the study drugs owing to adverse events after week 18 but had a sustained virologic response. Blood levels of calcineurin inhibitors were monitored, and dosages were modified to maintain therapeutic levels; no episode of graft rejection was observed during the study. CONCLUSIONS: Treatment with the multitargeted regimen of ombitasvir-ABT-450/r and dasabuvir with ribavirin was associated with a low rate of serious adverse events and a high rate of sustained virologic response among liver-transplant recipients with recurrent HCV genotype 1 infection, a historically difficult-to-treat population. (Funded by AbbVie; CORAL-I ClinicalTrials.gov number, NCT01782495.).

Phase 2b trial of interferon-free therapy for hepatitis C virus genotype 1.

BACKGROUND: An interferon-free combination of the protease inhibitor ABT-450 with ritonavir (ABT-450/r), the nonnucleoside polymerase inhibitor ABT-333, and ribavirin showed efficacy against the hepatitis C virus (HCV) in a pilot study involving patients with HCV genotype 1 infection. The addition of another potent agent, the NS5A inhibitor ABT-267, may improve efficacy, especially in difficult-to-treat patients. This study was designed to evaluate multiple regimens of direct-acting antiviral agents and ribavirin in patients with HCV genotype 1 infection who had not received therapy previously or who had no response to prior therapy with pegylated interferon and ribavirin. METHODS: In this phase 2b, open-label study with 14 treatment subgroups, 571 patients without cirrhosis who had not received treatment previously or who had not had a response to prior therapy were randomly assigned to a regimen of ABT-450/r, combined with ABT-267 or ABT-333 or both, for 8, 12, or 24 weeks and received at least one dose of therapy. All the subgroups but 1 also received ribavirin (dose determined according to body weight). The primary end point was sustained virologic response at 24 weeks after the end of treatment. The primary efficacy analysis compared rates between previously untreated patients who received three direct-acting antiviral agents and ribavirin for 8 weeks and those who received the same therapy for 12 weeks. RESULTS: Among previously untreated patients who received three direct-acting antiviral agents (with the ABT-450/r dose administered as 150 mg of ABT-450 and 100 mg of ritonavir) plus ribavirin, the rate of sustained virologic response at 24 weeks after treatment was 88% among those who received the therapy for 8 weeks and 95% among those who received the therapy for 12 weeks (difference, -7 percentage points; 95% confidence interval, -19 to 5; P=0.24). The rates of sustained virologic response across all treatment subgroups ranged from 83 to 100%. The most frequent adverse events were fatigue, headache, nausea, and insomnia. Eight patients (1%) discontinued treatment owing to adverse events. CONCLUSIONS: In this phase 2b study, all-oral regimens of antiviral agents and ribavirin were effective both in patients with HCV genotype 1 infection who had not received therapy previously and in those who had not had a response to prior therapy. (Funded by AbbVie; ClinicalTrials.gov number, NCT01464827.).

ABT-450/r-ombitasvir and dasabuvir with or without ribavirin for HCV.

BACKGROUND: The interferon-free regimen of ABT-450 with ritonavir (ABT-450/r), ombitasvir, and dasabuvir with or without ribavirin has shown efficacy in inducing a sustained virologic response in a phase 2 study involving patients with hepatitis C virus (HCV) genotype 1 infection. We conducted two phase 3 trials to examine the efficacy and safety of this regimen in previously untreated patients with HCV genotype 1 infection and no cirrhosis. METHODS: We randomly assigned 419 patients with HCV genotype 1b infection (PEARL-III study) and 305 patients with genotype 1a infection (PEARL-IV study) to 12 weeks of ABT-450/r-ombitasvir (at a once-daily dose of 150 mg of ABT-450, 100 mg of ritonavir, and 25 mg of ombitasvir), dasabuvir (250 mg twice daily), and ribavirin administered according to body weight or to matching placebo for ribavirin. The primary efficacy end point was a sustained virologic response (an HCV RNA level of <25 IU per milliliter) 12 weeks after the end of treatment. RESULTS: The study regimen resulted in high rates of sustained virologic response among patients with HCV genotype 1b infection (99.5% with ribavirin and 99.0% without ribavirin) and among those with genotype 1a infection (97.0% and 90.2%, respectively). Of patients with genotype 1b infection, 1 had virologic failure, and 2 did not have data available at post-treatment week 12. Among patients with genotype 1a infection, the rate of virologic failure was higher in the ribavirin-free group than in the ribavirin group (7.8% vs. 2.0%). In both studies, decreases in the hemoglobin level were significantly more common in patients receiving ribavirin. Two patients (0.3%) discontinued the study drugs owing to adverse events. The most common adverse events were fatigue, headache, and nausea. CONCLUSIONS: Twelve weeks of treatment with ABT-450/r-ombitasvir and dasabuvir without ribavirin was associated with high rates of sustained virologic response among previously untreated patients with HCV genotype 1 infection. Rates of virologic failure were higher without ribavirin than with ribavirin among patients with genotype 1a infection but not among those with genotype 1b infection. (Funded by AbbVie; PEARL-III and PEARL-IV ClinicalTrials.gov numbers, NCT01767116 and NCT01833533.).

Low relapse rate leads to high concordance of sustained virologic response (SVR) at 12 weeks with SVR at 24 weeks after treatment with ABT-450/ritonavir, ombitasvir, and dasabuvir plus ribavirin in subjects with chronic hepatitis C virus genotype 1 infection in the AVIATOR study.

In 247 subjects with hepatitis C virus genotype 1 infection treated with the interferon-free regimen of ABT-450/ritonavir, ombitasvir, and dasabuvir plus ribavirin, concordance of a sustained virologic response at 12 and 24 weeks supports the use of the earlier time point as a primary efficacy endpoint for trials of this interferon-free regimen.

Resistance analysis of baseline and treatment-emergent variants in hepatitis C virus genotype 1 in the AVIATOR study with paritaprevir-ritonavir, ombitasvir, and dasabuvir.

AVIATOR, a phase 2 clinical trial, evaluated ritonavir-boosted paritaprevir (a protease inhibitor), ombitasvir (an NS5A inhibitor), and dasabuvir (a nonnucleoside polymerase inhibitor) (the three-drug [3D] regimen) with or without ribavirin (RBV) for 8, 12, or 24 weeks in 406 HCV genotype 1 (GT1)-infected patients. The rate of sustained virologic response 24 weeks after treatment ranged from 88% to 100% across the arms of the 3D regimen with or without RBV; 20 GT1a-infected patients and 1 GT1b-infected patient experienced virologic failure (5.2%). Baseline resistance-conferring variants in NS3 were rare. M28V in GT1a and Y93H in GT1b were the most prevalent preexisting variants in NS5A, and C316N in GT1b and S556G in both GT1a and GT1b were the most prevalent variants in NS5B. Interestingly, all the GT1a sequences encoding M28V in NS5A were from the United States, while GT1b sequences encoding C316N and S556G in NS5B were predominant in the European Union. Variants preexisting at baseline had no significant impact on treatment outcome. The most prevalent treatment-emergent resistance-associated variants (RAVs) in GT1a were R155K and D168V in NS3, M28T and Q30R in NS5A, and S556G in NS5B. The single GT1b-infected patient experiencing virologic failure had no RAVs in any target. A paritaprevir-ritonavir dose of 150/100 mg was more efficacious in suppressing R155K in NS3 than a 100/100-mg dose. In patients who failed after receiving 12 or more weeks of treatment, RAVs were selected in all 3 targets, while most patients who relapsed after 8 weeks of treatment did so without any detectable RAVs. Results from this study guided the selection of the optimal treatment regimen, treatment duration, and paritaprevir dose for further development of the 3D regimen. (This study has been registered at ClinicalTrials.gov under registration number NCT01464827.).

In vitro and in vivo antiviral activity and resistance profile of ombitasvir, an inhibitor of hepatitis C virus NS5A.

Ombitasvir (ABT-267) is a hepatitis C virus (HCV) NS5A inhibitor with picomolar potency, pan-genotypic activity, and 50% effective concentrations (EC50s) of 0.82 to 19.3 pM against HCV genotypes 1 to 5 and 366 pM against genotype 6a. Ombitasvir retained these levels of potency against a panel of 69 genotype 1 to 6 chimeric replicons containing the NS5A gene derived from HCV-infected patients, despite the existence of natural sequence diversity within NS5A. In vitro resistance selection identified variants that conferred resistance to ombitasvir in the HCV NS5A gene at amino acid positions 28, 30, 31, 58, and 93 in genotypes 1 to 6. Ombitasvir was evaluated in vivo in a 3-day monotherapy study in 12 HCV genotype 1-infected patients at 5, 25, 50, or 200 mg dosed once daily. All patients in the study were HCV genotype 1a infected and were without preexisting resistant variants at baseline as determined by clonal sequencing. Decreases in HCV RNA up to 3.1 log10 IU/ml were observed. Resistance-associated variants at position 28, 30, or 93 in NS5A were detected in patient samples 48 hours after the first dose. Clonal sequencing analysis indicated that wild-type virus was largely suppressed by ombitasvir during 3-day monotherapy, and at doses higher than 5 mg, resistant variant M28V was also suppressed. Ombitasvir was well tolerated at all doses, and there were no serious or severe adverse events. These data support clinical development of ombitasvir in combination with inhibitors targeting HCV NS3/4A protease (ABT-450 with ritonavir) and HCV NS5B polymerase (ABT-333, dasabuvir) for the treatment of chronic HCV genotype 1 infection. (Study M12-116 is registered at ClinicalTrials.gov under registration no. NCT01181427.).

Posterior predictive Bayesian phylogenetic model selection.

We present two distinctly different posterior predictive approaches to Bayesian phylogenetic model selection and illustrate these methods using examples from green algal protein-coding cpDNA sequences and flowering plant rDNA sequences. The Gelfand-Ghosh (GG) approach allows dissection of an overall measure of model fit into components due to posterior predictive variance (GGp) and goodness-of-fit (GGg), which distinguishes this method from the posterior predictive P-value approach. The conditional predictive ordinate (CPO) method provides a site-specific measure of model fit useful for exploratory analyses and can be combined over sites yielding the log pseudomarginal likelihood (LPML) which is useful as an overall measure of model fit. CPO provides a useful cross-validation approach that is computationally efficient, requiring only a sample from the posterior distribution (no additional simulation is required). Both GG and CPO add new perspectives to Bayesian phylogenetic model selection based on the predictive abilities of models and complement the perspective provided by the marginal likelihood (including Bayes Factor comparisons) based solely on the fit of competing models to observed data.

Efficacy and safety of linaclotide in treating functional constipation in paediatric patients: a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial.

BACKGROUND: Linaclotide, a guanylate cyclase C agonist, has been approved in the USA for the treatment of chronic idiopathic constipation and irritable bowel syndrome with predominant constipation in adults. We aimed to assess the efficacy and safety of linaclotide in paediatric patients aged 6-17 years with functional constipation. METHODS: This randomised, double-blind, placebo-controlled, multicentre, phase 3 study was done at 64 clinic or hospital sites in seven countries (USA, Canada, Israel, Italy, the Netherlands, Ukraine, and Estonia). Patients aged 6-17 years who met modified Rome III criteria for functional constipation were randomly assigned (1:1), with a block size of four and stratified by age (6-11 years and 12-17 years), to receive either oral linaclotide 72 µg or placebo once daily for 12 weeks. Participants, investigators, and data assessors were masked to assignment. The primary efficacy endpoint was change from baseline (CFB) in the 12-week frequency rate of spontaneous bowel movements (SBMs; occurring in the absence of rescue medication on the calendar day of or before the bowel movement) per week and the secondary efficacy endpoint was CFB in stool consistency over the 12-week treatment period; efficacy and safety were analysed in all patients in the randomised population who received at least one dose of study intervention (modified intention-to-treat population and safety population, respectively). The study is registered with ClinicalTrials.gov, NCT04026113, and the functional constipation part of the study is complete. FINDINGS: Between Oct 1, 2019, and March 21, 2022, 330 patients were enrolled and randomly assigned to linaclotide (n=166) or placebo (n=164). Two patients in the linaclotide group did not receive any treatment; thus, efficacy and safety endpoints were assessed in 328 patients (164 patients in each group). 293 (89%) patients completed the 12-week treatment period (148 in the linaclotide group and 145 in the placebo group). 181 (55%) of 328 patients were female and 147 (45%) were male. At baseline, the mean frequency rate for SBMs was 1·28 SBMs per week (SD 0·87) for placebo and 1·16 SBMs per week (0·83) for linaclotide, increasing to 2·29 SBMs per week (1·99) for placebo and 3·41 SBMs per week (2·76) for linaclotide during intervention. Compared with placebo (least-squares mean [LSM] CFB 1·05 SBMs per week [SE 0·19]), patients treated with linaclotide showed significant improvement in SBM frequency (LSM CFB 2·22 SBMs per week [0·19]; LSM CFB difference 1·17 SBMs per week [95% CI 0·65-1·69]; p<0·0001). Linaclotide also significantly improved stool consistency over placebo (LSM CFB 1·11 [SE 0·08] vs 0·69 [0·08]; LSM CFB difference 0·42 [95% CI 0·21-0·64]; p=0·0001). The most reported treatment-emergent adverse event (TEAE) by patients treated with linaclotide was diarrhoea (seven [4%] of 164 vs three [2%] of 164 patients in the placebo group) and by patients treated with placebo was COVID-19 (five [3%] vs four [2%] in the linaclotide group). The most frequent treatment-related TEAE was diarrhoea (linaclotide: six [4%] patients; placebo: two [1%] patients). One serious adverse event of special interest (treatment-related severe diarrhoea resulting in dehydration and hospitalisation) occurred in a female patient aged 17 years in the linaclotide group; this case resolved without sequelae after administration of intravenous fluids. No deaths occurred during the study. INTERPRETATION: Linaclotide is an efficacious and well tolerated treatment for functional constipation in paediatric patients and has subsequently been approved by the US Food and Drug Administration for this indication. FUNDING: AbbVie and Ironwood Pharmaceuticals.

Improving marginal likelihood estimation for Bayesian phylogenetic model selection.

The marginal likelihood is commonly used for comparing different evolutionary models in Bayesian phylogenetics and is the central quantity used in computing Bayes Factors for comparing model fit. A popular method for estimating marginal likelihoods, the harmonic mean (HM) method, can be easily computed from the output of a Markov chain Monte Carlo analysis but often greatly overestimates the marginal likelihood. The thermodynamic integration (TI) method is much more accurate than the HM method but requires more computation. In this paper, we introduce a new method, steppingstone sampling (SS), which uses importance sampling to estimate each ratio in a series (the "stepping stones") bridging the posterior and prior distributions. We compare the performance of the SS approach to the TI and HM methods in simulation and using real data. We conclude that the greatly increased accuracy of the SS and TI methods argues for their use instead of the HM method, despite the extra computation needed.

Upadacitinib Treatment Improves Symptoms of Bowel Urgency and Abdominal Pain, and Correlates With Quality of Life Improvements in Patients With Moderate to Severe Ulcerative Colitis.

BACKGROUND AND AIMS: Bowel urgency and abdominal pain are impactful, yet under-appreciated ulcerative colitis symptoms and not commonly assessed in clinical trials. We evaluated how these symptoms may improve with upadacitinib treatment and correlate with clinical and health-related quality of life [HRQOL] outcomes in the phase 2b U-ACHIEVE study. METHODS: Patients aged 18-75 years, with moderately to severely active ulcerative colitis, were randomised to receive placebo or upadacitinib (7.5, 15, 30, or 45 mg once daily [QD]). Bowel urgency and abdominal pain were evaluated at baseline and Weeks 2, 4, 6, and 8. Week 8 correlations were evaluated between bowel urgency/abdominal pain with clinical [Mayo subscores and high-sensitivity C-reactive protein and faecal calprotectin measurements] and HRQOL outcomes [Inflammatory Bowel Disease Questionnaire and 36-Item Short Form Health Survey scores]. RESULTS: A greater proportion of patients [n = 250] reported no bowel urgency and less abdominal pain with upadacitinib treatment compared with placebo, with improvements observed as early as 2 weeks. At Week 8, patients receiving the 45-mg QD dose had the greatest improvements versus placebo, with 46% reporting no bowel urgency [vs 9%; p ≤ 0.001] and 38% reporting no abdominal pain [vs 13%; p = 0.015]. At Week 8, moderate correlations were found between bowel urgency or abdominal pain and most clinical and HRQOL outcomes. CONCLUSIONS: Induction treatment with upadacitinib demonstrated significant reductions in bowel urgency and abdominal pain compared with placebo. These symptoms also correlate to clinical and HRQOL outcomes, supporting their use to monitor disease severity and other treatment outcomes.

Hepatitis C virus genetic diversity by geographic region within genotype 1-6 subtypes among patients treated with glecaprevir and pibrentasvir.

Hepatitis C virus (HCV) is genetically diverse and includes 7 genotypes and 67 confirmed subtypes, and the global distribution of each HCV genotype (GT) varies by geographic region. In this report, we utilized a large dataset of NS3/4A and NS5A sequences isolated from 2348 HCV GT1-6-infected patients treated with the regimen containing glecaprevir/pibrentasvir (GLE/PIB) to assess genetic diversity within HCV subtypes by geographic region using phylogenetic analyses, and evaluated the prevalence of baseline amino acid polymorphisms in NS3 and NS5A by region/country and phylogenetic cluster. Among 2348 NS3/4A and NS5A sequences, phylogenetic analysis identified 6 genotypes and 44 subtypes, including 3 GT1, 8 GT2, 3 GT3, 13 GT4, 1 GT5, and 16 GT6 subtypes. Phylogenetic analysis of HCV subtype 1a confirmed the presence of two clades, which differed by geographic region distribution and NS3 Q80K prevalence. We detected phylogenetic clustering by country in HCV subtypes 1a, 1b, 2a, 2b, and 5a, suggesting that genetically distinct virus lineages are circulating in different countries. In addition, two clades were detected in HCV GT4a and GT6e, and NS5A amino acid polymorphisms were differentially distributed between the 2 clades in each subtype. The prevalence of NS3 and NS5A baseline polymorphisms varied substantially by genotype and subtype; therefore, we also determined the activity of GLE or PIB against replicons containing NS3/4A or NS5A from HCV GT1-6 clinical samples representing 6 genotypes and 21 subtypes overall. GLE and PIB retained activity against the majority of HCV replicons containing NS3/4A or NS5A from HCV GT1-6 clinical samples, with a median EC50 of 0.29 nM for GLE and 1.1 pM for PIB in a transient replicon assay. The data presented in this report expands the available data on HCV epidemiology, subtype diversity by geographic region, and NS3 and NS5A baseline polymorphism prevalence.

Efficacy and safety of glecaprevir/pibrentasvir in Japanese patients with chronic genotype 1 hepatitis C virus infection with and without cirrhosis.

BACKGROUND: The once-daily, all oral, RBV-free, pangenotypic direct-acting anti-viral regimen consisting of co-formulated NS3/4A protease inhibitor glecaprevir and NS5A inhibitor pibrentasvir (G/P), demonstrated high rates of sustained virologic response (SVR) in phase 2 and 3 studies outside Japan. METHODS: CERTAIN-1 is a phase 3, open-label, multicenter study assessing the safety and efficacy of G/P (300/120 mg) once daily in Japanese patients with chronic HCV GT1 infection. Patients without cirrhosis received 8 weeks of G/P or 12 weeks of ombitasvir/paritaprevir/ritonavir (OBV/PTV/r, 25/150/100 mg); patients with cirrhosis received G/P for 12 weeks. The primary efficacy endpoint was non-inferiority of G/P compared to OBV/PTV/r by assessing SVR at post-treatment week 12 (SVR12) among non-cirrhotic patients without the NS5A Y93H polymorphism. RESULTS: SVR12 was achieved by 128/129 (99.2%; one patient lost to follow-up) non-cirrhotic patients in the 8-week G/P Arm (including 23/23 patients with the NS5A Y93H polymorphism) and 52/52 (100%) patients in the 12-week OBV/PTV/r Arm. No patients from the G/P Arm prematurely discontinued the study drug or experienced a treatment-emergent serious adverse event (TESAE). Three patients from the OBV/PTV/r Arm experienced five TESAEs and one of these patients discontinued the study drug due to TESAEs. All 38 (100%) patients with compensated cirrhosis achieved SVR12; in this group, no TESAEs were reported and one patient discontinued treatment due to an AE. CONCLUSIONS: CERTAIN-1 study results demonstrate high efficacy and favorable tolerability of G/P in GT1-infected Japanese patients including those with the NS5A Y93H polymorphism, with no virologic failures observed.

Efficacy and safety of glecaprevir/pibrentasvir in HCV-infected Japanese patients with prior DAA experience, severe renal impairment, or genotype 3 infection.

BACKGROUND: Once-daily, orally administered, co-formulated glecaprevir (NS3/4A protease inhibitor) and pibrentasvir (NS5A inhibitor) (G/P) demonstrated pangenotypic activity and high sustained virologic response (SVR) rates in studies outside Japan. Here we report safety and efficacy in a subset of Japanese patients with chronic HCV infection who received G/P 300/120 mg in a phase 3, open-label, multicenter study (CERTAIN-1). METHODS: This analysis focuses on three difficult-to-treat subgroups: HCV GT1/2-infected patients who failed to achieve SVR after treatment with a direct acting antiviral (DAA)-containing regimen; GT1/2-infected patients with severe renal impairment (estimated glomerular filtration rate < 30 mL/min/1.73 m2); and GT3-infected patients. Patients in the renal impairment and GT3 cohorts were treatment-naive or interferon treatment-experienced. Noncirrhotic GT1/2-infected, DAA-naïve patients in the renal impairment cohort received G/P for 8 weeks; all other patients were treated for 12 weeks. Primary outcome was SVR (HCV RNA < 15 IU/mL) 12 weeks post-treatment (SVR12). RESULTS: The study enrolled 33 GT1/2-infected patients who failed previous DAA treatment (four with cirrhosis); 12 GT1/2-infected patients with severe renal impairment (two with cirrhosis); and 12 GT3-infected patients (two with cirrhosis). SVR12 was achieved by 31/33 (93.9%), 12/12 (100%), and 10/12 (83.3%) patients, respectively. One serious adverse event (fluid overload, not related to G/P) occurred in a patient on chronic intermittent hemodialysis. CONCLUSIONS: G/P achieved high SVR12 rates and was well tolerated in three difficult-to-treat patient subgroups with limited treatment options in Japan (DAA-experienced patients, patients with severe renal impairment, and GT3-infected patients). These results support the potential suitability of this regimen for these special populations in Japan.

Correction to: Efficacy and safety of glecaprevir/pibrentasvir in HCV-infected Japanese patients with prior DAA experience, severe renal impairment, or genotype 3 infection.

Unfortunately, in the original publication of this article, the copyright line was incorrectly published in PDF as "© The Author(s) 2017" instead of "©The Author(s) 2017 This article is an open access publication" and also the CC-BY description was not included. The description should be as follows.

Dose-ranging design and analysis methods to identify the minimum effective dose (MED).

In dose ranging clinical trials, it is critical to investigate the dose-response profile and to identify a minimum effective dose (MED) to guide the dose selection for phase 3 confirmatory trials. Traditional dose ranging trials focus on pairwise comparisons between placebo and each investigational dose, while in recent years MCP-Mod (Multiple Comparison Procedures & Modeling) arose and gained popularity in the design and analysis of dose ranging trials. Comprehensive comparison between MCP-Mod and other methods have been made on continuous variables assuming a normal distribution. In this article, we extend the comparison to binary/binomial response variables. Via simulation, the rate of correct and incorrect MED identification are compared for Dunnett's test, trend test and MCP-Mod for a variety of underlying dose response profiles including both monotone and non-monotone dose responses and are compared under a large number of trial design settings. The precision of MED estimation using MCP-Mod is also evaluated comparing the design options of more dose levels and smaller sample size per dose versus fewer dose levels and larger sample size per dose.