Carper, Benjamin

Importance Stool metabolites influencing gut motility and sensation may contribute to fecal incontinence (FI). Objective The objective of this study was to test whether FI is associated with higher levels of butyrate and Clostridiales taxa in stool. Study Design Stool metabolites and microbiota were compared between 96 women with FI and 42 controls. FI frequency and subtype (urgency vs insensible) were measured using a 14-day bowel diary, St. Mark’s score, and the Accidental Bowel Leakage questionnaire. Metabolite analysis included targeted analysis (8 short-chain fatty acids including butyrate, 17 bile acids, and 8 tryptophan derivatives) and untargeted analysis. Stool microbiota were characterized using 16S rRNA gene sequencing. Multivariable and exploratory multiomics factor analysis were performed with statistical significance defined as false discovery rate (FDR) ≤0.10. Results The FI group had a higher proportion of Bristol stool types 2 and 6 than controls ( P = 0.005). The mean number of leaks for the FI group was 1.7 ± 1.7 per day, 38% had urgency FI, and 39% had insensible FI. There was no significant difference between groups in butyrate levels and Clostridiales taxa. Multiomics analysis identified glycerolipids (monoacylglycerols and diacylglycerols) associated with FI (FDR = 0.08). In addition, insensible FI was associated with glycerolipids, long-chain saturated and monounsaturated fatty acids, phospholipids, and dipeptides (FDR = 0.08–0.09). The top weighted microbiota associated with these metabolites were Lachnospiraceae and Ruminococcaceae; however, these taxa were not directly associated with FI. Conclusion Butyrate and Clostridiales were not associated with FI. Novel stool metabolite signatures were identified, suggesting new biological pathways and potential therapeutic targets for FI.

Abstract Hereditary hemorrhagic telangiectasia (HHT) results in recurrent severe epistaxis, chronic gastrointestinal bleeding, and other morbid manifestations. Pomalidomide was recently demonstrated to be efficacious for bleeding in HHT in the landmark PATH-HHT trial. Given that the vascular remodeling that results in bleeding improvement may require several months, characteristics associated with treatment response would be invaluable to plan treatment. Using data from PATH-HHT (NCT03910244), we identified characteristics associated with change from baseline in Epistaxis Severity Score (ESS; a well-validated 10-point HHT bleeding scale and the trial’s primary end point) using multivariable-adjusted repeated-measures models. Characteristics associated with a better response to pomalidomide at weeks 16 to 24 of the trial included a higher (more severe) baseline ESS (change from baseline, −0.76 [95% confidence interval (CI), −0.99 to −0.54] points per 1-point higher baseline score, P< .001) and concomitant antifibrinolytic therapy (−0.73 [95% CI, −1.48 to 0.01] vs no therapy, P = .05). Characteristics associated with a less robust response were older age (0.29 [95% CI, 0.05-0.53] per 10 years older, P = .02) and underlying ACVRL1 germ line mutation (0.62 [95% CI, −0.04 to 1.27] vs ENG, SMAD4, or mutation not known, P = .06]. Characteristics notably associated with placebo response (placebo effect) were patient-reported outcome measures, such that those experiencing more severe disease at baseline had less placebo effect. In conclusion, several baseline patient and disease characteristics were associated with pomalidomide response, findings that may help guide patient selection for the use of pomalidomide in HHT. This trial was registered at www.Clinicaltrials.gov as NCT03910244.

Introduction Hereditary hemorrhagic telangiectasia (HHT), the second most common bleeding disorder worldwide, affects 1 in 5000 people and is characterized by extensive formation of telangiectasia and arteriovenous malformations (AVM) in mucosa, lung, brain, and liver. The primary clinical manifestation is recurrent, often severe epistaxis which commonly results in iron deficiency anemia, emergency room visits, hospitalizations, and reduced quality of life (QOL). Though non-randomized and/or underpowered studies have suggested that systemic bevacizumab or thalidomide may be effective in treating HHT, there have been no pivotal studies and therefore no FDA or EMA approved therapies. Methods PATH-HHT was an NHLBI-funded, randomized, placebo-controlled clinical trial conducted at 13 centers in the US to determine the safety and efficacy of pomalidomide for bleeding in HHT. Pomalidomide was supplied by Celgene and Bristol Myers Squibb. Patients were randomized in a 2:1 ratio to receive pomalidomide 4 mg daily or matching placebo for 6 months. Dose reductions were allowed for toxicity. The primary endpoint was the change in the Epistaxis Severity Score (ESS), a well-validated bleeding score in HHT, from baseline (randomization) to the end of the six-month treatment period, analyzed using a mixed model for repeated measures with adjustment for baseline value, center, treatment, visit, and treatment by visit interaction. Key secondary endpoints included 1) change in the average daily self-reported epistaxis duration from the four weeks preceding the baseline visit to weeks 20-24 of treatment, 2) amount of parenteral iron infused or blood transfused, and 3) change in QOL measurements, including an HHT-specific QOL score. Results PATH-HHT opened in November 2019 and was closed to enrollment by the NHLBI in June 2023 after a planned 75% interim analysis met a prespecified threshold for efficacy. A total of 144 patients were randomized and treated (95 pomalidomide, 49 placebo). Early study discontinuation was 25% in pomalidomide: 14% AE, 11% withdrawn, 1 unrelated death, compared with placebo (4% withdrawn). Across groups, 8% were terminated after 12 weeks for early study closure. Participants included 48% females, 11% non-white race; mean (± SD) age was 58.8±12.2 years. The mean ESS at baseline was 5.0±1.5 (4.9 pomalidomide, 5.2 placebo), consistent with moderate to severe epistaxis. At 24 weeks, the ESS in patients treated with pomalidomide decreased by a mean [95% CI] of -1.84 [-2.24, -1.44] and in the placebo group decreased by -0.89 [-1.39, -0.39] (mean difference -0.95 [-1.58, -0.32], p = 0.003) (Figure, Panel A). Difference between groups was apparent by 12 weeks (mean difference -0.52, 95% CI [-1.04, -0.01], p = 0.045). The HHT-specific QOL score, which ranges from 0 to 16 with higher scores indicating more limitations, also decreased more in the pomalidomide (mean -2.6, 95% CI [-3.3, -1.9]) vs the placebo group at 24 weeks (mean -1.2, 95% CI [-2.1, -0.3], p = 0.015) (Figure, Panel B). Adverse events that occurred more in the pomalidomide group included mild to moderate neutropenia (45% vs. 10%), constipation/diarrhea (60% vs. 37%), and rash (36% vs. 10%). Venous thrombosis occurred in 2% of patients in each group. Conclusion PATH-HHT is the largest and the first adequately powered, randomized trial of systemic therapy in HHT. The study demonstrated a significant and highly clinically relevant reduction in epistaxis in pomalidomide-treated patients as well as an improvement in the HHT-specific QOL score. Pomalidomide may offer a novel approach to management of HHT. Since plasma was collected from patients in this study before and at the end of treatment, additional studies may identify biomarkers predicting pomalidomide responses.