# Oral deucrictibant for prophylaxis of hereditary angioedema attacks (CHAPTER-1): primary analysis of a randomised, double-blind, placebo-controlled, phase 2 trial

- **DOI:** [10.1016/s2352-3026(26)00004-9](https://doi.org/10.1016/s2352-3026(26)00004-9)
- **Rating:** Strong (4.0 out of 5)
- **Verdict:** CHAPTER-1 establishes credible prophylactic efficacy for oral deucrictibant, but its 34-participant phase 2 sample limits precision and generalisability.
- **Framework version:** v5.9
- **Pipeline version:** v0.4
- **Evaluation date:** 2026-09-18
- **Evaluation page:** https://www.nabu.science/paper/10.1016%2Fs2352-3026(26)00004-9

## Key claims

1. Percent reduction in attack rate compared with placebo was 79.2% for deucrictibant 20 mg and 84.5% for deucrictibant 40 mg
   - Support: Supported
   - Type: Primary finding
   - Basis: prespecified blinded primary analysis shows consistent large reductions, with wide intervals and no multiplicity correction across doses
   - Location: Abstract; Results p e220; Table 2
2. The safety profile of deucrictibant was similar to that of placebo
   - Support: Supported
   - Type: Secondary
   - Basis: systematic adverse-event collection found similar short-term rates, but 34 participants cannot establish broader safety
   - Location: Research in context, Added value; Discussion p e224; Table 3
3. Improvements in patient-reported health-related quality of life and disease control and higher levels of satisfaction were consistent with clinical findings
   - Support: Tentative
   - Type: Secondary
   - Basis: patient-reported outcomes were descriptive and unadjusted for baseline differences or missing values
   - Location: Research in context, Added value; Results pp e221–e222
4. Consistent attack rate reductions in the deucrictibant groups compared with placebo were observed independent from baseline attack rates
   - Support: Tentative
   - Type: Secondary
   - Basis: post-hoc subgroup analysis was not powered to establish independence across baseline-rate strata
   - Location: Results, p e221; appendix p 20

## Strengths

- **First prophylactic test of the mechanism** The Research in context panel identifies no prior prophylaxis trial of bradykinin B2 receptor antagonism and distinguishes this mechanism from available kallikrein, C1-inhibitor, and factor XIIa approaches.
  - Dimension: contribution
  - Location: Research in context, pp e216–e217
- **Robust blinded primary trial architecture** Allocation used an interactive response system with baseline-rate stratification, matching capsules, and masking of patients, investigators, site personnel, and the sponsor. The primary endpoint was investigator-confirmed and analysed in the intention-to-treat set.
  - Dimension: methodological rigour
  - Location: Methods, Randomisation and masking and Statistical analysis, pp e217–e219
- **Clear development pathway toward phase three** The paper links this proof-of-concept study to a named larger and longer phase 3 trial using an extended-release, once-daily formulation and to a parallel on-demand development programme.
  - Dimension: application pathway
  - Location: Research in context, p e216; Discussion, pp e224–e225

## Limitations

- **Small homogeneous short-duration clinical sample** Only 34 adults were randomised, all were White, and treatment lasted 12 weeks. These features widen uncertainty and limit conclusions about broader populations and durable safety.
  - Dimension: methodological rigour
  - Location: Abstract Findings, p e215; Table 1; Limitations, p e224
- **Exploratory outcomes receive confident emphasis** Patient-reported outcomes were analysed descriptively without adjustment for baseline differences or missing values, yet they are narrated as corroborating and sustained findings in the Discussion.
  - Dimension: reporting
  - Location: Statistical analysis, p e219; Discussion, pp e223–e224
- **Sponsor control and sharing ambiguity** The sponsor participated throughout design, conduct, analysis, interpretation, and drafting. The Data sharing statement also calls the study ongoing despite the Summary and Methods describing it as complete.
  - Dimension: methodological rigour
  - Location: Role of the funding source, p e219; Data sharing, pp e225–e226

## Reliability checks

Caveats (4 of 4 checks).

- **Internal coherence:** Clean. Participant counts, efficacy estimates, confidence intervals, adverse-event totals, and stated analyses are mutually consistent. The absence of multiplicity adjustment and the descriptive status of secondary outcomes are disclosed methodological limitations rather than internal contradictions.
- **Research conduct:** Noted. Ethics approval, consent, registration, funding, and competing interests are declared, but sponsor involvement spans the full research and reporting process. The data-sharing statement also uses completion language that is inconsistent with the Summary and Methods.
- **Reference integrity:** Clean. 29 of 29 checkable references verified
  - 30 references in manuscript
  - 1 have no canonical index record — counted, but not index-checkable
  - 1 reference confirmed by manual review
  - References not verified automatically are resolved manually within 24 hours.

## Post-publication record

- **Status:** Clean
- **Summary:** No retraction or expression of concern found in Crossref (includes Retraction Watch).
- **Last checked:** 2026-10-17