Deucrictibant XR's 83% Attack Reduction Is Compelling, But Oral Efficacy Alone Won't Win HTA Without Quality-of-Life Proof

Pharvaris' Deucrictibant XR Achieves 83% HAE Attack Reduction in CHAPTER-3

Pharvaris reported statistically significant and clinically meaningful topline results from its CHAPTER-3 pivotal Phase 3 study of deucrictibant extended-release (XR) tablet for the prevention of hereditary angioedema (HAE) attacks. The study met its primary endpoint, demonstrating an 83% reduction in mean monthly attack rate versus placebo (p<0.0001) across all HAE types. All secondary efficacy endpoints were also met with statistical significance. Deucrictibant XR, administered once daily at 40 mg, was well-tolerated, with most adverse events being mild or moderate. These positive results will support marketing authorization applications planned for submission starting in the first half of 2027.

• The CHAPTER-3 study, a global Phase 3, double-blind, placebo-controlled trial, evaluated deucrictibant XR (40 mg, once daily) in 85 adolescents and adults with all three types of HAE. It achieved an 83% reduction in mean monthly attack rate compared to placebo (p<0.0001), with an 87% reduction observed specifically in participants with HAE Type 1 or Type 2. Protection was early-onset within the first week and sustained throughout the 24-week treatment period.
• Deucrictibant XR demonstrated a favorable safety profile, being well-tolerated by participants. Most treatment-emergent adverse events were mild or moderate, and no treatment-related serious adverse events were reported. Only one participant in each group discontinued treatment due to an adverse event, indicating good tolerability for long-term prophylactic use.
• These positive topline data from CHAPTER-3 will form the basis for planned marketing authorization applications, with submissions anticipated to begin in the first half of 2027. The company aims to establish deucrictibant XR as a potential new standard of care, offering injectable-like efficacy with the convenience of oral administration for HAE prophylaxis, complementing its immediate-release formulation for on-demand treatment.

Deucrictibant XR's Pivotal CHAPTER-3 Results: A New Era for HAE Prophylaxis

Recent clinical trials across HAE have evaluated a range of interventions — from oral small molecules to subcutaneous biologics — generating a growing body of efficacy and safety data. The studies below represent a cross-section of this evidence, spanning on-demand and prophylactic treatment modalities.

• KONFIDENT (sebetralstat): This phase 3, randomized, placebo-controlled, three-way crossover trial evaluated sebetralstat, an oral plasma kallikrein inhibitor, in patients aged ≥12 years with HAE with C1-inhibitor deficiency. The primary endpoint was time to beginning of symptom relief, defined as a Patient Global Impression of Change rating of at least "A Little Better" for two consecutive time points. In a pooled analysis of phase 2 and 3 data (377 attacks treated), median time to beginning of symptom relief was 1.6 h (IQR 0.8–7.0) with sebetralstat 300 mg and 1.8 h (IQR 1.0–4.3) with sebetralstat 600 mg, versus 8.3 h (IQR 1.5 to >12) with placebo (P = 0.0001 and P < 0.0001, respectively). Time to reduction in severity and complete attack resolution within 24 h were also significantly faster with both doses versus placebo. Sebetralstat had a safety profile comparable to placebo.

• OASIS-HAE (donidalorsen): This phase 3, randomized, placebo-controlled study evaluated donidalorsen, a triantennary N-acetyl galactosamine-conjugated antisense oligonucleotide targeting plasma prekallikrein mRNA, administered subcutaneously at 80 mg once every 4 weeks (Q4W) or once every 8 weeks (Q8W). Over Weeks 0 to 24, patients receiving donidalorsen experienced significant mean reductions in HAE attack rates versus placebo (Q4W: 81%; Q8W: 55%). Over Weeks 4 to 24, mean attack rates were reduced by 87% (Q4W) and 60% (Q8W) versus placebo. Reductions were sustained for up to 1 year in the OASISplus open-label extension (Q4W: 94%; Q8W: 95%). Across studies, donidalorsen had an acceptable safety and tolerability profile, with mostly mild to moderate adverse events reported.

• HELP trial (lanadelumab): This phase 3, randomized, double-blind, parallel-group, placebo-controlled trial evaluated lanadelumab, a fully human monoclonal antibody that selectively inhibits active plasma kallikrein, administered subcutaneously at 150 mg every 4 weeks, 300 mg every 4 weeks, or 300 mg every 2 weeks in patients aged ≥12 years with HAE type I or II. During the 26-week treatment period, mean attacks per month were 0.48, 0.53, and 0.26 for the three lanadelumab regimens, respectively, versus 1.97 for placebo. Mean differences in attack rate per month versus placebo were -1.49 (95% CI, -1.90 to -1.08; P < .001), -1.44 (95% CI, -1.84 to -1.04; P < .001), and -1.71 (95% CI, -2.09 to -1.33; P < .001). The most commonly occurring adverse events with greater frequency in the lanadelumab groups were injection site reactions (52.4% lanadelumab vs. 34.1% placebo) and dizziness (6.0% lanadelumab vs. 0% placebo).

• COMPACT trial (subcutaneous C1-esterase inhibitor [C1-INH SC]): This phase 3 trial evaluated C1-INH SC at doses of 40 IU/kg and 60 IU/kg twice weekly as routine prophylaxis in adolescents and adults. Safety analysis showed no dose-dependent relationship between C1-INH SC dose and the incidence of injection-site reactions or unsolicited adverse events. The proportion of injections followed by at least one injection-site reaction was 12% with 40 IU/kg, 5% with 60 IU/kg, and 6% with placebo. No anaphylaxis, thromboembolic, sepsis, or bacteremia events were reported during treatment. No inhibitory antibodies to C1-INH were observed, and all injection-site reactions resolved without leading to treatment discontinuation.

CHAPTER-3: Unpacking the Design and Safety Profile of Deucrictibant XR

Several pivotal trials have evaluated prophylactic and acute treatment strategies for hereditary angioedema (HAE), spanning subcutaneous C1 inhibitor preparations, plasma kallikrein inhibitors, and oral agents. The studies below represent a cross-section of phase 1b/2 through phase 4 designs, each with distinct patient populations, dosing regimens, and primary endpoints.

Deucrictibant XR's Potential to Redefine HAE Prophylaxis

The HAE treatment landscape has undergone substantial diversification over the past several years, with multiple mechanistic classes advancing through late-stage clinical development alongside established prophylactic agents. Lanadelumab, a subcutaneous plasma kallikrein inhibitor, has accumulated robust longitudinal evidence: a U.S.-based retrospective analysis of 141 patients maintained on lanadelumab for a mean of over 3.5 years (1,305 days ± 567) demonstrated that mean monthly attack rates ranged from 0.21 ± 0.43 during interval 1 to 0.16 ± 0.38 during interval 4 (P = .399 vs interval 1), with the proportion of attack-free patients increasing from 40% to 53% across follow-up intervals. Phase 3 data from Chinese and Japanese patient populations further confirmed this profile: in the Chinese study, the mean monthly attack rate decreased by 99.1% during days 0–182 versus run-in, with 90% of patients attack-free; in the Japanese study, the attack rate per month decreased by 74.0% over 52 weeks. Berotralstat, an oral plasma kallikrein inhibitor approved by the FDA in 2020, demonstrated a 67% reduction in HAE attacks at the standard 150-mg dose in the phase 3 APeX-2 trial, offering a once-daily oral alternative to injection-based regimens.

Beyond established agents, several investigational therapies have generated compelling phase 2 and phase 3 data. Donidalorsen, a subcutaneous antisense oligonucleotide targeting prekallikrein expression, demonstrated in a phase 3 double-blind randomized trial that dosing every 4 weeks reduced the least-squares mean time-normalized attack rate by 81% (95% CI, 65 to 89; P<0.001) versus placebo, with a median reduction from baseline of 90% in the 4-week group; 98% of adverse events were mild or moderate in severity. NTLA-2002, an in vivo CRISPR-Cas9 gene-editing therapy targeting the KLKB1 gene, produced dose-dependent reductions in total plasma kallikrein protein of -67%, -84%, and -95% at the 25-mg, 50-mg, and 75-mg dose levels, respectively, with a mean percentage change in angioedema attacks per month from baseline through the latest assessment of -95% across all patients; no severe adverse events were observed in this phase 1 dose-escalation study. Sebetralstat, an oral plasma kallikrein inhibitor, has completed a phase 3 trial as the first investigational oral on-demand treatment, and deucrictibant, an oral bradykinin B2 receptor antagonist, has completed phase 2 trials for both on-demand therapy and long-term prophylaxis.

Despite these therapeutic advances, real-world survey data from 13 countries highlight a persistent gap between available options and their uptake: of 260 adult participants, only 56 of 153 (36.6%) currently using any long-term prophylaxis reported using a first-line option per international guidelines. Participants reported a mean of 11.5 ± 14.2 HAE attacks in the 6 months before the survey, with moderate-to-large health-related quality of life impairment (AE-QoL total score 42.9 ± 23.2) and a mean overall work productivity loss of 26.9% ± 32.2. These findings underscore that the clinical burden of HAE remains substantial in populations not optimally managed, even as the pipeline continues to expand toward more durable, less burdensome modalities — including single-dose gene-editing approaches that aim for lifelong disease control.

Oral Deucrictibant: A New Era for HAE Prevention

The recent announcement of positive topline Phase 3 results for deucrictibant extended-release (XR) in hereditary angioedema (HAE) prophylaxis marks a significant milestone for patients and the pharmaceutical industry. With an impressive 83% reduction in mean monthly attack rate across all HAE types, this once-daily oral therapy demonstrates robust efficacy, building upon earlier Phase 2 data that first established bradykinin B2 receptor antagonism as a viable prophylactic strategy. This mechanism was previously proven for on-demand treatment, but its successful application in prevention represents a novel therapeutic approach.

For patients, an oral, once-daily option could dramatically improve adherence and quality of life, moving away from the burden of frequent parenteral injections. Strategically, this positions deucrictibant XR to be a significant market disruptor, offering a compelling convenience advantage in the HAE prophylaxis landscape. The strong data package, meeting all primary and secondary endpoints with statistical significance and showing a favorable safety profile, should facilitate a streamlined regulatory review process, with marketing authorization applications anticipated in early 2027.

However, several considerations remain as the drug moves towards commercialization. While short-term studies have shown deucrictibant XR to be well-tolerated with mild-to-moderate adverse events, the full long-term safety and tolerability profile with chronic daily administration will be crucial for sustained patient and prescriber confidence. Furthermore, the HAE treatment landscape is dynamic, with other oral and subcutaneous prophylactic therapies in development. Future market entries could intensify competition, requiring careful strategic positioning. Finally, while the Phase 3 results are reported across 'all HAE types,' detailed efficacy and safety data across the full spectrum of HAE types and diverse patient demographics from the larger trial will be important to fully understand its real-world applicability and potential nuances in response. This comprehensive understanding will be key to maximizing its impact in a competitive and evolving therapeutic area.