Medical Information Only. Always consult your healthcare provider before enrolling in any clinical trial.
NCT04732221 · ClinicalTrials.gov registry record · Phase 2
A Study of the Efficacy and Safety of Frespaciguat (MK-5475) in Participants With Pulmonary Arterial Hypertension (INSIGNIA-PAH: Phase 2/3 Study of an Inhaled sGC Stimulator in PAH) (MK-5475-007)
A Phase 2 study, sponsored by Merck Sharp & Dohme.
- Completed
- Registry status
- Phase 2
- Development phase
- 168
- Enrollment target
NCT04732221: Completed Phase 2 study, sponsored by Merck Sharp & Dohme.
NCT04732221 is a Phase 2 study that has completed, run by Merck Sharp & Dohme. The registered enrollment target is 168 participants, above the 133-participant average among 30,622 other Phase 2 trials with a reported enrollment target (26% higher). According to ClinicalTrials.gov, the official US trial registry.
The verdict
NCT04732221, a Phase 2 study, has completed, sponsored by Merck Sharp & Dohme.
- COMPLETED
- Registry status
- Phase 2
- Development phase
- 168 participants
- Enrollment target
Study Summary
This is a two-part (Phase 2/Phase 3) study of frespaciguat, an inhaled soluble guanylate cyclase stimulator, in participants with pulmonary arterial hypertension (PAH). The first part (Phase 2) will assess three different doses of frespaciguat compared to placebo in a base period of 12 weeks, followed by comparison of three different doses of frespaciguat during an optional 40 month extension period. The treatment dose with the best efficacy and safety profile in the phase 2 cohort base period will be selected for use in the second part (Phase 3) of the study. The primary hypothesis of Phase 2 is that at least one frespaciguat dose is superior to placebo in reducing pulmonary vascular resistance (PVR) from baseline at week 12. The purpose of the second part (Phase 3) of the study is to confirm the efficacy, safety, and tolerability of frespaciguat at the selected dose compared to placebo during a 12 week base period followed by an extension period of up to 5 years. The primary hypothesis of Phase 3 is that frespaciguat is superior to placebo in increasing 6-minute walk distance (6MWD) from baseline at week 12. Due to sponsor's decision this phase/part was not conducted.
Primary Outcome
PVR was calculated in participants after MK-5475 dosing at baseline and Week 12. PVR is assessed by right heart catheterization (RHC). Based on the variables obtained by right heart catheterization (RHC), the percentage change from baseline PVR was calculated. Per protocol, this outcome measure was assessed only for base period and was not assessed during extension period.
Interventions
- DRUG Frespaciguat
- DRUG Placebo to Frespaciguat
Trial Details
| Field | Value |
|---|---|
| Enrollment Target | 168 participants |
| Start Date | 2021-05-19 |
| Est. Completion | 2024-07-02 |
| Phase | Phase 2 |
What the finished NCT04732221 record still lists
NCT04732221 is an interventional study that assigns participants to a tested intervention. The registered 168 participants enrollment target is mid-sized for trials with a published cap, above the 133-participant average among 30,622 other Phase 2 trials with a reported enrollment target (26% higher).
The record links to 0 conditions, and to 2 interventions - of which Frespaciguat is the first listed.
NCT04732221 does not publish any study locations in the registry export this page uses.
Frequently Asked Questions
What is clinical trial NCT04732221 about?
NCT04732221 is a clinical study titled "A Study of the Efficacy and Safety of Frespaciguat (MK-5475) in Participants With Pulmonary Arterial Hypertension (INSIGNIA-PAH: Phase 2/3 Study of an Inhaled sGC Stimulator in PAH) (MK-5475-007)". This is a two-part (Phase 2/Phase 3) study of frespaciguat, an inhaled soluble guanylate cyclase stimulator, in participants with pulmonary arterial hypertension (PAH). The first part (Phase 2) will assess three different doses of frespaciguat compared to placebo in a base period of 12 weeks, follo...
What is the current status of trial NCT04732221?
This trial is currently completed. It is a Phase 2 study. The enrollment target is 168 participants. The study started on 2021-05-19. Estimated completion is 2024-07-02.
What interventions are being tested in trial NCT04732221?
The interventions under investigation include: Frespaciguat (DRUG), Placebo to Frespaciguat (DRUG).
Who is sponsoring clinical trial NCT04732221?
This trial is sponsored by Merck Sharp & Dohme, which has 558 total clinical trials registered on ClinicalTrials.gov.
Learn More About Clinical Trials
How this trial's enrollment target compares
Where NCT04732221's enrollment target sits among peer trials
168 403rd of 2000 higher than 1,595 of 2,000 other Phase 2 trials
participants (enrollment target), bucketed by value
Each bar is a band; taller bars hold more other Phase 2 trials. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source ClinicalTrials.gov registry export · 2026-08-08
Nationwide trials with similar profiles
Cross-condition peers matched on enrollment target and registry start date, not the same-condition list above.
Similar enrollment target
- NCT02118922 · 168 participants
A Study to Test the Diagnostic Potential of Brillouin Microscopy for Corneal Ectasia
- NCT03536897 · 168 participants
IORT Following Breast Conserving Surgery for Early Stage Breast Cancer Registry
- NCT04078230 · 168 participants · NA
Regional or Extend LymphAdenectomy During Resection of Intrahepatic Cholangiocarcinoma
- NCT04159168 · 168 participants · NA
Facial Affect Sensitivity Training for Young Children With Callous-unemotional Traits
Similar registry start date
- NCT05962346 · started 2026-12 · NA
Fetal Endoscopic Tracheal Occlusion for Congenital Diaphragmatic Hernia
- NCT07125183 · started 2026-12 · Phase 2
Study on Efficacy and Tolerability of Weekly Doxorubicin in Elderly Patients With Advanced or Metastatic Leiomyosarcoma
- NCT07292298 · started 2026-11 · Phase 2
Phase 2 Single-Arm Rectal Cancer Brachytherapy for Patients With Low-Lying Residual Adenocarcinoma After Total Neoadjuvant Therapy to Improve Organ Preservation Rates
- NCT04263285 · started 2026-10 · NA
Treatment of Depression Post-SCI