A Phase 2 interventional study of Ciraparantag and Placebo in Healthy, sponsored by Perosphere Pharmaceuticals Inc, a wholly owned subsidiary of AMAG Pharmaceuticals, Inc.. Completed at 1 site in United States. Open to participants aged 50 Years to 75 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-09-02.
Sponsored by Perosphere Pharmaceuticals Inc, a wholly owned subsidiary of AMAG Pharmaceuticals, Inc. (part of Azurity Pharmaceuticals) · Phase 2, Interventional, and Treatment
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This study is a randomized, single-blind, placebo-controlled study to assess the efficacy and safety of ciraparantag administered to healthy volunteers anticoagulated with rivaroxaban measuring clotting times using Whole Blood Clotting Time (WBCT).
This is a randomized, single-blind, placebo-controlled assessment of the efficacy and safety of ciraparantag administered to healthy volunteers measuring clotting times using WBCT as determined by the manual testing method. All subjects will undergo screening up to 36 days prior to enrollment.
All enrolled subjects are to receive a single dose of 20 mg rivaroxaban in the morning on Days 1-3. On Day 3 (3.75 hours post rivaroxaban), subjects who have a minimum increase in clotting time of 25% (as measured by WBCT) are randomized and will receive a single IV dose 4 hours after the rivaroxaban dose, followed by serial testing of manual WBCT.
Subjects are enrolled sequentially in up to 4 ciraparantag dose cohorts. There will be a safety review after completion of treatment in one cohort and prior to initiation of treatment in the subsequent cohort.
Perosphere Pharmaceuticals Inc, a wholly owned subsidiary of AMAG Pharmaceuticals, Inc. is the lead sponsor of 11 studies on the registry; none are open to participants now.
First submitted before Perosphere Pharmaceuticals Inc became part of Azurity Pharmaceuticals.
Counted across the registry records on this site, refreshed daily.
General Inclusion Criteria:
General Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ciraparantag (60 mg)
Drug: Ciraparantag · Drug: Rivaroxaban
ciraparantag (120 mg)
Drug: Ciraparantag · Drug: Rivaroxaban
ciraparantag (180 mg)
Drug: Ciraparantag · Drug: Rivaroxaban
ciraparantag (30 mg)
Drug: Ciraparantag · Drug: Rivaroxaban
placebo (saline for injection)
Drug: Placebo · Drug: Rivaroxaban
Ciraparantag (administered over 10 minutes)
Also known as: PER977, AMAG 977
Saline for injection
Also known as: PBO
Rivaroxaban 20 mg given once per day (QD) in the morning
Subjects Achieving Complete Reversal of Anticoagulation (WBCT is ≤ 110% of Baseline)
Complete reversal is achieved if WBCT (manual method) is ≤ 110% of baseline at any post-baseline time point up to and including 1 hour following ciraparantag/placebo administration)
Time frame: Within 1 Hour
Subjects Achieving Complete and Sustained Reversal of Anticoagulation (WBCT is ≤115%of Baseline)
Complete and sustained reversal of anticoagulation is achieved for a subject if WBCT (manual method) is ≤ 115% of baseline at all time points between 1 and 8 hours (inclusive) following ciraparantag/placebo administration.
Time frame: Between 1 and 8 Hours
One study site in the US enrolled subjects between May 2017 and November 2019
| Milestone | Placebo | Ciraparantag 30mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg |
|---|---|---|---|---|---|
| Started | 16 | 12 | 12 | 12 | 12 |
| Completed | 16 | 12 | 12 | 12 | 11 |
| Not completed | 0 | 0 | 0 | 0 | 1 |
| Withdrew: Adverse event | 0 | 0 | 0 | 0 | 1 |
Complete reversal is achieved if WBCT (manual method) is ≤ 110% of baseline at any post-baseline time point up to and including 1 hour following ciraparantag/placebo administration)
| Participants | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg |
|---|---|---|---|---|---|
| Subjects Achieving Complete Reversal of Anticoagulation (WBCT is ≤ 110% of Baseline) | 3 | 7 | 11 | 11 | 12 |
Complete and sustained reversal of anticoagulation is achieved for a subject if WBCT (manual method) is ≤ 115% of baseline at all time points between 1 and 8 hours (inclusive) following ciraparantag/placebo administration.
| Participants | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg |
|---|---|---|---|---|---|
| Subjects Achieving Complete and Sustained Reversal of Anticoagulation (WBCT is ≤115%of Baseline) | 3 | 8 | 11 | 11 | 12 |
Collected over All AEs occurring after the subject signed the informed consent through the last study visit 7 to 10 days following ciraparantag/PBO administration). SAEs occurring up to 30 calendar days post treatment were collected.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Placebo | 0/16 (0%) | 0/16 (0%) | 3/16 (18.8%) |
| Ciraparantag 30 mg | 0/12 (0%) | 0/12 (0%) | 0/12 (0%) |
| Ciraparantag 60 mg | 0/12 (0%) | 0/12 (0%) | 2/12 (16.7%) |
| Ciraparantag 120 mg | 0/12 (0%) | 0/12 (0%) | 8/12 (66.7%) |
| Ciraparantag 180 mg | 0/12 (0%) | 1/12 (8.3%) | 10/12 (83.3%) |
| Enrolled Not Randomized | 0/5 (0%) | 0/5 (0%) | 1/5 (20%) |
| Event | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Enrolled Not Randomized |
|---|---|---|---|---|---|---|
| Supraventricular TachycardiaCardiac disorders | — | — | — | — | 1/12 | — |
| Event | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Enrolled Not Randomized |
|---|---|---|---|---|---|---|
| Hot FlushVascular disorders | 0/16 | 0/12 | 0/12 | 4/12 | 5/12 | 0/5 |
| Electrocardiogram T wave inversionInvestigations | 0/16 | 0/12 | 0/12 | 0/12 | 0/12 | 1/5 |
| ParaesthesiaNervous system disorders | 0/16 | 0/12 | 0/12 | 1/12 | 2/12 | 0/5 |
| DizzinessNervous system disorders | 0/16 | 0/12 | 2/12 | 0/12 | 0/12 | 0/5 |
| Feeling coldGeneral disorders | 0/16 | 0/12 | 1/12 | 1/12 | 2/12 | 0/5 |
| Feeling hotGeneral disorders | 0/16 | 0/12 | 0/12 | 0/12 | 2/12 | 0/5 |
| FlushingVascular disorders | 0/16 | 0/12 | 0/12 | 1/12 | 1/12 | 0/5 |
| DysgeusiaNervous system disorders | 0/16 | 0/12 | 0/12 | 1/12 | 1/12 | 0/5 |
| HeadacheNervous system disorders | 1/16 | 0/12 | 0/12 | 1/12 | 1/12 | 0/5 |
| Chest discomfortGeneral disorders | 0/16 | 0/12 | 0/12 | 0/12 | 1/12 | 0/5 |
A total of 69 subjects were enrolled, and all of these subjects received at least 1 dose of rivaroxaban. Of these 69 subjects, 5 were not randomized, did not receive study drug (ciraparantag or placebo), and were discontinued from the study.
| Age, Continuous(years) | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Total |
|---|---|---|---|---|---|---|
| Mean | 54.3 ± 3.89 | 57.8 ± 5.67 | 56.1 ± 6.73 | 53.8 ± 3.10 | 55.9 ± 4.89 | 55.5 ± 5.00 |
| Sex: Female, Male(Participants) | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Total |
|---|---|---|---|---|---|---|
| Female | 2 | 2 | 2 | 0 | 3 | 9 |
| Male | 14 | 10 | 10 | 12 | 9 | 55 |
| Race/Ethnicity, Customized(Participants) | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Total |
|---|---|---|---|---|---|---|
| White | 8 | 6 | 6 | 7 | 5 | 32 |
| Black or African American | 8 | 6 | 6 | 5 | 5 | 30 |
| Asian | 0 | 0 | 0 | 0 | 2 | 2 |
| Region of Enrollment(Participants) | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Total |
|---|---|---|---|---|---|---|
| United States | 16 | 12 | 12 | 12 | 12 | 64 |
| Baseline Whole Blood Clotting Time (WBCT, manual method)(minutes) | Placebo | Ciraparantag 30 mg | Ciraparantag 60 mg | Ciraparantag 120 mg | Ciraparantag 180 mg | Total |
|---|---|---|---|---|---|---|
| Mean | 7.8 ± 0.36 | 8.1 ± 0.42 | 7.8 ± 0.25 | 7.8 ± 0.33 | 7.9 ± 0.36 | 7.9 ± .34 |
PDFs hosted by the registry, ClinicalTrials.gov.
Ran from May 2017 to primary completion in Nov 2019, 30 months.
Results were first posted in Sep 2025, 5 years 9 months after primary completion. A results delay was requested in Sep 2020.
How these figures are worked out, and which studies are left out of them.
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Studies of the drug tested here: PER977
Perosphere Pharmaceuticals Inc, a wholly owned subsidiary of AMAG Pharmaceuticals, Inc. →