Fetal and Neonatal Alloimmune ThrombocytopeniaPhase 2NCT06435845
Phase 2 Study on the Pharmacokinetics and Safety of RLYB212 in Pregnant Women at Higher Risk for HPA-1a Alloimmunization
A Phase 2 study testing Anti-(integrin beta-3) human monoclonal antibody in people with Fetal and Neonatal Alloimmune Thrombocytopenia, run by Rallybio at 3 sites in 3 countries.
Trial summary
The purpose of this Phase 2 study is to assess the pharmacokinetics (PK) and safety of RLYB212 in HPA-1b/b pregnant women at higher risk for HPA-1a alloimmunization and FNAIT. Read more about this study
- Who is it for?
- Ages 18 to 45 years, women only
- Conditions the study is for
- Fetal and Neonatal Alloimmune Thrombocytopenia
- What is being tested?
- Anti-(integrin beta-3) human monoclonal antibody
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 1 participants
- Where
- 3 sitesin 3 countries
- Study dates
- 21 Nov 2024to 1 Oct 2025
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 45 years
- Women only
- No healthy volunteers
- Adult
Who may be able to join
- Pregnant women who present at Gestational Week 6 or after and confirmed to be: HPA-1b/b (HPA-1a negative), HLA-DRB301:01 positive, Anti-HPA-1a alloantibody negative, Carrying an HPA-1a/b (HPA-1a positive) fetus
Who cannot join
- Prior history of HPA-1a related fetal and neonatal alloimmune thrombocytopenia
- Multiple pregnancy (more than 1 fetus)
- Prior history of platelet transfusion or other blood transfusions
- Known sensitivity and/or immediate hypersensitivity to any components of RLYB212 or its formulation
- Any co-morbid medical or obstetric condition(s), laboratory abnormality, concomitant treatment, or other reason that, in the investigator's opinion, could adversely affect the safety of the participant and/or fetus, impair the assessment of study results, or preclude compliance with the study
Trial locations and contacts
3 sites in 3 countries.
3 sites in 3 countries
Netherlands1 site
Leids Universitair Medisch Centrum
Leiden, South Holland, 2333
About this study
Official title: A Phase 2, Multicenter, Open-label Study to Evaluate the Pharmacokinetics and Safety of RLYB212 in Pregnant Women at Higher Risk for HPA-1a Alloimmunization
The purpose of this Phase 2 study is to assess the pharmacokinetics (PK) and safety of RLYB212 in HPA-1b/b pregnant women at higher risk for HPA-1a alloimmunization and FNAIT.
Read the detailed description
This study is a single-arm, open-label, multicenter study of RLYB212 in HPA-1b/b pregnant participants at higher risk for the occurrence of HPA-1a alloimmunization and FNAIT. A laboratory testing paradigm will be applied at screening to identify women at higher risk for HPA-1a alloimmunization. Study IPA2202 is comprised of three phases: a two-part screening phase, an antenatal treatment phase, and a postpartum follow-up phase. Study duration for each participant is anticipated to be ~44 weeks, inclusive of the screening visits through the Week 10 postpartum visit.
- Being tested
- Anti-(integrin beta-3) human monoclonal antibody
- Medical subject headings
- Thrombocytopenia, Neonatal Alloimmune
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Anti-(integrin beta-3) human monoclonal antibodyDrug
Also called RLYB212
human monoclonal anti-human platelet antigen (HPA)-1a immunoglobulin G antibody
| Study group | Role | What they receive |
|---|---|---|
| RLYB212 | Experimental | RLYB212 Subcutaneous injection Receives: Drug: Anti-(integrin beta-3) human monoclonal antibody |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants With Treatment Related Adverse Events as Defined by CTCAE 5.0
Adverse Events will be collected throughout the study from the time of screening part 2 and beyond until the end of study visit (10 weeks postpartum for the maternal participant and 4-6 weeks of age for the neonate/infant). MedDRA version 27.0 or above will be used to code the AEs. All maternal AEs will be graded according to the National Cancer Institute of Common Terminology Criteria for AEs (CTCAE version 5.0 or higher) and Maternal and Fetal Adverse Event Terminology (MFAET version 1.0 or higher).
Measured: Approx. Gestational Week (GW) <16, 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38; at birth (~40), Post Partum (PP) Week 4, 10 week
Maternal Exposure to RLYB212 as Measured in Serum
The PK profile of RLYB212 during pregnancy following repeat SC administration was evaluated. Results reported in concentration only.
Measured: Approx. GW 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38, at birth (~40), PP Week 4
Secondary outcomes (7)
Neonatal Exposure to RLYB212 as Measured in Cord Blood
The neonatal exposure to RLYB212 was to be measured by sampling and measuring the concentration of RLYB212 in a cord blood sample.
Measured: At birth (~GW 40)
Number of HPA-1a Positive Neonates With Treatment Related Adverse Events as Defined by CTCAE v5.0
The safety of RLYB212 in the HPA-1a positive neonate would be assessed by treatment related adverse events as defined by CTCAE v5.0
Measured: At birth (~GW 40), Approx. PP Week 4
Pregnancy Outcomes: Incidence of Live Births, Spontaneous Abortions, Elective Abortions, Still Births or Premature Births
The pregnancy and neonatal outcomes following antenatal RLYB212 administration was assessed by reporting incidence of live births, spontaneous abortions, elective abortions, still births or premature births.
Measured: At birth (~GW 40)
Frequency of Neonatal Thrombocytopenia as Measured by Platelet Count Within 72 Hours of Delivery
The occurrence of neonatal thrombocytopenia following antenatal RLYB212 administration was assessed.
Measured: At birth (~GW 40)
Frequency of HPA-1a Alloimmunization as Measured by Anti-HPA-1a Alloantibodies
The occurrence of HPA-1a alloimmunization was to be assessed by looking for anti-HPA-1a alloantibodies in the woman's blood.
Measured: Approx. PP Week 10
Neonatal Outcomes: General Health and Overall Status as Defined by Absolute Values and Percentiles
Neonate general health measured by Body Length (for age percentile) , Head Circumference (for age percentile), Weight for Height Percentile (for age percentile)
Measured: 4-6 weeks following delivery
Participants That Test Positive for Anti-RLYB212 Antibodies as Measured in Their Serum
Participants that test positive for Anti-RLYB212 antibodies as measured in their serum. The immunogenicity of RLYB212 was assessed by testing serum samples for absence or presence of ADAs. The detection and characterization of ADA against RLYB212 will be performed using a validated assay method by or under the supervision of the Sponsor. The titer of confirmed positive samples will be reported as well as the presence of neutralizing antibodies. Other analyses may be performed to verify the stability of antibodies to RLYB212, and/or further characterize the immunogenicity of RLYB212.
Measured: 16, 20, 24, 28, 32, 36, at birth (~40), PP Week 4
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 May 2024
- Study start21 Nov 2024
- Primary completion1 Oct 2025
- Study completion1 Oct 2025
Why it stopped: This study was terminated early by the sponsor due to insufficient drug exposure to achieve the intended therapeutic effect.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Fetal and Neonatal Alloimmune ThrombocytopeniaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Prevention
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 1 participants (actual)
Sponsor and investigators
- Lead sponsor
- Rallybio
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06435845
- Sponsor's protocol ID
- IPA2202
- Other IDs
- 2024-512651-20-00
- Status last verified
- Mar 2026
- First submitted
- 21 May 2024
- Last updated
- 6 Mar 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2, Multicenter, Open-label Study to Evaluate the Pharmacokinetics and Safety of RLYB212 in Pregnant Women at Higher Risk for HPA-1a Alloimmunization
- ClinicalTrials.gov ID
- NCT06435845
- Acronym / sponsor ID
- IPA2202
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: This study was terminated early by the sponsor due to insufficient drug exposure to achieve the intended therapeutic effect.
- Enrolment
- 1 participants (actual)
- Lead sponsor
- RallybioIndustry (pharma, biotech, devices)
- Study start
- 21 Nov 2024 (actual)
- Primary completion
- 1 Oct 2025 (actual)
- Study completion
- 1 Oct 2025 (actual)
- First posted
- 30 May 2024 (actual)
- Results
- Posted 6 Mar 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this Phase 2 study is to assess the pharmacokinetics (PK) and safety of RLYB212 in HPA-1b/b pregnant women at higher risk for HPA-1a alloimmunization and FNAIT.
Detailed description
This study is a single-arm, open-label, multicenter study of RLYB212 in HPA-1b/b pregnant participants at higher risk for the occurrence of HPA-1a alloimmunization and FNAIT. A laboratory testing paradigm will be applied at screening to identify women at higher risk for HPA-1a alloimmunization. Study IPA2202 is comprised of three phases: a two-part screening phase, an antenatal treatment phase, and a postpartum follow-up phase. Study duration for each participant is anticipated to be ~44 weeks, inclusive of the screening visits through the Week 10 postpartum visit.
Study design
- Primary purpose
- Prevention
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| RLYB212 | Experimental | Drug: Anti-(integrin beta-3) human monoclonal antibodyRLYB212 Subcutaneous injection |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- Pregnant women who present at Gestational Week 6 or after and confirmed to be: HPA-1b/b (HPA-1a negative), HLA-DRB301:01 positive, Anti-HPA-1a alloantibody negative, Carrying an HPA-1a/b (HPA-1a positive) fetus
Key exclusion criteria (5 listed)
- Prior history of HPA-1a related fetal and neonatal alloimmune thrombocytopenia
- Multiple pregnancy (more than 1 fetus)
- Prior history of platelet transfusion or other blood transfusions
- Known sensitivity and/or immediate hypersensitivity to any components of RLYB212 or its formulation
- Any co-morbid medical or obstetric condition(s), laboratory abnormality, concomitant treatment, or other reason that, in the investigator's opinion, could adversely affect the safety of the participant and/or fetus, impair the assessment of study results, or preclude compliance with the study
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Anti-(integrin beta-3) human monoclonal antibodyAlso: RLYB212human monoclonal anti-human platelet antigen (HPA)-1a immunoglobulin G antibody | Drug | RLYB212 |
Primary outcome
Number of Participants With Treatment Related Adverse Events as Defined by CTCAE 5.0
Time frame: Approx. Gestational Week (GW) <16, 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38; at birth (~40), Post Partum (PP) Week 4, 10 week
Adverse Events will be collected throughout the study from the time of screening part 2 and beyond until the end of study visit (10 weeks postpartum for the maternal participant and 4-6 weeks of age for the neonate/infant). MedDRA version 27.0 or above will be used to code the AEs. All maternal AEs will be graded according to the National Cancer Institute of Common Terminology Criteria for AEs (CTCAE version 5.0 or higher) and Maternal and Fetal Adverse Event Terminology (MFAET version 1.0 or higher).
Maternal Exposure to RLYB212 as Measured in Serum
Time frame: Approx. GW 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38, at birth (~40), PP Week 4
The PK profile of RLYB212 during pregnancy following repeat SC administration was evaluated. Results reported in concentration only.
7 secondary outcomes
Neonatal Exposure to RLYB212 as Measured in Cord Blood
Time frame: At birth (~GW 40)
Number of HPA-1a Positive Neonates With Treatment Related Adverse Events as Defined by CTCAE v5.0
Time frame: At birth (~GW 40), Approx. PP Week 4
Pregnancy Outcomes: Incidence of Live Births, Spontaneous Abortions, Elective Abortions, Still Births or Premature Births
Time frame: At birth (~GW 40)
Frequency of Neonatal Thrombocytopenia as Measured by Platelet Count Within 72 Hours of Delivery
Time frame: At birth (~GW 40)
Frequency of HPA-1a Alloimmunization as Measured by Anti-HPA-1a Alloantibodies
Time frame: Approx. PP Week 10
Neonatal Outcomes: General Health and Overall Status as Defined by Absolute Values and Percentiles
Time frame: 4-6 weeks following delivery
Participants That Test Positive for Anti-RLYB212 Antibodies as Measured in Their Serum
Time frame: 16, 20, 24, 28, 32, 36, at birth (~40), PP Week 4
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Mar 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
Related trials for Fetal and Neonatal Alloimmune Thrombocytopenia
RecruitingPhase 3
A Study of Nipocalimab or Intravenous Immunoglobulin (IVIG) in Pregnancies At Risk of Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT)
Thrombocytopenia, Neonatal Alloimmune
RecruitingPhase 3
A Study of Nipocalimab in Reducing the Risk of Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT)
Thrombocytopenia, Neonatal Alloimmune
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
3 sites in 3 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Anti-(integrin beta-3) human monoclonal antibody in people with Fetal and Neonatal Alloimmune Thrombocytopenia, run by Rallybio at 3 sites in 3 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 6 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Netherlands, Norway, Sweden. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 6 Mar 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of Participants With Treatment Related Adverse Events as Defined by CTCAE 5.0 (time frame: Approx. Gestational Week (GW) <16, 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38; at birth (~40), Post Partum (PP) Week 4, 10 week). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Mar 2026.