TerminatedPhase 2

Phase 2 Study on the Pharmacokinetics and Safety of RLYB212 in Pregnant Women at Higher Risk for HPA-1a Alloimmunization

Stopped: This study was terminated early by the sponsor due to insufficient drug exposure to achieve the intended therapeutic effect.

Netherlands, Norway, Sweden1 participantsStarted 2024-11-21

Plain-language 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.

Who can participate

Age range

18 Years – 45 Years

Sex

FEMALE

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: Pregnant women who present at Gestational Week 6 or after and confirmed to be: HPA-1b/b (HPA-1a negative), HLA-DRB3\*01:01 positive, Anti-HPA-1a alloantibody negative, Carrying an HPA-1a/b (HPA-1a positive) fetus Exclusion Criteria: * 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

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Since this trial has been terminated, can you tell me why it was stopped early, and what that means for the safety or effectiveness of RLYB212 as a potential treatment option for my situation?
2Because this was a Phase 2 study focused on pharmacokinetics and safety in pregnant women, what do we actually know so far about how RLYB212 behaves in the body during pregnancy, and is that data available anywhere?
3Given that this trial is no longer enrolling, are there any other active studies or alternative approaches being investigated for HPA-1a alloimmunization that might be worth considering for my pregnancy?
4Since fetal and neonatal alloimmune thrombocytopenia can be a serious condition, what are the current standard-of-care options available to me right now while research like this is still ongoing?
5If RLYB212 was being studied specifically in pregnant women at higher risk for HPA-1a alloimmunization, does my risk profile match that group, and how does that affect which monitoring or treatment path you'd recommend for me?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Number of Participants With Treatment Related Adverse Events as Defined by CTCAE 5.0

Timeframe: 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

Timeframe: Approx. GW 16, 18, 20, 24, 26, 28, 30, 32, 34, 36, 38, at birth (~40), PP Week 4

Trial details

NCT IDNCT06435845

SponsorRallybio

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2025-10-01

Results submitted2026-01-14

View on ClinicalTrials.gov More Fetal and Neonatal Alloimmune Thrombocytopenia trials