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Phase 2 Study of AGA2115 in Adults with Osteogenesis Imperfecta (COL1A1/COL1A2 Variants) Evaluating Bone Density

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What is this trial about?

A plain-language summary of the goals, design and what participants do

Osteogenesis Imperfecta is a rare genetic condition that makes bones break easily because of abnormal collagen, a protein that gives bone strength. Most adults with this condition have changes in the genes COL1A1 or COL1A2. The study investigates a new medicine called AGA2115, which is a human‑engineered antibody designed to bind to two proteins, sclerostin and dickkopf‑related protein 1, that normally limit bone growth. By blocking these proteins, the drug aims to help the body build stronger bone. Participants will receive the medicine as a subcutaneous injection (a shot under the skin) or a matching placebo that looks the same but does not contain the active drug.

The main goal of the trial is to see whether AGA2115 can increase bone mineral density (BMD) in the lumbar spine after one year of treatment. Adults with the condition will be randomly assigned to either the active drug or the placebo group and will be followed for about 12 months, with regular visits to check safety and measure bone density. The study will collect information on any side effects and overall health while participants continue their usual care.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessments

    baseline assessments are performed shortly after joining the trial. these include measurements of bone density at the lumbar spine, collection of medical history, and laboratory tests to establish starting values.

  2. Step 2

    First medication administration

    The first dose of the study medication is given after baseline assessments are completed.

    If assigned to the active group, the participant receives AGA2115 as a subcutaneous injection (injection under the skin) of 2000 mg. the injection is delivered in a solution for injection.

    If assigned to the control group, a matching placebo injection is given in the same manner.

  3. Step 3

    Regular follow‑up visits

    The participant returns to the study site for scheduled visits. during each visit, safety checks, blood tests, and assessments of bone health are performed.

    The study medication or placebo is administered at each visit according to the schedule defined by the trial protocol.

    The visits continue for the duration of the trial, which includes a total period of 12 months of treatment.

  4. Step 4

    Month 12 evaluation

    At month 12, a detailed measurement of lumbar spine bone mineral density (lumbar spine BMD) is performed.

    The primary outcome is the percent change from the baseline value measured at the start of the trial.

  5. Step 5

    Study completion

    After the month 12 evaluation, the participant completes the trial.

    Final safety assessments and study documentation are completed before the study ends.

Who can join the trial?

3 criteria

  • Be a man or a woman between 18 and 75 years old who has been diagnosed with osteogenesis imperfecta type I, III, or IV, and who has had genetic testing that shows changes in the COL1A1 or COL1A2 genes (these are the genes that help make strong bone protein).
  • Be able to sign an informed consent form, meaning you understand the study and agree to follow the rules and requirements written in the consent document and study plan.
  • Have a bone density measurement called a BMD (bone mineral density) with a T-score of –1.0 or lower at one of the following places: the lower back (lumbar spine), the upper part of the thigh bone (total hip), or the upper part of the thigh bone near the hip (femoral neck). A lower T-score means weaker bones.

Who cannot join the trial?

12 criteria

  • Having a low level of Vitamin D, which means the body does not have enough of this vitamin for healthy bones.
  • Having had cancer (also called malignancy) diagnosed or treated within the last 5 years.
  • Being pregnant, breastfeeding, or planning to become pregnant at any time during the study.
  • Having taken part in another clinical trial that gave a study drug within the past 12 months, or being enrolled in another trial at the same time.
  • Having uncontrolled diseases that affect bone health, such as abnormal parathyroid or thyroid function, or other hormone disorders.
  • Having a high or low level of blood calcium (hypercalcemia or hypocalcemia).
  • Having a history of rickets, osteomalacia, or any bone condition other than osteogenesis imperfecta that causes long‑bone deformities or a higher risk of fractures.
  • Having taken bisphosphonate medicines (drugs used to treat bone loss) within the past 6 months.
  • Having taken teriparatide, abaloparatide, strontium ranelate, or hormone replacement therapy within the past 12 months.
  • Having taken denosumab (or similar drugs) within the past 2 years.
  • Having ever taken anti‑sclerostin antibody medicines such as romosozumab, setrusumab, or blosozumab.
  • Having had a heart attack, stroke, or other major cardiovascular event within the past 12 months.
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Investigated drugs

AGA2115 is an experimental medicine that uses a specially designed antibody to block two proteins, sclerostin and dickkopf‑related protein 1, which normally stop bone from forming. By inhibiting these proteins, the drug aims to help the body build stronger bone. It is given as a liquid that is injected under the skin. In this study, the medicine is being tested to see if it can increase bone density in adults with osteogenesis imperfecta, a condition that makes bones fragile.

What is already known about the treatment

  • Placebo to match AGA2115

    The placebo is a sterile solution for injection that is given by subcutaneous injection in the same volume as the active drug. It contains no active ingredients and is used only as a control in the clinical trial. It is not an approved medication and has no therapeutic purpose, serving solely to allow comparison with the test product.

  • AGA2115

    AGA2115 is a solution for injection given by subcutaneous injection at a dose of 2000 mg, and it is a humanised IgG4 bispecific monoclonal antibody that targets sclerostin and dickkopf‑related protein 1. The drug is still investigational, currently in Phase 2 trials for adults with type I, III, or IV osteogenesis imperfecta, and is not yet approved for any indication. It is intended to treat osteogenesis imperfecta by blocking two proteins that normally slow bone growth, thereby helping the body build stronger bone. Its pharmacological class is a bispecific monoclonal antibody used as a bone‑building (anabolic) agent.

Investigated diseases

Osteogenesis Imperfecta - Osteogenesis Imperfecta is a genetic disorder that makes bones unusually weak and prone to breaking. People with the condition often experience fractures with little or no injury, especially during childhood. As they grow, the bones may become curved or misshapen, leading to a shorter stature. The disorder can also cause teeth that break easily and a tendency to develop joint stiffness. Over time, repeated fractures and bone changes can affect mobility and daily activities.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522951-24-00Protocol codeACT24-001Estimated enrolment108 patientsSponsorAngitia Inc. Ltd.

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