What to Expect in a Clinical Trial

Understanding the ins and outs of clinical trials will help you make an informed decision.

You are considering a clinical trial. What’s next?

Below is an overview of some considerations when thinking about participating in a clinical trial. Take the time to discuss the idea with your loved ones and understand everything it entails. There are multiple investigational gene therapy clinical trials for hemophilia currently underway, and each one is different. Having discussions with your healthcare team about eligibility criteria and specific trial expectations will help inform your decision.

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Clinical trial considerations

Informed consent

Timing of enrollment

Trial locations

Time commitment

Testing and follow-up

Informed consent

Informed consent is a two-way conversation between you and a clinical trial’s research team.

Topics you will discuss:

  • The facts about the trial, obligations of participation, and known and potential safety risks
  • Trial timeline
  • Impact on current care
  • The right to withdraw from a trial at any time
  • Any other questions you have

Ask and understand details about the clinical trial before consenting to participate.

Screenings may be required

Before beginning a clinical trial for hemophilia, potential participants are screened to determine who is eligible (inclusion criteria) or ineligible (exclusion criteria). Because clinical trials differ, they typically have different screenings. That means if you are not eligible for one clinical trial, you may still be eligible for another.

Click on some of the common screenings for a hemophilia gene therapy clinical trial to learn more:

In general, adeno-associated virus (AAV) gene therapy clinical trials for hemophilia have focused on enrolling adults. Often, clinical trials will start enrollment for an adult population before enrolling adolescents or children. An additional consideration in hemophilia gene therapy research is that a younger person’s liver may still be growing. It is unknown if the effect of the new functional gene delivered through gene therapy could be reduced as the liver continues to grow.

In hemophilia, disease severity is classified by the amount of naturally occurring clotting-factor activity in the body. To date, most clinical trials have restricted enrollment to only those people who have less than or equal to 1-2% clotting-factor activity.

The presence of inhibitors or having a history of inhibitor activity may affect eligibility in different gene therapy trials for hemophilia. Talk with your doctor about which one may be right for you.

Each clinical trial may have different enrollment criteria as they relate to other medical conditions, including HIV, active hepatitis C infection, and overall health of the liver.

A common screening specific to gene therapy clinical trials for hemophilia is for preexisting neutralizing antibodies, commonly called NAbs. NAbs indicate prior exposure to the AAV used in gene therapy research. If they are present, you may not be eligible for the clinical trial.

Those are just some of the screenings a gene therapy clinical trial for hemophilia may review. Every clinical trial is different, so you should talk with your doctor and healthcare team if you are considering participating in one.

Understanding immune response

Another important aspect of gene therapy clinical trials for hemophilia is understanding the body’s immune response.

  • There are differences in preventing, preparing for, or managing possible immune responses:
    • One approach is the use of immunosuppression or immunomodulatory drugs (i.e., steroids or other drugs that suppress the immune response and may help manage possible side effects).
    • These drugs may be given before gene therapy infusion, after infusion, or both.
    • If considering a clinical trial, make sure you understand what medications may be needed to participate, and for how long, and what potential side effects you may face.

Learn more about how gene therapy research considers the immune system in its delivery.

Before, the day of, and after receiving gene therapy

All clinical trials carefully follow specific instructions and guidelines, informed by preclinical research. These guidelines are in place to ensure the safety of trial participants and to maintain consistency for the research team, allowing them to understand the outcomes of the clinical trial.

Every clinical trial is unique, so discuss the specifics of each trial with your healthcare team. Outlined below are some common elements to help provide an idea of what to expect.

There may be an observational period prior to dosing day:

  • This provides an understanding of your current treatment and experience living with hemophilia prior to gene therapy.
  • This helps establish a baseline of information to compare with the impact of the gene therapy.

  • A health check is usually conducted.
  • The infusion typically takes about an hour.
  • You may be required to stay at the study site overnight or return the next day for some tests.

There will be defined time frames for follow-ups after treatment day for continued monitoring. The follow-up is important to fully understand the safety and effectiveness of a gene therapy. Here’s a general overview of what that could look like:

  • Over the first few months, there will be blood draws and follow-up appointments to monitor your well-being and collect information about the impact of gene therapy. These will become less frequent over time.
  • It is encouraged to enroll in a long-term follow-up study or registry to help researchers understand the efficacy and safety of gene therapy for years to come.

What’s being measured in these follow-ups?

  • Assessment measures, or endpoints, are used to measure safety and efficacy. These may be different in clinical trials.
  • Some examples of endpoints in investigational gene therapy clinical trials for hemophilia include:
    • Bleeding episodes or ABR (annual bleed rate): how many occur
    • Factor infusions: how many may be needed after gene therapy administration
    • Duration: how long a specific blood-clotting factor is produced

Learning more

If you’re interested in learning more about gene therapy clinical trials for hemophilia, speak with your physician and visit ClinicalTrials.gov.

Frequently asked questions

  • Investigational gene therapy aims to address a genetic condition at its source—the gene.
  • One gene therapy approach uses viral vectors, which act as a delivery vehicle to bring the new gene into a cell.

The adeno-associated virus (AAV) is commonly used as a vector in gene therapy research overall, and specifically in gene therapy research for hemophilia. Learn more about AAV gene therapy for hemophilia.

Learn more about AAV gene therapy for hemophilia.

The primary research goal is to evaluate the safety and effectiveness of gene therapy intended to deliver a functional gene. Investigational gene therapy for hemophilia is designed to add a functional copy of the factor VIII or factor IX gene to a cell’s command center (nucleus). If transferred successfully, the functional gene is intended to provide the cell with the instructions to make factor VIII or factor IX clotting protein.

Learn more about the process.

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