Acquired haemophilia is a rare but serious bleeding disorder that can appear suddenly in people with no previous history of bleeding problems. Understanding how to manage this condition effectively can make a significant difference in outcomes and quality of life.

Understanding the Challenge of Acquired Haemophilia

When someone develops acquired haemophilia, their immune system begins producing autoantibodies, also called inhibitors, that mistakenly attack the body’s own clotting factors. These are special proteins that help blood clot normally and stop bleeding. In most cases, these antibodies target factor VIII, one of the most important clotting proteins in our blood. This condition is known as acquired haemophilia A.^[1]

The main goal of treating acquired haemophilia is to control bleeding episodes when they happen and to eliminate the harmful antibodies from the body. Unlike inherited haemophilia that people are born with, acquired haemophilia appears spontaneously in people who have never had bleeding problems before. This makes it particularly challenging because both patients and their families need to quickly adapt to managing a serious medical condition they knew nothing about until diagnosis.^[3]

Treatment approaches depend on several factors, including how severe the bleeding is, the level of antibodies in the blood, the patient’s age, and whether there are other medical conditions present. Some people with acquired haemophilia may experience only mild bleeding, while others face life-threatening hemorrhages that require urgent medical intervention. The variability in how the disease presents means that treatment must be carefully tailored to each individual patient.^[6]

Medical professionals have developed standard treatments that are recommended by haemophilia treatment guidelines around the world. At the same time, researchers continue to investigate new therapies through clinical trials, hoping to find even better ways to help patients manage this rare disorder. Both approaches—proven standard treatments and innovative experimental therapies—play important roles in caring for people with acquired haemophilia.^[6]

Standard Treatment Approaches

The standard treatment of acquired haemophilia has two main objectives that need to be addressed simultaneously. First, doctors must stop any active bleeding that is happening. Second, they need to eliminate the autoantibodies that are causing the problem. Both aspects are equally important because controlling bleeding saves lives in the short term, while removing antibodies prevents future bleeding episodes and leads to long-term recovery.^[1]

Controlling Active Bleeding

When a patient with acquired haemophilia experiences bleeding, standard treatments focus on providing substances that can bypass the missing or blocked clotting factors. One commonly used option is recombinant activated factor VII (rFVIIa), which works by activating the clotting process through a different pathway than factor VIII normally uses. This medication can be very effective at stopping bleeds even when antibodies are blocking the body’s natural clotting system.^[6]

Another important treatment option is activated prothrombin complex concentrate (APCC), which contains several activated clotting factors that work together to promote blood clotting. This mixture of clotting proteins can bypass the blocked factor VIII pathway and help the blood clot normally. Doctors choose between these options based on their availability, cost, and what has worked best for each individual patient.^[11]

A newer option that has become available is recombinant porcine factor VIII (rpFVIII). This is factor VIII derived from pig DNA, which is similar enough to human factor VIII to work in the body, but different enough that some patients’ antibodies may not recognize and attack it as readily. This treatment can be particularly useful for patients who have low levels of antibodies against the porcine form of the factor. However, it requires careful monitoring to ensure it remains effective, as some patients may develop antibodies against the porcine factor over time.^[4]

In some cases, when patients have very low levels of inhibitors (less than 5 Bethesda units), doctors might try using large doses of human factor VIII concentrate. However, this approach is less predictable because the antibodies present in the patient’s blood can neutralize the factor VIII that is being given. The doses required can be massive, and there are no standard guidelines for how much to use, making this a less preferred option when other treatments are available.^[11]

Eliminating the Harmful Antibodies

Once bleeding is under control, the focus shifts to eliminating the autoantibodies that caused the problem in the first place. This is achieved through immunosuppressive therapy, which means using medications that calm down or suppress the immune system. The goal is to stop the immune system from producing the harmful antibodies against factor VIII.^[6]

Corticosteroids are often the first line of immunosuppressive treatment. These are medications like prednisone that reduce inflammation and suppress immune activity throughout the body. Corticosteroids work by preventing immune cells from producing antibodies and can be effective on their own in many patients. However, they need to be used carefully because they can cause side effects, especially in elderly patients who are more vulnerable to complications like high blood sugar, high blood pressure, bone weakening, and increased risk of infections.^[9]

When corticosteroids alone are not sufficient, doctors often add cyclophosphamide, a more powerful immunosuppressive medication. Cyclophosphamide works by interfering with the DNA of rapidly dividing immune cells, preventing them from multiplying and producing antibodies. The combination of corticosteroids and cyclophosphamide has been used successfully in many patients and is considered a standard approach. However, cyclophosphamide can cause side effects including nausea, hair loss, decreased blood cell counts, and increased infection risk.^[6]

Rituximab is another important immunosuppressive medication that has become increasingly popular for treating acquired haemophilia. This is a monoclonal antibody, a type of engineered protein that specifically targets and destroys B lymphocytes, the immune cells responsible for producing antibodies. By eliminating these cells, rituximab can effectively stop the production of factor VIII inhibitors. Rituximab may be used alone or in combination with corticosteroids, and many doctors now prefer it because it can be very effective while potentially causing fewer side effects than some older medications.^[9]

The time it takes for immunosuppressive therapy to work varies considerably from person to person. On average, it takes about five weeks for the antibodies to disappear and for patients to achieve remission, meaning the antibodies are no longer detectable and factor VIII levels return to normal. However, some patients respond much more quickly, while others may take several months. During this time, patients need to be monitored closely with regular blood tests to check factor VIII levels and antibody titers.^[6]

In approximately 60 to 80 percent of patients, immunosuppressive therapy successfully eliminates the antibodies and leads to complete remission. However, some patients do not respond to initial treatment or may experience a relapse where the antibodies return after initially disappearing. These refractory or relapsed cases require more intensive or alternative immunosuppressive strategies, which may involve trying different combinations of medications or using second-line treatments.^[11]

Managing Underlying Conditions

In about half of patients with acquired haemophilia, the condition is associated with another underlying medical problem. These can include autoimmune diseases like rheumatoid arthritis or systemic lupus erythematosus, certain cancers, pregnancy and the postpartum period, or reactions to medications. When an underlying condition is identified, treating it appropriately or discontinuing the offending medication may help eliminate the inhibitor or make it easier to treat.^[1]

For women who develop acquired haemophilia during pregnancy or after childbirth, the condition often resolves on its own or responds well to treatment. However, careful monitoring and appropriate treatment are still essential during this period because bleeding complications can be serious. Treatment must be carefully balanced to protect both the mother’s health and, if she is still pregnant, the health of the baby.^[9]

Treatment in Clinical Trials

Because acquired haemophilia is a rare disorder, conducting large-scale clinical trials to compare different treatments has been challenging. Most of what doctors know about treating this condition comes from patient registries, case series, and clinical experience rather than from randomized controlled trials. However, researchers continue to investigate new approaches through clinical studies, hoping to find treatments that are more effective, easier to use, or have fewer side effects.^[6]

Novel Hemostatic Agents

One area of active research involves testing new hemostatic agents—medications that help control bleeding. While the bypassing agents like recombinant activated factor VII and activated prothrombin complex concentrate are well-established, researchers are exploring whether newer formulations or delivery methods might work better for some patients. Clinical trials examine optimal dosing strategies, compare the effectiveness of different agents, and look at which treatments work best for specific patient populations.^[10]

Emicizumab, a medication that has been successful in treating congenital haemophilia A with inhibitors, has generated interest as a potential treatment for acquired haemophilia A as well. Emicizumab is a bispecific antibody that mimics the function of factor VIII by bringing together two clotting factors (factor IXa and factor X) that normally need factor VIII to work together. This allows blood clotting to proceed even when factor VIII is missing or blocked by antibodies. Some clinical trials and case reports have explored using emicizumab in patients with acquired haemophilia, examining whether it can effectively control bleeding and possibly allow patients to avoid some of the side effects of traditional bypassing agents.^[4]

The advantage of emicizumab is that it is given by subcutaneous injection (under the skin) rather than intravenous infusion, and it only needs to be administered once weekly or even less frequently after a loading dose period. This could make it more convenient for patients and potentially useful for preventing bleeding episodes while immunosuppressive therapy is working to eliminate the antibodies. However, more research is needed to establish safety and effectiveness specifically in acquired haemophilia patients, who tend to be older and may have different medical needs than the younger patients with congenital haemophilia for whom emicizumab was originally developed.^[10]

Innovative Immunosuppressive Approaches

Clinical trials are also investigating new ways to suppress the immune system more effectively or with fewer side effects. Research focuses on finding the optimal combinations of immunosuppressive medications, determining the best doses and treatment durations, and identifying which patients might benefit from more aggressive therapy versus those who might respond to gentler approaches.^[10]

Studies have examined the timing and sequencing of immunosuppressive medications. For example, some clinical research has looked at whether starting with combination therapy (corticosteroids plus cyclophosphamide or corticosteroids plus rituximab) from the beginning leads to faster remission compared to starting with corticosteroids alone and adding other medications only if needed. These studies help doctors make evidence-based decisions about the most effective treatment strategies.^[9]

Researchers are also exploring the use of rituximab in various dosing schedules and combinations. Some clinical trials have tested using rituximab as first-line therapy rather than reserving it for patients who fail initial treatment with corticosteroids. Other studies have examined combining rituximab with different immunosuppressive agents to see if certain combinations are more effective at achieving rapid remission while minimizing side effects.^[10]

Biomarkers and Personalized Treatment

An important area of clinical research involves identifying biomarkers—measurable indicators in the blood or other tissues that can help predict which patients are more likely to respond to certain treatments or experience complications. For example, studies have shown that the type of antibody present (the antibody isotype), the initial factor VIII level at diagnosis, and the antibody titer can provide prognostic information about remission and survival.^[6]

Clinical trials are working to refine these prognostic markers so that treatment can be more personalized. The goal is to identify patients who might need more aggressive therapy upfront versus those who can be treated more conservatively, balancing the need to achieve remission quickly against the risks of treatment-related side effects. This is particularly important in acquired haemophilia because many patients are elderly or have other medical conditions that make them more vulnerable to complications from immunosuppressive therapy.^[10]

Registry Studies and Real-World Evidence

Given the rarity of acquired haemophilia, international patient registries play a crucial role in advancing knowledge about the disease. The European Acquired Haemophilia Registry (EACH2) has collected data on thousands of patients from across Europe and has provided valuable insights into the natural history of the disease, treatment patterns, and outcomes. Information from this and other registries has informed international consensus guidelines on diagnosis and treatment.^[6]

These registry studies function somewhat like observational clinical trials, allowing researchers to compare outcomes in patients treated with different approaches in real-world settings. While they do not have the same scientific rigor as randomized controlled trials, they provide valuable evidence about what works in everyday clinical practice, particularly for a rare condition where conducting traditional clinical trials is difficult.^[9]

Geographic Availability and Patient Eligibility

Clinical trials for acquired haemophilia are conducted at haemophilia treatment centers and academic medical centers in various countries around the world, including the United States, throughout Europe, and in other regions. The availability of specific trials varies by location and time, as studies are typically conducted in phases and may open and close enrollment at different times.^[10]

Patient eligibility for clinical trials depends on many factors, including the specific trial requirements, the patient’s age and overall health, whether they have received previous treatment, their antibody levels, and other medical conditions they may have. Some trials focus on newly diagnosed patients who have not yet received treatment, while others are designed for patients whose disease has not responded to standard therapies. Patients interested in participating in clinical trials should discuss this option with their haemophilia treatment center team, who can provide information about available studies and help determine eligibility.^[6]

Most Common Treatment Methods

• Hemostatic Therapy (Treatments to Stop Bleeding)
  • Recombinant activated factor VII (rFVIIa) – bypasses the blocked clotting pathway to help blood clot
  • Activated prothrombin complex concentrate (APCC) – contains multiple activated clotting factors that work together
  • Recombinant porcine factor VIII (rpFVIII) – pig-derived factor VIII that may not be recognized by human antibodies
  • High-dose human factor VIII concentrate – used in some patients with very low antibody levels
• Immunosuppressive Therapy (Treatments to Eliminate Antibodies)
  • Corticosteroids (such as prednisone) – suppress immune system activity and antibody production
  • Cyclophosphamide – powerful immunosuppressant that prevents immune cells from multiplying
  • Rituximab – monoclonal antibody that destroys B lymphocytes that produce harmful antibodies
  • Combination therapy – using two or more immunosuppressive medications together for better effect
• Supportive Care and Preventive Measures
  • Treatment of underlying conditions that may have triggered acquired haemophilia
  • Discontinuation of medications that may have caused the condition
  • Avoiding activities that increase bleeding risk until antibodies are eliminated
  • Regular monitoring with blood tests to check factor VIII levels and antibody titers