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Researchers around the world are trying to better understand hairy cell leukaemia (HCL), improve its treatment and manage the treatment side effects. 

HCL a is rare and so there are fewer trials compared to some types of cancer. Some of the trials mentioned on this page are international and not recruiting people from the UK. Some of these trials have now stopped recruiting people. It takes time before the results are available. This is because the trial team follow the patients for a period of time and collect and analyse the results. 

We have included this ongoing research to give examples of the type of research being carried out in HCL.

Go to Cancer Research UK’s clinical trials database if you are looking for a trial in the UK. You need to talk to your specialist if there are any trials that you think you might be able to take part in. 


We don’t know what causes HCL. So doctors want to understand more about how and why it develops.

An American study in 2011 looked at blood samples from 47 people with HCL. The researchers found a genetic change (mutation) called BRAF V600E in all the people with HCL. They didn't find it in 195 people with other types of B cell lymphoma and leukaemia.

So from this study doctors know that this genetic change is important in the development of hairy cell leukaemia. But it is not clear why this change happens.

Identifying this genetic change might help with diagnosing and monitoring HCL. It has led to the development of drugs that target this genetic change. For example, vemurafenib (see treatment below).

Looking for gene changes

Scientists are looking at the abnormal lymphocyte cells found in the blood of people with conditions like hairy cell leukaemia. They are trying to understand how a particular gene helps these abnormal cells to survive.

As part of this study, you are asked to give samples of blood and bone marrow or tissue. You have these samples collected at the same time as your routine tests.  Taking part is unlikely to affect your treatment in any way. But the information from the study could help people with hairy cell leukaemia and other types of cancer in the future.


Targeted cancer drugs

Targeted cancer drugs work by targeting the differences in cancer cells that help them to grow and survive. Some of these drugs also work with the immune system to recognise and kill cancer cells.

Some studies have shown promising results with a drug called vemurafenib. It targets and blocks the V600E BRAF protein. It is called a BRAF inhibitor. Larger trials are now needed.

Trials have also looked at combining vemurafenib with another targeted drug called rituximab for some people with hairy cell leukaemia. Results suggests that the 2 drugs together are better than vemurafenib alone. Doctors already use rituximab to treat HCL.

Rituximab is a type of monoclonal antibody (MAB). MABs can recognise and target specific proteins found on the surface of cancer cells.

Diagram showing a monoclonal antibody attached to a cancer cell


Scientists can attach a toxin (a type of poison) to a monoclonal antibody. The antibody attaches itself to the protein on the leukaemia cell and delivers the toxin to the cell. The toxin then kills the cancer cell. These treatments are called immunotoxins.

Researchers in America are looking at an immunotoxin called BL22 and similar drugs which target proteins on the surface of hairy cell leukaemia cells.

These treatments have only been tested in a few people, so it is too early to know how well it works. More research is needed to look at the benefits and possible side effects.

Other targeted drugs

Researchers are looking at other targeted drugs either on their own, or in combination. For example, they are looking at:

  •  moxetumomab and rituximab for people whose HCL are come back (relapsed)
  •  ibrutinib for people with relapsed HCL 
  •  a combination of vemurafenib and obinutuzumab for people who have not yet had any treatment

The Hairy Cell Leukemia Foundation

The Hairy Cell Leukemia Foundation is based in the United States and funds a number of treatment trials for people with HCL. They run a Patient Data Registry that is open to researchers across the world. Through this registry they hope to gather information about as many people as possible with HCL. This should help them better understand this disease, why treatments may or may not work and more about the side effects.

Last reviewed: 
09 Dec 2019
  • Cancer Research UK Clinical Trials Database
    Accessed December, 2019

    Accessed December, 2019

  • New treatment options in hairy cell leukemia with focus on BRAF inhibitors
    B Falini and E Tiacci
    Haematological Oncology, 2019. 37 Supplement, pages 30 to 37

  • Vemurafenib Plus Rituximab in Hairy Cell Leukemia: A Promising Chemotherapy-Free Regimen for Relapsed or Refractory Patients
    E Tiacci and other
    Blood, 2016. Volume 128, issue 22, page 1214

  • Hairy cell leukemia: Update on molecular profiling and therapeutic advances
    M Grever and others
    Blood Reviews, 2014. Volume 28, Issue 5

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact with details of the particular issue you are interested in if you need additional references for this information.