Hairy cell leukaemia research

We must fully research all potential new treatments before we can adopt them as standard treatment for everyone. This is so that

• We can be sure they work
• We can be sure they work better than the treatments that are available at the moment
• We know they are safe

First of all, treatments are developed and tested in laboratories. For ethical and safety reasons, experimental treatments must be tested in the laboratory before they can be tried in patients. If a treatment is said to be at the laboratory stage of research, it is not ready for patients and is not available either within or outside the NHS.

Tests using patients are called clinical trials. The trials and research section has information about what trials are including information about the 4 phases of clinical trials. As hairy cell leukaemia is a rare cancer, it is more difficult to do trials. Talk to your doctor if you are interested in a new treatment and they will be able to tell you if it is appropriate for you. All the new approaches covered here are the subject of ongoing research. Until studies are completed and new effective treatments are found, these potential new treatments cannot be used as standard therapy for hairy cell leukaemia.

Because it is a rare cancer, there are fewer clinical trials for hairy cell leukaemia than for more common types of cancer. It is hard to organise and run trials for rare cancers, and it can take a long time to recruit the number of patients needed. Getting enough patients is critical to the success of a trial. If the trial is too small, the results won't be powerful enough to prove that one type of treatment is any better than any other.

Doctors diagnose hairy cell leukaemia by looking at the blood and bone marrow biopsy under a microscope. These tests use chemical stains to show up different cells. Doctors have recently developed a new way to do this. It is called immunohistochemical (IHC) staining. IHC makes it easier to spot differences between hairy cell leukaemia and other blood diseases. The test can also identify hairy cell leukaemia - variant (HCL-V). This is a rare type of HCL which tends not to respond as well to standard HCL treatments.

This test may also be useful in finding any cells that remain after treatment. Doctors call this minimal residual disease (MRD). We know that treating people who have MRD before they have symptoms doesn’t improve their outlook. But learning more about which people with MRD have disease that comes back and which don’t, may help doctors know more about how well treatments work.

Doctors are researching the use of biological therapy for hairy cell leukaemia. Monoclonal antibodies are proteins made by normal cells of the blood and immune systems when they come across infection. Our bodies make many different antibodies as part of our immune system’s reaction to infection or damaged cells. Each antibody recognises one specific protein that is found on the surface of an invading cell (bacteria or virus).

A monoclonal antibody (MAB) is a single antibody made in the lab that can be produced in bulk. 'Monoclonal' just means 'all one type'. There are MABs that can recognise particular proteins found on the surface of cancer cells. MABs being tested for HCL are

• Rituximab
• Immunotoxin treatment

Rituximab

This is a type of MAB mostly used to treat non Hodgkin’s lymphoma. Early trials have found that it can help control hairy cell leukaemia in some patients. Rituximab targets a protein on the surface of the leukaemia cell called CD20. The body’s immune system recognises this protein and attacks it.

For HCL, it is usual to have rituximab and chemotherapy as a combined treatment. Reports from small studies are encouraging. But we need more research to find out how useful this will be as a treatment for HCL.

Because HCL is so rare, it is difficult to conduct large randomised controlled trials. So doctors are already using it to treat HCL

• That has come back a second time, after treatment with chemotherapy
• Did not respond to chemotherapy after it had relapsed

You can find information about rituximab for HCL in the page on treatment for HCL that comes back.

Immunotoxin treatment

This treatment uses a toxin (a type of poison), attached to a monoclonal antibody, to kill the cancer cell. The antibody targets one specific protein on the cancer cell. It attaches itself to the protein and delivers the toxin to the cell. The toxin then kills the cancer cell.

Research in the USA has looked at an antibody called BL22 which targets the protein CD22. This is one of the proteins on the surface of hairy cell leukaemia cells. A small trial in the USA showed that it may be a useful treatment for hairy cell leukaemia. But we need more research to find out more about how well it works and what the side effects are.

There is a study looking at the abnormal lymphocyte cells that are found in the blood of people with diseases like hairy cell leukaemia. Scientists are trying to understand how a particular gene helps these abnormal cells to survive. You may be asked to give a blood sample to help with this study. It 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.