|  |  |  | | | | STRONG IMMUNE SYSTEM HELPS BEAT LEUKAEMIA | | | | |
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Release Date: 20th June 2002
A strong immune system is as important in patients who recover from leukaemia as their treatment, scientists reveal in research published today.
The critical role the immune system appears to play in keeping patients in remission after chemotherapy is reported in the British Journal of Haematology*.
The work may allow doctors to test the strength of a patient’s immune system and pick out those who are destined to relapse long before it becomes a clinical problem.
Giving these patients treatment to boost their immune system - possibly by a vaccine - could ultimately save their lives, researchers suggest.
Dr Mark Lowdell, a Leukaemia Research Fund supported scientist at the Royal Free Hospital, London, said: “Our findings propose that it is the immune response, rather than the chemotherapy per se, which is responsible for continued remission. The measurement of a patient’s immune response to their leukaemia when they have completed their therapy may be used as an indicator or risk of subsequent relapse.”
Dr Lowdell and his team headed by Professor Grant Prentice studied 25 leukaemia patients who went into remission following chemotherapy or bone marrow transplantation. They assessed how powerfully the patients’ immune system responded to leukaemia cells - by mimicking the encounter between immune cells and the cancer cells.
They then calculated the percentage of leukaemia cells that were successfully killed. Dr Lowdell believes this proportion has to be above a certain threshold to keep patients in remission.
The patients were monitored for over eight years, and the researchers found that all patients who relapsed had immune responses below the threshold. All of the adult patients and half of the children who remained in remission had anti-leukaemia responses that exceeded the threshold. The researchers conclude that the immune system plays a vital role in keeping cancer at bay.
The work has been funded by the Leukaemia Research Fund, Association of International Cancer Research and the Foundation for Children with Leukaemia. Cancer Research UK scientists and researchers at the Department of Haematology, Colchester General Hospital also collaborated on the pioneering project.
Dr Lowdell said: “Initially leukaemia overwhelms the immune system, making it impossible for it to fight back, and the patient gets sick. We can counter the attack with chemotherapy that devastates the diseased cells but it probably doesn’t eradicate them completely. Some patients then appear to make an immune response to the leukaemia.
“It is clear from our research that the strength of this counter attack by the immune system is absolutely vital to the patient’s sustained good health. These are preliminary results, but they are very exciting.
“If the results are replicated in larger-scale studies we will have a simple, easy-to-perform test to accurately predict whether patients will remain in remission or whether they are likely to relapse.”
The likely treatment at present for patients facing relapse is a bone marrow transplant, but as research in this area continues Dr Lowdell believes it will be possible to stimulate their immune systems to kill the cancer cells.
Dr David Grant, Scientific Director of the Leukaemia Research Fund, which helped fund the study, said: “We have known for some time that leukaemia is vulnerable to cells from the immune system, but never has it been reported so clearly or linked so closely to relapse. Learning to harness this is the next challenge and work is already underway. As our knowledge of the immune system unfolds we hope to be able to switch on its cancer-killing capabilities as and when required.”
*Evidence that continued remission in patients treated for acute leukaemia is dependent upon autologous natural killer cells, British Journal of Haematology, Volume 117, Issue 4, 20th June 2002.
 | Notes for editors |
image!!!
The black and white image shows a patient’s natural killer (NK) cells attacking her acute myeloid leukaemia (AML).
The colour image is of NK cells (small blue nuclei) attacking an autologous AML cell. It shows that CD69 (green) is involved in the signalling process leading to the killing. This is the first evidence that CD69 has a physiological role in NK cell-killing and shows that its ligand (target - currently unknown) is expressed on AML cells. Ultimately, this may be one way of boosting the immune system to fight leukaemia.
 | The scientists analysed immune response in 25 patients with acute leukaemia who were in first remission after chemotherapy and/or bone marrow transplant. They looked at a range of patients - adults and children - who were diagnosed with either acute myeloid leukaemia (AML) or acute lymphoblastic leukaemia (ALL). |
| Blood samples were tested for the presence of immune cells called natural killer (NK) cells. Researchers then used laboratory techniques to analyse the percentage of the patient’s leukaemia cells successfully killed by their natural killer cells. This was termed leukaemia cytolytic activity (LCA) . They found that the overwhelming majority of patients whose NK cells killed more than 12% of their cancer cells stayed in remission for a period of more than 2 years. |
| The concept of immunotherapy is to use the body’s own disease fighting soldiers - so-called natural killer cells - to attack cancer cells. LRF researchers are looking at ways to teach the immune system to fight different forms of leukaemia and lymphoma. This work has grown out of a new understanding of how of our immune system reacts to cancer cells. |
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