January is Chronic Leukemia Month

Leukemia is a disease where there is an excess of malignant (cancerous) white blood cells in the blood and bone marrow. There are several forms of leukemia, each with a unique prognosis and treatment program. Chronic leukemia includes two separate diseases, Chronic Lymphocytic Leukemia (CLL) and Chronic Myelocytic Leukemia (CML).

Chronic Lymphocytic Leukemia

CLL is the most common form of all leukemia. It occurs most often in people more than 60 years old, however it can occur in younger adults. In CLL, there is an increase in the number of normal-appearing lymphocytes (a type of white blood cell) in the blood and bone marrow.

Patients may have enlarged lymph nodes, an enlarged spleen, and a decrease in red blood cells (anemia) or platelets.  They may be at greater risk of developing infections.

Most individuals first find out they have CLL when the disease is at an early stage, and many of these patients will require no therapy for the leukemia initially. Some will never require intervention for the disease, while others will get worse and require therapy. When the disease causes anemia, decreased platelets, infections, marked enlargement of lymph nodes or the spleen, therapy is required.

When therapy is required for patients with CLL, the age and overall health of the patient determines the drugs used.  For patients more than 65 years of age, oral chemotherapy (Chlorambucil) is often recommended. This medicine is well tolerated and improves problems for one half of patients treated. When patients are younger, or have greater problems resulting from CLL, Fludarabine, an intravenous chemotherapy drug is used.

Although these drugs can be effective in reducing problems from CLL, they cannot cure the disease. Eventually, blood problems, infections, enlarged lymph nodes and spleen will return, requiring consideration of more therapy. Subsequent treatment may involve chemotherapy, monoclonal antibody therapy (Rituxan and Campath), or even blood stem cell transplantation.

Monoclonal antibodies are proteins created in the laboratory, which attach to a specific protein that lives on the leukemia cell surface. When the monoclonal antibodies stick to the leukemia cell they trigger a process that can kill the cell. The monoclonal antibodies do not lower red blood cell or platelet counts as chemotherapy does. They do not cause hair loss or much nausea. However, the monoclonal antibodies can cause side effects, such as severe allergic reactions or dangerous infections (Campath). Rituxan and Campath have been used mostly in the setting of advanced CLL that has worsened after at least one course of treatment. Rituxan is often used in combination with chemotherapy.

Recently, research has focused on identifying patients who will develop dangerous problems sooner from the leukemia.  There are now blood tests, which can predict that a patient will face trouble in a few years rather than many years. For these high-risk patients, research is evaluating the incorporation of chemotherapy and monoclonal antibody treatment together as initial therapy. Hopefully, this will improve the outcome for this group of patients with CLL.

Fortunately, many patients with CLL will survive for a decade or more with the disease.  For those patients with problematic disease, consideration of more aggressive investigational therapy, such as blood stem cell transplantation or combined chemotherapy and monoclonal antibody therapy should be considered.

Chronic Myelocytic Leukemia

CML is an uncommon disease, where there is an increase in the number of granulocytes (a type of white blood cell in the blood and bone marrow). Most patients are found to have CML when a blood test is done for other reasons. Like CLL, many patients will be well when first diagnosed. But unlike CLL, if left untreated, the disease will usually become life threatening in a few years.

CML is caused by a break in two chromosomes (large pieces of genetic material) that results in a reshuffling of two genes to create a new gene. (A gene is a stretch of DNA that can produce protein-proteins, which make up the structure and function of our cells). The new protein created by the shuffling of chromosomal pieces leads to excessive growth of blood cells.

Until a few years ago, the only way to get rid of cells harboring this new protein was to treat patients with bone marrow or blood stem cell transplants from another donor. Stem cell transplants can cure many patients but are dangerous; in fact elderly patients have not been treated this way due to a high chance of death from the procedure.

Recently, Gleevec, a drug that fits like a key in the lock of the CML protein has revolutionized the care of CML patients. Elderly patients treated with Gleevec are now likely to survive much longer than before. Even younger patients are now receiving Gleevec first in hopes that they will never need a stem cell transplant.

We do not know if Gleevec will actually cure patients of CML, but most patients with early stage CML treated with the drug show no signs of the broken chromosome in their cells a few years into therapy. Patients who are 30 years old or younger are still encouraged to undergo stem cell transplantation soon after diagnosis, as these individuals face a smaller risk from the procedure relative to patients older than 40 years of age.

Some patients are first diagnosed with CML at a later stage when they have a big spleen, anemia, and a very high white blood cell count. Some of these patients will benefit from a stem cell transplant and others may get temporary benefit from Gleevec. In the last few years, transplant physicians have been studying a less aggressive type of stem cell transplant that hopefully will be less toxic (nonmyeloablative allogeneic stem cell transplant), thereby allowing older patients to benefit from the procedure.

If you have questions about Chronic Leukemia, e-mail us at info@nhoh.com.

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