Research into new ways of treating Chronic Lymphocytic Leukemia is going on all the time. As no current treatments for leukemia cure all the patients treated, doctors dealing with the disease are continually looking for new ways to treat it. They do this by using clinical trials.

CRC Publications   Glossary

What is Chronic Lymphocytic Leukemia (CLL)?

Chronic Lymphocytic Leukemia is a type of cancer in which the bone marrow makes too many lymphocytes. Chronic Lymphocytic Leukemia (also called CLL) is a blood and bone marrow disease that usually gets worse slowly. CLL is the second most common type of leukemia in adults. It often occurs during or after middle age; it rarely occurs in children.

Normally, the body produces bone marrow stem cells (immature cells) that develop into mature blood cells. There are 3 types of mature blood cells:

  • Red blood cells that carry oxygen and other materials to all tissues of the body
  • White blood cells that fight infection and disease
  • Platelets that help prevent bleeding by causing blood clots to form

In CLL, too many stem cells develop into a type of white blood cell called lymphocytes. There are 3 types of lymphocytes:

  • B-lymphocytes that make antibodies to help fight infection
  • T-lymphocytes that help B-lymphocytes make antibodies to fight infection
  • Natural killer cells that attack cells with cancer or a virus

The lymphocytes in CLL are not able to fight infection very well. Also, as the amount of lymphocytes increases in the blood and bone marrow, there is less room for healthy white blood cells, red blood cells, and platelets. This may result in infection, anemia, and easy bleeding.

What causes CLL?

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the U.S. Moreover, the incidence rates of this disease appear to be on the rise. Genetic factors contribute to the development of this disease.

  1. First-degree relatives of patients with CLL are significantly higher risk for having this disease than is the general population.
  2. Afflicted individuals within such families often present at a younger age than most patients with CLL, suggesting that genetic factors in familial CLL contribute to early leukemogenesis.
  3. Environmental factors also have been implicated. In 2003, a committee of the US Institute of Medicine concluded that a positive association exists between exposures to herbicides used as defoliants from 1962 to 1971 during the Vietnam war and the risk of developing CLL
  4. The principal defoliant used by the US military forces in Vietnam was Agent Orange has been linked to a number of cancers including.  

An apparent increase in incidence of this disease also could be due in part to enhanced methods of early diagnosis, as diagnosis now is being made at earlier stages and in younger patients.  In one recent study, 3.5% of healthy persons over age 40 were found to have blood lymphocytes with the phenotype of CLL B cells that had apparent restriction in the use of immunoglobulin light-chains and immunoglobulin heavy-chain variable region gene subgroups.  Whether these cell populations represent a very early stage of indolent CLL remains speculative. 

Nevertheless, due to the advancing age of the U.S. population, the overall incidence rates of each stage of overt CLL appears to be increasing over time. Although the notion of an apparent increase in the incidence of CLL has been challenged by a more recent analysis of data from the Surveillance, Epidemiology, and End Results (SEER) program, this same study observed a notable lack of improvement in survival for patients with CLL when comparing the period 1974-1983 with 1984-1993.

What is a clinical trial?

If early work suggests that a new treatment might be better than the standard treatment, doctors will carry out studies to compare the new treatment with the best available standard ones. This is called a controlled clinical trial and is the only reliable way of testing a new treatment. Often several hospitals around the country take part in these trials.

In a randomized controlled clinical trial, some patients will receive the best standard treatment while others will receive the new treatment, which may or may not prove to be better than the standard treatment. So that the treatments can be compared accurately, the type of treatment a patient receives is decided at random - typically, by a computer - and not by the doctor treating the patient. This is because it has been shown that if a doctor chooses the treatment, or offers a choice to the patient, he or she may unintentionally bias the result of the trial. A treatment is better either because it is more effective against the disease or because it is just as effective and has fewer unpleasant side effects.

Before any trial is allowed to take place an ethics committee must have approved it. Your doctor must have your informed consent before entering you into a trial. This means that you know what the trial is about, you understand why it is being conducted and why you have been invited to take part, and you appreciate exactly how you will be involved. Even after agreeing to take part in a trial, you can still withdraw at any stage if you change your mind. Your decision will in no way affect your doctor's attitude towards you. If you choose not to take part or you withdraw from a trial, you will then receive the best standard treatment rather than the new one with which it is being compared. If you do choose to take part in a trial, it is important to remember that whatever treatment you receive will already have been carefully researched.

Clinical trials are conducted in four phases. Progressing to the next phase requires that researchers carefully study the results of the previous phase. Following is an overview of each phase of a clinical trial:

  • Phase I clinical trials are the first step in testing a new treatment in humans. Phase I clinical trials are designed to study how the human body reacts to the treatment and what side effects might occur at different dosages. Because Phase I trials may carry significant patient risk, only a small group of patients participate, and then only those who likely would not benefit from other treatments
  • Phase II clinical trials help researchers determine the safety and effectiveness of a treatment in patients with specific types of cancer. In other words, researchers are looking to answer this question: Does the new treatment have an anticancer effect?
  • Phase III involves large numbers of participants and helps researchers decide if a new treatment is as good as, better than, or inferior to the best available standard treatment. Phase III clinical trials compare the results of people taking a new treatment with the results of people taking the best available standard treatment
  • Phase IV trials involve thousands of people in the study of potential side effects that were not apparent in Phase III. Phase IV clinical trials are conducted after a treatment has been approved by the Food and Drug Administration (FDA) and is being marketed

Having a physician suggest a clinical trial does not necessarily mean that it's a last-resort treatment option for the patient. It simply means that the physician thinks society or the patient may potentially benefit from the treatment being studied.

Click here to view the CRC's current trials