Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults, and has been called the classical leukemia of the elderly. It differs from chronic myelogenous leukemia (CML) in that different types of white blood cells are affected, and different drugs are used for chemotherapy. The “chronic” designation implies a long survival time, but this varies widely for different patients. Aggressive disease may produce a survival time of only a few months, while patients with indolent disease have a virtually normal life expectancy.
There is a long list of drugs used to treat CLL, each with different trade-offs between effectiveness and toxicity. The cytostatic agent class of drugs includes chlorambucil, fludarabine, pentostatin, cladribine, cyclophosphamide, doxorubicin, vincristine, prednisone, and bendamustine. Monoclonal antibodies include rituximab, alemtuzumab, lumiliximab, and ofatumomab. These are all proteins which must be injected. Other drugs include mitoxantrone, oblimersen, lenalidomide, and flavopiridol. Chlorambucil has been considered a “gold standard”, and still has many advantages for elderly patients, including low toxicity, low cost, and convenience as an oral drug. A recent article reports 90 percent overall response to drug treatment, with almost 50 percent complete remission.
Recurrent CLL is defined as disease progression after at least six months in patients who had achieved complete remission or partial response. Refractory CLL is a more serious condition, in which the patient does not respond to therapy or experiences disease progression in less than six months. These cases can be treated with more aggressive drug therapy, or with a bone marrow transplant.
As in all transplants, bone marrow transplants carry the risk of graft versus host disease. Matched donors are preferred, and there are national and international registries of donors. Research continues into using hematopoietic stem cells from the donor's peripheral blood, or even cells collected from the patient's own blood and then cultured.
Before the leukemia patient receives a bone marrow transplant, he or she first undergoes a myeloablative procedure to destroy the diseased bone marrow with drugs or radiation. This is called “conditioning”. A newer technique is called reduced-intensity conditioning, and has improved the outcomes. A combination of transplantation and immunomanipulation with drugs can be used when the primary treatment drugs are not effective.
References:
1. Hallek M, “State-of-the-art treatment of chronic lymphocytic leukemia”, Hematology Am Soc Hematol Educ Program. 2009: 440-9.
2. Motta M et al., “Chronic lymphocytic leukemia: Treatment options for patients with refractory disease”, Cancer. 2009 Sept. 1; 115(17): 3830-41.
3. Holowiecki J, “Indications for hematopoietic stem cell transplantation”, Pol Arch Med Wewn. 2008; 118(11): 658-63.
4. Bone marrow donors registry:
http://www.marrow.org/
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.