According to results recently presented at the 43rd Annual Meeting of the American Society of Hematology, evidence suggests that combination chemotherapy versus interferon alone may improve responses but not survival in newly diagnosed patients with CML.
Chronic myeloid leukemia (CML), also called chronic granulocytic leukemia, is a cancer of the white blood cells. The bone marrow contains early blood-forming cells called stem cells, which grow and mature into 3 blood cell types: red blood cells, which provide oxygen to tissues; platelets, which aid in blood clotting; and white blood cells, which fight infection. In the case of CML, large numbers of young granulocytes (a type of white blood cell) do not mature, resulting in an excess accumulation of these cells. These leukemia cells then crowd the bone marrow and blood, suppressing formation and function of other blood cells normally present in these areas. In addition, the leukemia cells cannot perform their function in the body properly, leaving patients susceptible to infection.
CML begins with a chronic phase, during which few clinical problems, if any, present themselves. However, if left untreated, the chronic phase progresses into acute phases characterized by fast-growing and aggressive cancer. These phases are called the accelerated and blastic phases. Patients reaching these acute phases have a poor prognosis for long-term survival.
Interferon Alfa (IFNa) is a biological therapy used to stimulate the body’s own immune system to fight cancer and is one standard treatment option for patients with CML. Combination chemotherapy with IFNa has also shown anti-cancer activity, so research is ongoing to determine optimal treatment options for patients with CML.
The Italian Study Cooperative Group on CML recently conducted a clinical trial evaluating responses and survival of 528 patients with newly diagnosed CML treated with either IFNa alone or IFNa plus chemotherapy (low-dose Arabinosyl Cytosine, LDAC). Patients treated with the combination therapy achieved a hematological (blood) response of 62% at 6 months and cytogenetic (molecular response determined by a sensitive lab test called PCR) response of 28% in 24 months. Patients receiving IFNa alone achieved a hematological response of 55% at 6 months and a cytogenetic response of 18% at 24 months. The 5-year survival rate was 68% for patients treated with combination therapy and 65% for patients treated with IFNa alone.
These results indicate that anti-cancer response rates were slightly higher for patients receiving combination therapy versus IFNa alone. However, these results did not translate into enhanced long-term survival. More research is warranted to further define the efficacy of combination therapy for the treatment of newly diagnosed CML.
Patients with newly diagnosed CML may wish to speak with their physician about the risks and benefits of participating in a clinical trial evaluating IFNa alone or in combination with other promising therapies. Two sources of ongoing information regarding clinical trials include comprehensive, easy-to-use listing services provided by the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients. (Proceedings from the 43rd Annual Meeting of the American Society of Hematology, abstract #3035, Orlando, Florida, December, 2001)