Chronic-Phase Chronic Myelogenous Leukemia
Clinical trials and long-term results from ongoing trials will be required before these controversies are resolved. Information about ongoing clinical trials is available from the NCI Web site.
Biologic therapy with or without chemotherapy
Long-term data are available for initial treatment with interferon alpha. A meta-analysis of seven trials that randomly assigned patients to receive interferon or conventional chemotherapy (hydroxyurea or busulfan) demonstrated a 30% reduction in the annual death rate for patients who received interferon (P < .001).[Level of evidence: 1iiA] The annual death rate was reduced by 26% in the trials of interferon versus hydroxyurea (P = .001) and 36% in the trials of interferon versus busulfan (P = .007). Median survival was prolonged by 1 to 2 years; 5-year survival rate was 57% for patients treated with interferon and 42% for patients treated with chemotherapy (P < .001). Further analysis of the two trials, which included a three-way randomization between interferon, hydroxyurea, and busulfan, showed hydroxyurea to be superior to busulfan, decreasing the proportional odds of death by 24% (P = .02). About 20% of the chronic-phase patients treated with interferon alpha have complete cytogenetic remissions with temporary disappearance of Philadelphia chromosome (Ph1)-positive cells in the marrow, and in about 10% of the patients these cytogenetic responses are quite long lasting.[40,41,42] These data have only been published in the context of a review article, rather than a peer-reviewed research manuscript.
Long-term follow-up of the interferon-treated patients from a randomized trial comparing interferon with chemotherapy showed that the median survival had not been reached at 10 years for patients who had complete or major cytogenetic responses to interferon. Seventy-four percent of patients with complete cytogenetic responses and 55% of patients with major cytogenetic responses were alive and had shown no disease progression at date of publication (median follow-up time was not provided). Using molecular methods of analysis, however, small numbers of Ph1-positive cells can still be detected in the majority of patients having long-term cytogenetic remissions, and longer follow-up will be required to ascertain whether the disease will recur.
Patients older than 60 years with chronic-phase CML have a hematologic and cytogenetic response rate and duration of cytogenetic response similar to that in younger patients; however, the incidence of complications is greater in elderly patients. Interferon alpha has significant toxic effects that can result in dosage modification or discontinuation of therapy in many cases. A randomized prospective trial of 407 patients compared two doses of interferon, 5 million units/m� daily versus 3 million units/m� daily; at a median follow-up of 53 months, no difference was seen in OS, progression-free survival, or number of major cytogenetic responses.[Level of evidence: 1iiA] As evidenced in the CLB-9013 study, common side effects included influenza-like syndrome, nausea, anorexia, weight loss, and neuropsychiatric symptoms, all of which were completely reversible with cessation of therapy. (Refer to the PDQ summaries on Nausea and Vomiting and Nutrition for information on some of these side effects.) Immune-mediated complications, such as hyperthyroidism, hemolysis, and connective tissue diseases may occur rarely after long-term treatment. Interferon alpha is quite costly, and daily subcutaneous injections can be troublesome. Pegylated interferon alpha is administered weekly; a randomized noninferiority trial of 344 newly diagnosed CML patients could not rule out the possibility that pegylated interferon alpha may be slightly inferior to daily interferon alpha.[Level of evidence: 1iiDiv]