Immune-mediated and unusual complications during interferon alfa therapy in chronic myelogenous leukemia.

PURPOSE Long-term treatment with interferon alfa (IFN alpha) can produce or exacerbate immune-mediated complications (IMC). The purpose of this study was to analyze the experience with IMC and unusual complications in patients with chronic myelogenous leukemia (CML) undergoing IFN alpha treatment. PATIENTS AND METHODS The occurrence of IMC and unusual complications was evaluated in patients with Philadelphia chromosome (Ph)-positive CML. RESULTS Well-documented and clinically evident complications developed in 35 patients after a median of 14 months of IFN alpha treatment. These included 28 (5%) of 581 patients with Ph-positive CML treated with IFN alpha-containing regimens at M.D. Anderson Cancer Center (MDACC) and seven patients referred for opinion or problems who were on other studies. Hypothyroidism occurred in 11 patients (2%), immune-mediated hemolysis in seven (1%), and connective tissue diseases in 11 (2%). Other unusual occurrences included congestive heart failure (CHF; n = 4), porphyria cutanea tarda (PCT; n = 3), membranous glomerulonephritis (MGN; n = 1), and vitiligo (n = 1). IFN treatment was discontinued in 19 patients and the dose was reduced in five. Ten of 11 patients (91%) with immune-mediated hypothyroidism and eight of 11 (73%) with connective tissue diseases had some degree of cytogenetic response at the time of the event. CONCLUSION Although the frequency of IMC is low, patients treated with IFN alpha should be monitored for signs and symptoms of autoimmunity.