The objective of this ongoing trial is to study the ability of darbepoetin alfa to reverse chemotherapy-induced anemia in cancer patients, and to relate improvement in hemoglobin with changes in fatigue and functional capacity. Eligible subjects had a nonmyeloid malignancy, were receiving multicycle chemotherapy, and were anemic, as defined by a screening hemoglobin < or = 11 g/dL. Darbepoetin alfa was administered at a starting dosage of 3 microg/kg every 2 weeks for up to eight doses (16 weeks) in an open-label, noncomparative setting. A total of 194 oncology practices contributed 1,173 subjects to this interim analysis. The mean increase in hemoglobin was 1.7 g/dL (95% CI: 1.6, 1.8) to last value on study (intent-to-treat analysis) and 2.1 g/dL (95% CI: 1.9, 2.2) for those patients receiving the full 16 weeks of therapy. The Kaplan-Meier estimate of the proportion of subjects with a hematopoietic response (increase in hemoglobin > or = 2 g/dL and/or hemoglobin value > or = 12 g/dL) was 84% (95% CI:81,86). Subjects in the lower baseline hemoglobin category (< 10 g/dL) tended to have a greater hemoglobin response during treatment. The Functional Assessment of Cancer Therapy-Fatigue (FACT-Fatigue) subscale score increased by a mean of 6.8 points (26%) during the study, and improvements in fatigue paralleled the increases observed in hemoglobin. Study treatment-related toxicity was minimal, with the most common event being injection-site pain, seen in 2% of subjects. Experience to date with an every-2-week regimen of darbepoetin alfa indicated efficacy comparable to historical experience with weekly and 3-times-weekly regimens of epoetin alfa in treating chemotherapy-induced anemia in cancer subjects.