The ifosfamide/carboplatin/etoposide (ICE) combination represents an active chemotherapy regimen across a wide variety of disease types. The most common limiting toxicity for all three of these agents individually and in combination is myelosuppression. Thus, this regimen represents an ideal model to evaluate the role of hematopoietic growth factor support in amelioration of hematologic toxicity, maintenance of dose intensity, and dose escalation. While chemotherapy strategies using colony-stimulating factors have abrogated neutropenia, cumulative thrombocytopenia is common with many chemotherapy regimens, including ICE chemotherapy. In preclinical and phase II trials, monotherapy with recombinant human interleukin-6 (IL-6) has demonstrated substantial thrombopoietic activity, but with little enhancement of neutrophil recovery. Thus, this study was designed to evaluate combination cytokine therapy with both recombinant IL-6 and granulocyte colony-stimulating factor (G-CSF) after ICE chemotherapy. Previously untreated patients with inoperable non-small cell lung cancer are eligible. Treatment includes two monthly cycles of ifosfamide 2,000 mg/m2 with mesna 1,600 mg/m2 intravenously on days 1, 2, and 3, carboplatin 350 mg/m2 intravenously on day 1 only, and etoposide 75 mg/m2 intravenously on days 1, 2, and 3. All patients then receive G-CSF at a dose of 5 micrograms/kg/d subcutaneously beginning on day 4 until a postnadir absolute neutrophil count of more than 10 x 10(9)/L. Cohorts of patients (n = 15) are randomized to receive 0, 1, 2.5, or 5 micrograms/kg/d of IL-6 subcutaneously on days 4 to 13 in successive cohorts. This study has now reached its target accrual in all cohorts. The final data analysis is in progress. It is hoped that this trial will define the safety and tolerability of the simultaneous administration of IL-6 and G-CSF following ICE chemotherapy in patients with non-small cell lung cancer. In addition, this trial should determine the biologic activity and hematopoietic recovery observed during the simultaneous administration of these two cytokines in this setting.