Effect of recombinant human interleukin-3 on haematological recovery from chemotherapy-induced myelosuppression

Summary. Patients with non-small-cell lung cancer (NSCLC) were treated with ICE chemotherapy (ifosfamide 2000 mg/m², days 1-3; carboplatin 300 mg/m², day 1; etoposide 75 mg/m², days 1-3) intravenously (i.v.) during the first 3d of a maximum of four 28 d treatment cycles. Interleukin-3 (IL-3) was administered in cycles 2 and 4 as a daily subcutaneous (s.c.) injection on days 5-18. Cohorts of three patients were treated at dosage levels of 0.5, 1.25, 2.5, 5.0, 10.0 and 15.0 μg/kg/d. At 15.0 μg/kg/d a 'flu-like' syndrome of myalgias, arthralgias and fatigue was considered dose-limiting. Other toxicities were headache, fever, urticaria, arrhythmia, chills and flushing. Subsequently, nine patients were added to the group receiving 10 μg/kg/d. 27 patients received IL-3 after their second course of ICE. At 10 and 15 μg/kg/d, IL-3 in cycle 2 was associated with enhanced haematological recovery. Depth of neutrophil nadir and days of neutropenia (ANC < 0.5 × 10⁹/1) were reduced in 9/13 patients and in 8/11 patients, respectively. No effect was seen on platelet nadir or days of thrombocytopenia. IL-3 was well tolerated up to 10 μg/kg/d when given as a daily s.c. injection. Results suggest IL-3 as a potential adjunct to chemotherapy, and further studies to explore administration of IL-3 in combination with other cytokines in this setting are warranted.