Infectious complications associated with interleukin-2 administration: A retrospective review of 935 treatment courses

Purpose: To determine if interteukin-2 (IL-2)-treated patients are prone to develop clinically significant infections, a retrospective review of 519 patients who received 935 treatment courses over a 38-month period was conducted. Materials and Methods: Treatment records of patients receiving intravenous (IV) bolus IL-2 were reviewed. Clinically significant infectious episodes were identified by retrieving data on antibiotic usage and cross-referencing this with microbiology records and chart review. Results: One hundred thirty-nine documented infectious episodes occurred in 122 treatment courses (13.0%); 11 courses were associated with more than one episode of infection. Predominantly urinary tract infections (6.8%) and infections related to IV catheters (5.3%) were encountered. Fifty-eight percent of the catheter-related infections were associated with bacteremia. Other infections included respiratory tract infections (1.0%), skin/muscle infections (0.9%), and miscellaneous infections (0.9%). Bacteria were isolated from the ma-jority of infections. Almost all patients were successfully treated for their infection, with only two septic deaths (0.2%). No difference was noted in infected versus noninfected patients with regard to diagnosis or previous therapy. There was a significant tendency for those patients who developed infection to be older (P₂ = .002, Mantel test for trend). Risk factors for the development of infection included vascular access catheters, open wounds, biliary obstruction, or incomplete treatment of previous infections. Over the 3-year study period, the incidence of infection declined from 23% to 7% (P₂, < .0001, Mantel test for trend) due to rigorous patient screening, vigilant monitoring for infection, liberal use of antibiotics for suspected infection, and use of prophylactic antibiotics for central venous catheter placement. Conclusion: Although treatment with IL-2 may be associated with a slightly increased incidence of bacterial infections, these infections can be successfully managed in the great majority of cases.