Does continuous-infusion interleukin-2 increase survival in metastatic melanoma?

Pharmacy logbooks and clinical trial records were used to identify all 60 patients with metastatic melanoma who were treated as inpatients with intermediate-dose, continuous-infusion interleukin-2 (IL-2) in Hoag Hospital during 1987 to 1998. The hospital tumor registry was used to identify contemporary controls who had not received inpatient IL-2, matched for having distant metastatic melanoma, and by year and stage at original diagnosis, gender, and age. The mean time from original diagnosis to the documentation of distant metastatic disease was similar in both groups, 24 to 26 months. From the date of starting IL-2 therapy, patients had a median survival of 8.8 months, 38% 1-year survival, and 20% 5-year survival, with 8 patients alive beyond 5 years. However, there was no difference in survival from the first date of distant metastatic disease (median 25.8 months for IL-2 versus 31.5 months for controls, with survival rates 5 years after metastatic disease of 26% versus 31%). There was also no difference in overall survival from the date of original diagnosis (60.1 months for the IL-2 group versus 86.3 months for controls, with 5-year survival rates of 51% versus 64%, and 10-year survival rates of 29% versus 33%). This single-institution study failed to establish a survival advantage for patients with metastatic melanoma who received intermediate-dose, continuous-infusion IL-2 administered in the inpatient setting, compared to contemporary, matched-control patients who never received inpatient IL-2 therapy. However, the 5-year survival rates after a diagnosis of distant metastatic disease were a surprisingly high 26% to 31% in both groups. In the absence of a control group, the survival impact of IL-2 has probably been overestimated from single-arm phase II and III trials.