High-dose interleukin-2 and interferon as first-line immunotherapy for metastatic melanoma: long-term follow-up in a large unselected Danish patient cohort

Background and patients: Between January 2007 and April 2014, 464 Danish patients received high-dose (HD) interleukin-2 (IL-2) and interferon (IFN) as first-line treatment for metastatic melanoma. Our data represent the largest cohort of patients with metastatic melanoma worldwide, with relevant data on all patients and no patients lost to follow-up. Data have been gathered in a national database on the treatment of metastatic melanoma established since 2011. Results: One hundred eighteen patients (25%) obtained an objective response rate (ORR) to treatment with a median progression-free survival (PFS) of 3.4 months and a median overall survival (OS) of 14.2 months. Furthermore, 2-, 3- and 5-year survival was 32.0%, 23.2% and 16.6%, respectively. Ipilimumab as second-line therapy has been used since July 2010. We divided patients in two subgroups before and after this date to evaluate the effects of new treatment strategies. Patient characteristics, ORR and PFS were comparable in the two subgroups. Survival was significantly improved after 2010, with an increase in median OS from 12.2 to 16.0 months and in 5-year OS from 12.5% to 20.7%. Conclusions: Our data confirm that HD IL-2/IFN as first-line therapy in metastatic melanoma leads to long-term survival in a subset of treated patients. Potentially, IL-2/IFN might represent a treatment option in patients with active melanoma after established initial treatment with checkpoint inhibitors and BRAF/MEK-targeted therapies.