Two different durations of adjuvant therapy with intermediate-dose interferon alfa-2b in patients with high-risk melanoma (Nordic IFN trial): a randomised phase 3 trial.

BACKGROUND: Adjuvant high-dose interferon alfa-2b improves relapse-free survival (RFS) in patients with high-risk melanoma, although benefits in overall survival are uncertain. Because of the toxic effects of high-dose regimens, intermediate doses are being explored. We investigated whether adjuvant therapy with intermediate-dose interferon alfa-2b for 1 or 2 years would improve outcomes in patients with stage IIB-IIC or III resected cutaneous melanoma.

METHODS: This randomised, open-label, phase 3, parallel-group trial was undertaken between 1996 and 2004. 855 patients were randomly assigned at 35 centres in the Nordic countries by block randomisation to three groups: observation only (group A); 4 weeks of induction (interferon alfa-2b 10 million units flat dose subcutaneously 5 days per week) followed by 12 months of maintenance therapy (interferon alfa-2b 10 million units flat dose subcutaneously 3 days per week; group B); or 1 month of induction and 24 months of maintenance (group C). Neither investigators nor patients were masked to treatment assignment. Patients were stratified for country and tumour stage; patients with stage III disease were further stratified for presence of metastatic lymph nodes at primary diagnosis versus at relapse, palpable versus non-palpable lymph-node metastases, and number of metastatic lymph nodes. The primary endpoint was overall survival in the two interferon alfa-2b groups combined. Analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01259934.

FINDINGS: 284 patients were assigned to group A, 285 to group B, and 286 to group C; all patients were analysed. The median follow-up time was 72·4 months (IQR 46·9-98·0). We recorded no significant improvement in overall survival in patients given interferon alfa-2b compared with observation: median overall survival was 56·1 months (IQR 22·3 to >120·0) in group A, 72·1 months (25·8 to >120) in group B, and 64·3 months (24·7 to >120) in group C (p=0·600). Hazard ratios (HR) for overall survival were 0·91 (95% CI 0·74-1·10; p=0·642) for groups B and C combined versus observation; 0·91 (0·72-1·14; p=0·652) for group B versus observation; and 0·91 (0·72-1·15; p=0·858) for group C versus observation. Median RFS was 23·2 months (IQR 5·6 to <120) in group A, 37·8 months (10·8 to >120) in group B, and 28·6 months (8·6 to >120) in group C (p=0·034). HRs for RFS were 0·80 (0·67-0·96; p=0·030) for groups B and C combined versus observation, 0·77 (0·63-0·96; p=0·034) for group B versus observation, and 0·83 (0·68-1·03; p=0·178) for group C versus observation. The most common grade 3 and 4 adverse events were fatigue (five in group A [1·8%], 28 in group B [9·8%], and 32 in group C [11·2%]), myalgia (three [1·1%], 15 [5·3%], 14 [4·9%], respectively), and thrombocytopenia (15 [5·3%], 23 [8·1%], eight [2·8%], respectively).

INTERPRETATION: Adjuvant therapy with intermediate-dose interferon alfa-2b did not significantly improve overall survival. Interferon alfa-2b with 1-year maintenance therapy significantly improved RFS, but we recorded no significant effect for 2-year maintenance therapy. Further research is in progress to define the subgroup of patients who benefit from adjuvant interferon alfa-2b.

FUNDING: Schering-Plough (now Merck); the Radiumhemmet Research Funds, Stockholm; the Stockholm County Council; and the Swedish Cancer Society.