Phase III trial of high-dose interferon alpha-2b versus cisplatin, vinblastine, DTIC plus IL-2 and interferon in patients with high-risk melanoma (SWOG S0008): An intergroup study of CALGB, COG, ECOG, and SWOG.

Abstract

8504 Background: High-dose interferon for one year (HDI) is the FDA approved adjuvant therapy for patients (pts) with high-risk melanoma (HRM). Efforts to modify IFN dose or schedule have not improved efficacy. A meta-analysis demonstrated that biochemotherapy (BCT) produced superior response rates compared with chemotherapy in pts with stage IV melanoma (Wheatley et al J Clin Oncol 25:5426, 2007). We sought to determine whether a short course of BCT would be more effective than HDI as adjuvant treatment in pts with HRM. Methods: S-0008 (an Intergroup Phase III trial) enrolled pts who were high risk (Stage III A-N2a thru Stage III C N3) and randomized them to receive either HDI or BCT consisting of dacarbazine 800 mg/m2 day 1, cisplatin 20 mg/m2/ days 1-4, vinblastine 1.2 mg/m2 days 1-4, IL-2 9 MIU/m2/day continuous IV days 1-4, IFN 5 MU/m2/day sc days 1-4, 8,10,12, and G-CSF 5 ug/kg/day sc days 7-16. BCT cycles were given every 21 days x 3 cycles (9 weeks total). Pts were stratified for number of involved nodes (1-3 v ≥4), micro v macro metastasis, and ulceration of the primary. Co-primary endpoints were relapse free survival (RFS) and overall survival (OS) using a one-sided log rank test at p= 0.05. Results: 432 pts were enrolled between 8/2000 and 11/2007: 30 were ineligible or withdrew consent. Grade 3 and 4 adverse events occurred in 57% and 7% respectively of HDI pts and 36% and 40% of BCT pts. At a median f/up of 6 yrs, BCT improved RFS (p = 0.02, HR 0.77 [90% CI: 0.62 – 0.96]) with median RFS for BCT of 4.0 yrs (90% CI:1.9 – 5.9) v 1.9 yrs (90% CI: 1.4 – 2.5) and 5 yr RFS of 47% v 39%. Median OS was not different between the two arms (p = 0.49 HR 1.0 [90% CI: 0.78 – 1.27]) with median OS not yet reached for BCT v 8.4 yrs (90% CI: 4.5 – 9.3) for HDI and 5 yr survival 56% for both arms. Conclusions: In HRM pts, BCT provides a statistically significant improvement in RFS compared to HDI, but no discernable difference in OS and more grade IV toxicity. BCT represents a shorter, alternative treatment for pts with HRM, and a potential control arm and basis for future combinations in the adjuvant setting.