Abstract
BACKGROUND: Interleukin 2 (IL-2) is a growth factor for T and natural killer cells, promotes proinflammatory cytokines, and can lead to durable responses in patients with melanoma. Vascular endothelial growth factor (VEGF) promotes angiogenesis and modulates host innate and adaptive immunity. High VEGF levels were found to be associated with nonresponse to IL-2. Ziv-aflibercept may deplete VEGF and thereby enhance antitumor T-cell responses, thus supporting a combination immunotherapeutic strategy with IL-2. METHODS: NCI 8628 was a phase 2 trial of ziv-aflibercept and IL-2 (arm A) versus IL-2 alone (arm B) randomized at 2:1, respectively. Eligible patients had inoperable American Joint Committee on Cancer stage III or stage IV melanoma. The primary endpoint was progression-free survival (PFS). RESULTS: A total of 89 patients were enrolled and 84 patients were treated. The median follow-up was 41.4 months. Among treated patients (55 patients in arm A and 29 patients in arm B), PFS was significantly improved in favor of arm A, with a median of 6.9 months (95% confidence interval [95% CI], 4.1-8.7 months) versus 2.3 months (95% CI, 1.6-3.5 months) (P<.001). No significant difference was noted with regard to overall survival, with a median of 26.9 months (95% CI, 14.4-63.6 months) for arm A and 24.2 months (95% CI, 11.3-36.4 months) for arm B. The response rate (according to Response Evaluation Criteria In Solid Tumors [RECIST]) was 22% in arm A (4 complete responses [CRs] and 8 partial responses [PRs]) and 17% in arm B (1 CR and 4 PRs). Stable disease or PR or CR was noted in 65% of patients in arm A and 48% of patients in arm B. The combination was found to be superior to monotherapy in patients with high and low levels of serum VEGF and VEGF receptor 2. Adverse events were consistent with the expected profiles of monotherapy with IL-2 and ziv-aflibercept. CONCLUSIONS: Ziv-aflibercept and IL-2 were found to significantly improve PFS compared with IL-2 alone, thereby meeting the primary endpoint of the current study. These findings support further study of immunotherapeutic combination strategies involving VEGF inhibitors.