Abstract 4692: Local adjuvant treatment of clinical stage I-II melanoma with low dose CpG-B and/or GM-CSF: Long-term follow-up of three randomized controlled phase II trials

Abstract

Abstract Introduction: Currently, there is no widely used adjuvant treatment available to improve survival after surgical excision of localized melanoma. Here, we present the clinical outcome of patients who participated in three randomized phase-II trials and received low-dose local immunotherapy, which was shown to be safe and to boost loco-regional and systemic anti-melanoma T cell immunity. Patients and Methods: In three single-center, single-blinded, randomized and placebo (saline) controlled phase-II clinical trials, patients with early stage melanoma were treated with 1) Granulocyte/Macrophage-Colony Stimulating Factor (GM-CSF), 2) unmethylated CpG type-B oligodeoxynucleotide CpG7909 (CpG-B), and 3) CpG-B, alone or combined with GM-CSF, through 1-4 intradermal injections at the site of the primary melanoma excision scar, within 7 days preceding re-excision and sentinel lymph node (SLN) biopsy. For clinical follow-up analysis, all treated patients were grouped together (treated group n=36) as were the patients who received saline (saline group n=28). Results: 10-year recurrence-free survival rate in the treated group was 94% (95% CI 78-98) versus 48% (95% CI 21-71) in the saline group (P=0.005), hazard ratio (HR) for recurrence was 0.15 (95% CI 0.06-0.60) for the treated group. This apparent antitumor efficacy was in line with the observation upon pathological examination of less tumor positive SLN in the treated group (P=0.05). The 10-year distant recurrence-free survival rate in treated patients was also higher (94%, 78-98 versus 59%, 28-81, HR 0.22, 0.07-0.93; P=0.04). Conclusion: Local low-dose immunotherapy in patients with early-stage melanoma may offer durable protection against distant recurrences. These findings warrant further clinical exploration of this local non-toxic immune potentiating regimen. Citation Format: Bas D. Koster, Mari F. van den Hout, Berbel J. Sluijter, Barbara G. Molenkamp, Ronald J. Vuylsteke, Arnold Baars, Paul A. van Leeuwen, Rik J. Scheper, Monique P. van den Tol, Alfons J. van den Eertwegh, Tanja D. de Gruijl. Local adjuvant treatment of clinical stage I-II melanoma with low dose CpG-B and/or GM-CSF: Long-term follow-up of three randomized controlled phase II trials [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4692. doi:10.1158/1538-7445.AM2017-4692