Abstract LB-157: IL-12p70 producing dendritic cell vaccine elicits Tc1 polarized T cells and extends time to progression in metastatic melanoma.

Abstract

Abstract Systemic administration of IL-12p70 has demonstrated clinical activity in cancer patients but dose-limiting toxicities have hindered its incorporation in vaccine formulations. In this proof-of-concept phase I clinical trial (NCT00683670), we report on the immunological and clinical outcomes upon vaccination of newly diagnosed stage IV melanoma patients with CD40L/IFN-γ matured IL-12p70 producing dendritic cells (mDC). HLA-A*0201+ individuals with treatment naïve metastatic melanoma were vaccinated with mDC pulsed with melanoma gp100-derived peptides, every 3 weeks by intravenous infusion for six doses, after a single dose of cyclophosphamide (300 mg/m2 iv). CT imaging was performed at baseline, week 9 and 18 for clinical assessment using RECIST. PBMC were taken weekly for immune monitoring by tetramer analysis and functional assays. Six of seven treated patients develop sustained T cell immunity to all three melanoma gp100 antigen-derived (G154, G209-2M and G280-9V) peptides, while one patient had transient immunity only to the G209-2M peptide. Three of the six immunological responders developed a radiographic response by RECIST criteria and all three individuals had a time to progression (TTP) >11.5 mo. A Cox regression analysis followed by likelihood-ratio test revealed a positive correlation (p=0.0198) between DC derived IL-12p70 and TTP. Moreover, among clinical responders, vaccine-induced gp100-specific T cells displayed a Tc1 phenotype. In contrast, a selective defect in IL-12p35 transcription was identified in clinical non-responder patient DC and gp100-specific T cells from these patients displayed the Tc2 phenotype. Incorporation of TLR3 and TLR8 agonists into the CD40L/IFN-γ maturation protocol corrected the IL-12p70 production defect in DC derived from clinical non-responder patients. These findings underscore the essential role of IL-12p70 in the development of type-1 immunity in humans with cancer and provide evidence-based rationale for incorporating IL-12p70 into the next generation of cancer vaccine formulations. Citation Format: Beatriz M. Carreno, Michelle Becker-Hapak, Alexander Huang, Megan Chan, Amer Alyasiry, Wen-Rong Lie, Rebecca L. Aft, Lynn A. Cornelius, Katherine M. Trinkaus, Gerald P. Linette. IL-12p70 producing dendritic cell vaccine elicits Tc1 polarized T cells and extends time to progression in metastatic melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-157. doi:10.1158/1538-7445.AM2013-LB-157