Abstract 2653: Tremelimimab plus tumor ablation for patients with hepatocellular carcinoma: Clinical results, immunomonitoring analysis of peripheral T cells and tumor biopsies

Abstract

Abstract Introduction: Ipilimumab, an anti-CTLA4 mAb, is the first immune-checkpoint inhibitor, to be approved by the FDA for the treatment of patients with melanoma. We performed a phase I/II clinical trial in patients with advanced hepatocellular carcinoma, who progressed on standard of care. Patients were treated with tremelimumab, another anti-CTLA4 mAb, and tumor ablation (radiofrequency ablation, cryoablation, and transcatheter arterial chemoembolization) to augment anti-tumor immunity. Peripheral blood mononuclear cells, viral load (HBV/HCV) and tumor biopsies were studied and clinical efficacy was correlated with immune monitoring results. Methods: Patients with HCC were enrolled in a study of tremelimumab combined with tumor ablation performed on week 6. Tumor biopsies were performed at baseline and at time of RFA/TACE and analyzed by immunohistochemistry. Gene expression analysis was performed using Nanostring technology and QIAGEN's Ingenuity Pathway Analysis (IPA) software. Eleven-color flow cytometry was performed to study peripheral blood mononuclear cells obtained at baseline, after 4 and 8 weeks using the following antibodies: CD4, CD3, CD4, CD8, CD11c, CD14, CD19, CD20, CD25, CD38, CD45RA, CD56, CD123, CD127, CCR7, CCR4, CXCR3, PD-1, 4-1BB, TIM3, CTLA4, PD-L1, ICOS, HLA-DR, AFP- and survivin-HLA-A2 tetramer. HCV and HBV viral load was determined in serum samples. Results: 27 patients were enrolled. 12 patients received TACE and 13 underwent tumor ablation during week 6 of tremelimumab therapy. Of N = 10 patients evaluable for response outside of TACE/RFA-treated lesion, 4 (40%) achieved confirmed partial responses. 6-week tumor biopsies showed clear increase in the number of CD3+ and CD8+ T cells in patients showing a clinical response only. Multi-color flow cytometry of PBMC revealed statistically significant changes after the 1st cycle in activated CD4+ and CD8+ T cells. The CD4/Treg and CD8/Treg ratio increased only in patients showing a clinical response. Both AFP and survivin specific CD8+ T cells were detected in HLA-A2+ patients, but there was no change in the frequency of these cells upon treatment. However PD1 expression increased over time both on AFP and survivin specific T cells. Finally, eight of 9 patients with quantifiable HCV experienced a marked reduction in viral load. 100% (N = 4) of HBV patients experienced a reduction in quantitative HBsAg. Pathway analysis conducted through IPA revealed that the top canonical pathways upregulated by treatment were T-cell receptor, Ephrin-A, IL-1, G-coupled protein, and IL-6 signaling. Conclusions: Tremelimumab in combination with subtotal TACE or RFA leads to an accumulation of intratumoral CD8+ T cells, activation of CD4+ and CD8+ T cells in peripheral blood and reduction in HCV viral load and HBsAg in patients showing clinical response to therapy. Citation Format: Ashish Uppala, Mei ElGindi, Firouzeh Korangy, Drew Pratt, David Venzon, Austin Duffy, Oxana Rusher, David Kleiner, Elliot Levy, Bradford Wood, Tim Greten. Tremelimimab plus tumor ablation for patients with hepatocellular carcinoma: Clinical results, immunomonitoring analysis of peripheral T cells and tumor biopsies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2653.