Differential expression of CCR8 in tumors versus normal tissue allows specific depletion of tumor-infiltrating T regulatory cells by GS-1811, a novel Fc-optimized anti-CCR8 antibody.

The presence of T regulatory (Treg) cells in the tumor microenvironment is associated with poor prognosis and resistance to therapies aimed at reactivating anti-tumor immune responses. Therefore, depletion of tumor-infiltrating Tregs is a potential approach to overcome resistance to immunotherapy. However, identifying Treg-specific targets to drive such selective depletion is challenging. CCR8 has recently emerged as one of these potential targets. Here, we describe GS-1811, a novel therapeutic monoclonal antibody that specifically binds to human CCR8 and is designed to selectively deplete tumor-infiltrating Tregs. We validate previous findings showing restricted expression of CCR8 on tumor Tregs, and precisely quantify CCR8 receptor densities on tumor and normal tissue T cell subsets, demonstrating a window for selective depletion of Tregs in the tumor. Importantly, we show that GS-1811 depleting activity is limited to cells expressing CCR8 at levels comparable to tumor-infiltrating Tregs. Targeting CCR8 in mouse tumor models results in robust anti-tumor efficacy, which is dependent on Treg depleting activity, and synergizes with PD-1 inhibition to promote anti-tumor responses in PD-1 resistant models. Our data support clinical development of GS-1811 to target CCR8 in cancer and drive tumor Treg depletion in order to promote anti-tumor immunity.

Cell engineering with microfluidic squeezing preserves functionality of primary immune cells in vivo.

The translational potential of cell-based therapies is often limited by complications related to effectively engineering and manufacturing functional cells. While the use of electroporation is widespread, the impact of electroporation on cell state and function has yet to be fully characterized. Here, we use a genome-wide approach to study optimized electroporation treatment and identify striking disruptions in the expression profiles of key functional transcripts of human T cells. These genetic disruptions result in concomitant perturbation of cytokine secretion including a 648-fold increase in IL-2 secretion (P < 0.01) and a 30-fold increase in IFN-γ secretion (P < 0.05). Ultimately, the effects at the transcript and protein level resulted in functional deficiencies in vivo, with electroporated T cells failing to demonstrate sustained antigen-specific effector responses when subjected to immunological challenge. In contrast, cells subjected to a mechanical membrane disruption-based delivery mechanism, cell squeezing, had minimal aberrant transcriptional responses [0% of filtered genes misregulated, false discovery rate (FDR) q < 0.1] relative to electroporation (17% of genes misregulated, FDR q < 0.1) and showed undiminished effector responses, homing capabilities, and therapeutic potential in vivo. In a direct comparison of functionality, T cells edited for PD-1 via electroporation failed to distinguish from untreated controls in a therapeutic tumor model, while T cells edited with similar efficiency via cell squeezing demonstrated the expected tumor-killing advantage. This work demonstrates that the delivery mechanism used to insert biomolecules affects functionality and warrants further study.