Engineering T cell response to cancer antigens by choice of focal therapeutic conditions

Abstract

Focal thermal therapy (Heat), cryosurgery (Cryo) and irreversible electroporation (IRE) are increasingly used to treat cancer. However, local recurrence and systemic spread are persistent negative outcomes. Nevertheless, emerging work with immunotherapies (i.e., checkpoint blockade or dendritic cell (DC) vaccination) in concert with focal therapies may improve outcomes. To understand the role of focal therapy in priming the immune system for immunotherapy, an in vitro model of T cell response after exposure to B16 melanoma cell lysates after lethal exposures was designed. Exposure included: Heat (50 C, 30 min), Cryo (À80 C, 30 min) and IRE (1250 V/cm, 99 pulses, 50 ms pulses with 1 Hz intervals). After viability assessment (CCK-8 assay), cell lysates were collected and assessed for protein release (BCA assay), protein denaturation (FTIR-spectroscopy), TRP-2 antigen release (western blot), and T cell activation (antigen-specific CD8 T cell proliferation). Results showed IRE released the most protein and antigen (TRP-2), followed by Cryo and Heat. In contrast, Cryo released the most native (not denatured) protein, compared to IRE and Heat. Finally, IRE dramatically outperformed both Cryo and Heat in T cell activation while Cryo modestly outperformed Heat. This study demonstrates that despite all focal therapies ability to destroy cells, the 'quantity' (i.e., amount) and 'quality' (i.e., molecular state) of tumor protein (including antigen) released can dramatically change the ensuing priming of the immune system. This suggests protein-based metrics whereby focal therapies can be designed to prime the immune system in concert with immunotherapies to eventually achieve improved and durable cancer treatment in vivo.

Irreversible Electroporation: Background, Theory, and Review of Recent Developments in Clinical Oncology

“…131 Furthermore, recent in vitro work has shown that melanoma cells ablated with IRE release substantially more protein and TRP-2 antigen than those treated with thermal ablation (heating and cryoablation). 132 Additional analyses showed that protein released from IRE-treated cells was more efficient at inducing T cell proliferation than that released from heat-or cryotherapytreated cells, supporting the observation that IRE reduces the rate of metastases in a rabbit VX2 model 133 and exhibits a stronger abscopal effect than thermal ablation. 134 Improved immune response versus other modalities could be due to release of intracellular contents or direct modulation of cell signaling, but further investigation is warranted.…”

Temporal Characterization of Blood–Brain Barrier Disruption with High-Frequency Electroporation

“…Combinatorial therapy, including the selective use of HFE-mediated BBBD, would constitute a highly selective yet grossly effective therapy for brain tumor elimination. As evidenced in recent studies demonstrating a robust adaptive and innate immune response to tumors following electroporation-based therapies [57,58]; HFE now may evolve as a potential therapy not only targeting early stage tumors, but also late-stage and metastasized cancers.…”

Starting a Fire Without Flame: The Induction of Cell Death and Inflammation in Electroporation-Based Tumor Ablation Strategies

“…Unfortunately, tumor location near critical structures can lead to hemorrhaging, heat sink effects, and healthy tissue damages during treatment (5,6). Nonthermal modalities such as those that utilize electroporation can overcome these treatment barriers to induce cell death through different mechanisms and may initiate systemic immune responses to target both the local tumor microenvironment and metastatic sites (7)(8)(9)(10).…”