Single versus combined immunoregulatory approach using PD-1 and CTLA-4 modulators in controlling sepsis

INTRODUCTION

Sepsis is a disease process characterized by an extreme inflammatory response followed by a period of severe immunosuppression. In recent years, there has been improved survival in the initial immune response during systemic inflammatory response syndrome, and compensatory anti-inflammatory response, yet is mostly unchanged with 18-30% mortality during the later stage of sepsis despite numerous Phase 3 clinical trials. Areas covered: This review article presents a critical evaluation of the most promising newer studies aimed at improving the immunosuppressive stage of sepsis. Administration of DHEA/AED/AET show promise in improving survival. Blockade of signaling pathways for PD-1/PD-L1/CTLA-4, and partial blockade of TREM-1 signaling, and modification to sTREM-1 and the JAK/STAT pathway are promising methods of restoring host immune response and improving survival. While there has been significant progress, currently no findings have been translated into effective clinical interventions. Expert commentary: Clinical success by immunomodulation with individual immune mediator is encouraging and should progress to evaluating combined methods of immunoregulation. Since most of the animal studies do not reproduce human sepsis, development of better animal models and moving toward human studies for intervention will lead to the most beneficial findings in translational science.

Tremelimumab (CP-675,206), a cytotoxic T lymphocyte associated antigen 4 blocking monoclonal antibody in clinical development for patients with cancer

Tremelimumab (CP-675,206) is a fully human monoclonal antibody specific for human cytotoxic T lymphocyte-associated antigen 4 (CTLA-4, CD152) in clinical development for patients with cancer. Blocking the CTLA-4 negative costimulatory receptor with the antagonistic antibody tremelimumab results in immune activation. Administration of tremelimumab to patients with locally advanced and metastatic melanoma has resulted in a subset of patients with durable objective tumor regressions. Its IgG(2) isotype minimizes the possibility of cytotoxic effects on activated T lymphocytes and cytokine release syndrome. Preclinical testing in vitro and in large animal models predicted the target concentrations of circulating antibody in humans necessary for a pharmacodynamic effect. Phase I clinical trials provided evidence of dose- or exposure-related effects consistent with the anticipated mechanism of action. Further clinical development has led to two ongoing registration trials in patients with metastatic melanoma: a phase III randomized trial of tremelimumab versus dacarbazine or temozolomide in previously untreated patients with advanced melanoma and a phase II trial of tremelimumab in previously treated patients with advanced melanoma.