Immunology and Biotherapies

Abstract

Enhancing immune responses with immune-modulatory monoclonal antibodies directed to inhibitory immune receptors is a promising modality in cancer therapy. Clinical efficacy has been demonstrated with antibodies blocking inhibitory immune checkpoints such as cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) or PD-1/PD-L1. Treatment with ipilimumab, a fully human CTLA-4–specific mAb, showed durable clinical efficacy in metastatic melanoma; its mechanism of action is, however, only partially understood. This is a study of 29 patients with advanced cutaneous melanoma treated with ipilimumab. We analyzed peripheral blood mononuclear cells (PBMCs) and matched melanoma metastases from 15 patients responding and 14 not responding to ipilimumab by multicolor flow cytometry, antibody-dependent cell-mediated cytotoxicity (ADCC) assay, and immunohistochemistry. PBMCs and matched tumor biopsies were collected 24 h before (i.e., baseline) and up to 4 wk after ipilimumab. Our findings show, to our knowledge for the first time, that ipilimumab can engage ex vivo FcγRIIIA (CD16)-expressing, nonclassical monocytes resulting in ADCC-mediated lysis of regulatory T cells (Tregs). In contrast, classical CD14++CD16−monocytes are unable to do so. Moreover, we show that patients responding to ipilimumab display significantly higher baseline peripheral frequencies of nonclassical monocytes compared with nonresponder patients. In the tumor microenvironment, responders have higher CD68+/CD163+ macrophage ratios at baseline and show decreased Treg infiltration after treatment. Together, our results suggest that anti–CTLA-4 therapy may target Tregs in vivo. Larger translational studies are, however, warranted to substantiate this mechanism of action of ipilimumab in patients.

Via Krishan Maggon

TIL Technology 

In the early stages of cancer, special immune cells known as tumor infiltrating lymphocytes (TILs) migrate to the tumor and launch an attack.  However, this effect is usually short-lived because cancer adapts to evade immune detection and suppress immune response. Lion’s TIL technology is designed to overcome the immunosuppressive effects of cancer, while leveraging and enhancing the power of TILs to treat, and potentially cure, all solid tumors.

Our TIL technology has demonstrated robust efficacy in Phase 2 clinical trials, indicating objective response rates of 49% in Stage 4 metastatic melanoma.  Based on an adoptive cell therapy regimen developed by Steven A. Rosenberg, MD, chief of surgery at National Cancer Institute (NCI), it is currently in use as a physician-sponsored investigational treatment for Stage IV metastatic melanoma at NCI, MD Anderson Cancer Center, and the H. Lee Moffitt Cancer & Research Institute.

Via Krishan Maggon