Monoclonal antibodies to chemokine receptors

Chemokine receptor-specific antibodies in cancer immunotherapy: achievements and challenges

The 1990s brought a burst of information regarding the structure, expression pattern, and role in leukocyte migration and adhesion of chemokines and their receptors. At that time, the FDA approved the first therapeutic antibodies for cancer treatment. A few years later, it was reported that the chemokine receptors CXCR4 and CCR7 were involved on directing metastases to liver, lung, bone marrow, or lymph nodes, and the over-expression of CCR4, CCR6, and CCR9 by certain tumors. The possibility of inhibiting the interaction of chemokine receptors present on the surface of tumor cells with their ligands emerged as a new therapeutic approach. Therefore, many research groups and companies began to develop small molecule antagonists and specific antibodies, aiming to neutralize signaling from these receptors. Despite great expectations, so far, only one anti-chemokine receptor antibody has been approved for its clinical use, mogamulizumab, an anti-CCR4 antibody, granted in Japan to treat refractory adult T-cell leukemia and lymphoma. Here, we review the main achievements obtained with anti-chemokine receptor antibodies for cancer immunotherapy, including discovery and clinical studies, proposed mechanisms of action, and therapeutic applications.

TIM-3 is expressed on activated human CD4+ T cells and regulates Th1 and Th17 cytokines

TIM-3 is a molecule selectively expressed on a subset of murine IFN-gamma-secreting T helper 1 (Th1) cells but not Th2 cells, and regulates Th1 immunity and tolerance in vivo. At this time little is known about the role of TIM-3 on human T cells. To determine if TIM-3 similarly identifies and regulates Th1 cells in humans, we generated a panel of mAb specific for human TIM-3. We report that TIM-3 is expressed by a subset of activated CD4(+) cells, and that anti-CD3/anti-CD28 stimulation increases both the level of expression as well as the number of TIM-3(+) T cells. We also find that TIM-3 is expressed at high levels on in vitro polarized Th1 cells, and is expressed at lower levels on Th17 cells. In addition, human CD4(+) T cells secreted elevated levels of IFN-gamma, IL-17, IL-2, and IL-6, but not IL-10, IL-4, or TNF-alpha, when stimulated with anti-CD3/anti-CD28 in the presence of TIM-3-specific, putative antagonistic antibodies. This was not mediated by differences in proliferation or cell death, but rather by induction of cytokines at the transcriptional level. These results suggest that TIM-3 is a negative regulator of human T cells and regulates Th1 and Th17 cytokine secretion.

Antibodies produced by clonally expanded plasma cells in multiple sclerosis cerebrospinal fluid

OBJECTIVE

Intrathecal IgG synthesis, persistence of bands of oligoclonal IgG, and memory B-cell clonal expansion are well-characterized features of the humoral response in multiple sclerosis (MS). Nevertheless, the target antigen of this response remains enigmatic.

METHODS

We produced 53 different human IgG1 monoclonal recombinant antibodies (rAbs) by coexpressing paired heavy- and light-chain variable region sequences of 51 plasma cell clones and 2 B-lymphocyte clones from MS cerebrospinal fluid in human tissue culture cells. Chimeric control rAbs were generated from anti-myelin hybridomas in which murine variable region sequences were fused to human constant region sequences. Purified rAbs were exhaustively assayed for reactivity against myelin basic protein, proteolipid protein, and myelin oligodendrocyte glycoprotein by immunostaining of transfected cells expressing individual myelin proteins, by protein immunoblotting, and by immunostaining of human brain tissue sections.

RESULTS

Whereas humanized control rAbs derived from anti-myelin hybridomas and anti-myelin monoclonal antibodies readily detected myelin antigens in multiple immunoassays, none of the rAbs derived from MS cerebrospinal fluid displayed immunoreactivity to the three myelin antigens tested. Immunocytochemical analysis of tissue sections from MS and control brain demonstrated only weak staining with a few rAbs against nuclei or cytoplasmic granules in neurons, glia, and inflammatory cells.

INTERPRETATION

The oligoclonal B-cell response in MS cerebrospinal fluid is not targeted to the well-characterized myelin antigens myelin basic protein, proteolipid protein, or myelin oligodendrocyte glycoprotein.