Endogenous antibodies for tumor detection

Fighting rare cancers: lessons from fibrolamellar hepatocellular carcinoma

The fight against rare cancers faces myriad challenges, including missed or wrong diagnoses, lack of information and diagnostic tools, too few samples and too little funding. Yet many advances in cancer biology, such as the realization that there are tumour suppressor genes, have come from studying well-defined, albeit rare, cancers. Fibrolamellar hepatocellular carcinoma (FLC), a typically lethal liver cancer, mainly affects adolescents and young adults. FLC is both rare, 1 in 5 million, and problematic to diagnose. From the paucity of data, it was not known whether FLC was one cancer or a collection with similar phenotypes, or whether it was genetically inherited or the result of a somatic mutation. A personal journey through a decade of work reveals answers to these questions and a road map of steps and missteps in our fight against a rare cancer.

Rapid, site-specific labeling of "off-the-shelf" and native serum autoantibodies with T cell-redirecting domains

Extensive antibody engineering and cloning is typically required to generate new bispecific antibodies. Made-to-order genes, advanced expression systems, and high-efficiency cloning can simplify and accelerate this process, but it still can take months before a functional product is realized. We developed a simple method to site-specifically and covalently attach a T cell-redirecting domain to any off-the-shelf, human immunoglobulin G (IgG) or native IgG isolated from serum. No antibody engineering, cloning, or knowledge of the antibody sequence is required. Bispecific antibodies are generated in just hours. By labeling antibodies isolated from tumor-bearing mice, including two syngeneic models, we generated T cell-redirecting autoantibodies (TRAAbs) that act as an effective therapeutic. TRAAbs preferentially bind tumor tissue over healthy tissue, indicating a previously unexplored therapeutic window. The use of autoantibodies to direct the tumor targeting of bispecific antibodies represents a new paradigm in personalized medicine that eliminates the need to identify tumor biomarkers.

Pushing Past the Blockade: Advancements in T Cell-Based Cancer Immunotherapies

Successful cancer immunotherapies rely on a replete and functional immune compartment. Within the immune compartment, T cells are often the effector arm of immune-based strategies due to their potent cytotoxic capabilities. However, many tumors have evolved a variety of mechanisms to evade T cell-mediated killing. Thus, while many T cell-based immunotherapies, such as immune checkpoint inhibition (ICI) and chimeric antigen receptor (CAR) T cells, have achieved considerable success in some solid cancers and hematological malignancies, these therapies often fail in solid tumors due to tumor-imposed T cell dysfunctions. These dysfunctional mechanisms broadly include reduced T cell access into and identification of tumors, as well as an overall immunosuppressive tumor microenvironment that elicits T cell exhaustion. Therefore, novel, rational approaches are necessary to overcome the barriers to T cell function elicited by solid tumors. In this review, we will provide an overview of conventional immunotherapeutic strategies and the various barriers to T cell anti-tumor function encountered in solid tumors that lead to resistance. We will also explore a sampling of emerging strategies specifically aimed to bypass these tumor-imposed boundaries to T cell-based immunotherapies.

Humanization of Immunodeficient Animals for the Modeling of Transplantation, Graft Versus Host Disease, and Regenerative Medicine

The humanization of animals is a powerful tool for the exploration of human disease pathogenesis in biomedical research, as well as for the development of therapeutic interventions with enhanced translational potential. Humanized models enable us to overcome biologic differences that exist between humans and other species, while giving us a platform to study human processes in vivo. To become humanized, an immune-deficient recipient is engrafted with cells, tissues, or organoids. The mouse is the most well studied of these hosts, with a variety of immunodeficient strains available for various specific uses. More recently, efforts have turned to the humanization of other animal species such as the rat, which offers some technical and immunologic advantages over mice. These advances, together with ongoing developments in the incorporation of human transgenes and additional mutations in humanized mouse models, have expanded our opportunities to replicate aspects of human allotransplantation and to assist in the development of immunotherapies. In this review, the immune and tissue humanization of various species is presented with an emphasis on their potential for use as models for allotransplantation, graft versus host disease, and regenerative medicine.

Natural Killer Cells: Tumor Surveillance and Signaling

Natural killer (NK) cells play a pivotal role in cancer immunotherapy due to their innate ability to detect and kill tumorigenic cells. The decision to kill is determined by the expression of a myriad of activating and inhibitory receptors on the NK cell surface. Cell-to-cell engagement results in either self-tolerance or a cytotoxic response, governed by a fine balance between the signaling cascades downstream of the activating and inhibitory receptors. To evade a cytotoxic immune response, tumor cells can modulate the surface expression of receptor ligands and additionally, alter the conditions in the tumor microenvironment (TME), tilting the scales toward a suppressed cytotoxic NK response. To fully harness the killing power of NK cells for clinical benefit, we need to understand what defines the threshold for activation and what is required to break tolerance. This review will focus on the intracellular signaling pathways activated or suppressed in NK cells and the roles signaling intermediates play during an NK cytotoxic response.

Cancer Self-Defense: An Immune Stealth

The hurdles in realizing successful cancer immunotherapy stem from the fact that cancer patients are either refractory to immune response and/or develop resistance. Here, we propose that these phenomena are due, in part, to the deployment/secretion of a "decoy flare," for example, anomalous cancer-associated antigens by the tumor cells. The cancer secretome, which resembles the parent cell make-up, is composed of soluble macromolecules (proteins, glycans, lipids, DNAs, RNAs, etc.) and insoluble vesicles (exosomes), thus hindering cancer detection/recognition by immunotherapeutic agents, resulting in a "cancer-stealth" effect. Immunotherapy, or any treatment that relies on antigens' expression/function, could be improved by the understanding of the properties of the cancer secretome, as its clinical evaluation may change the therapeutic landscape. Cancer Res; 77(20); 5441-4. ©2017 AACR.