Jaina Patel

Allogeneic tumor cell vaccines: The promise and limitations in clinical trials

The high mortality rate associated with cancer and its resistance to conventional treatments such as radiation and chemotherapy has led to the investigation of a variety of anti-cancer immunotherapies. The development of novel immunotherapies has been bolstered by the discovery of tumor-associated antigens (TAAs), through gene sequencing and proteomics. One such immunotherapy employs established allogeneic human cancer cell lines to induce antitumor immunity in patients through TAA presentation. Allogeneic cancer immunotherapies are desirable in a clinical setting due to their ease of production and availability. This review aims to summarize clinical trials of allogeneic tumor immunotherapies in various cancer types. To date, clinical trials have shown limited success due potentially to extensive degrees of inter- and intra-tumoral heterogeneity found among cancer patients. However, these clinical results provide guidance for the rational design and creation of more effective allogeneic tumor immunotherapies for use as monotherapies or in combination with other therapies.

Taming dendritic cells with TIM-3: another immunosuppressive strategy used by tumors

Evaluation of: Chiba S, Baghdadi M, Akiba H et al. Tumor-infiltrating DCs suppress nucleic acid-mediated innate immune responses through interactions between the receptor TIM-3 and the alarmin HMGB1. Nat. Immunol. 13, 832-842 (2012). The identification of TIM-3 expression on tumor-associated dendritic cells (TADCs) provides insight into another aspect of tumor-mediated immunosuppression. The role of TIM-3 has been well characterized on tumor-infiltrating T cells; however, its role on TADCs was not previously known. The current paper demonstrated that TIM-3 was predominantly expressed by TADCs and its interaction with the nuclear protein HMGB1 suppressed nucleic acid-mediated activation of an effective antitumor immune response. The authors were able to show that TIM-3 interaction with HMGB1 prevented the localization of nucleic acids into endosomal vesicles. Furthermore, chemotherapy was found to be more effective in anti-TIM-3 monoclonal antibody-treated mice or mice depleted of all DCs, which indicated that a significant role is played by TADCs in inhibiting tumor regression. Taken together, these findings identify TIM-3 as a potential target for inducing antitumor immunity in conjunction with DNA vaccines and/or immunogenic chemotherapy in clinical settings.

Immunotherapeutic strategies for cancer treatment: a novel protein transfer approach for cancer vaccine development.

Cancer cells have developed numerous ways to escape immune surveillance and gain unlimited proliferative capacity. Currently, several chemotherapeutic agents and radiotherapy, either alone or in combination, are being used to treat malignancies. However, both of these therapies are associated with several limitations and detrimental side effects. Therefore, recent scientific investigations suggest that immunotherapy is among the most promising new approaches in modern cancer therapy. The focus of cancer immunotherapy is to boost both acquired and innate immunity against malignancies by specifically targeting tumor cells, and leaving healthy cells and tissues unharmed. Cellular, cytokine, gene, and monoclonal antibody therapies have progressively become promising immunotherapeutic approaches that are being tested for several cancers in preclinical models as well as in the clinic. In this review, we discuss recent advances in these immunotherapeutic approaches, focusing on new strategies that allow the expression of specific immunostimulatory molecules on the surface of tumor cells to induce robust antitumor immunity.

Influenza virus-like particles engineered by protein transfer with tumor-associated antigens induces protective antitumor immunity.

Delivery of antigen in particulate form using either synthetic or natural particles induces stronger immunity than soluble forms of the antigen. Among naturally occurring particles, virus‐like particles (VLPs) have been genetically engineered to express tumor‐associated antigens (TAAs) and have shown to induce strong TAA‐specific immune responses due to their nano‐particulate size and ability to bind and activate antigen‐presenting cells. In this report, we demonstrate that influenza VLPs can be modified by a protein transfer technology to express TAAs for induction of effective antitumor immune responses. We converted the breast cancer HER‐2 antigen to a glycosylphosphatidylinositol (GPI)‐anchored form and incorporated GPI‐HER‐2 onto VLPs by a rapid protein transfer process. Expression levels on VLPs depended on the GPI‐HER‐2 concentration added during protein transfer. Vaccination of mice with protein transferred GPI‐HER‐2‐VLPs induced a strong Th1 and Th2‐type anti‐HER‐2 antibody response and protected mice against a HER‐2‐expressing tumor challenge. The Soluble form of GPI‐HER‐2 induced only a weak Th2 response under similar conditions. These results suggest that influenza VLPs can be enriched with TAAs by protein transfer to develop effective VLP‐based subunit vaccines against cancer without chemical or genetic modifications and thus preserve the immune stimulating properties of VLPs for easier production of antigen‐specific therapeutic cancer vaccines. Biotechnol. Bioeng. 2015;112: 1102–1110.

Hydrodynamic delivery of plasmid DNA encoding human FcγR-Ig dimers blocks immune-complex mediated inflammation in mice.

Therapeutic use and function of recombinant molecules can be studied by the expression of foreign genes in mice. In this study, we have expressed human Fcγ receptor–Ig fusion molecules (FcγR-Igs) in mice by administering FcγR-Ig plasmid DNAs hydrodynamically and compared their effectiveness with purified molecules in blocking immune-complex (IC)-mediated inflammation in mice. The concentration of hydrodynamically expressed FcγR-Igs (CD16AF-Ig, CD32AR-Ig and CD32AH-Ig) reached a maximum of 130 μg ml–1 of blood within 24 h after plasmid DNA administration. The in vivo half-life of FcγR-Igs was found to be 9–16 days and western blot analysis showed that the FcγR-Igs were expressed as a homodimer. The hydrodynamically expressed FcγR-Igs blocked 50–80% of IC-mediated inflammation up to 3 days in a reverse passive Arthus reaction model. Comparative analysis with purified molecules showed that hydrodynamically expressed FcγR-Igs are more efficient than purified molecules in blocking IC-mediated inflammation and had a higher half-life. In summary, these results suggest that the administration of a plasmid vector with the FcγR-Ig gene can be used to study the consequences of blocking IC binding to FcγRs during the development of inflammatory diseases. This approach may have potential therapeutic value in treating IC-mediated inflammatory autoimmune diseases such as lupus, arthritis and autoimmune vasculitis.

Protein transfer-mediated surface engineering to adjuvantate virus-like nanoparticles for enhanced anti-viral immune responses

UNLABELLED Recombinant virus-like nanoparticles (VLPs) are a promising nanoparticle platform to develop safe vaccines for many viruses. Herein, we describe a novel and rapid protein transfer process to enhance the potency of enveloped VLPs by decorating influenza VLPs with exogenously added glycosylphosphatidylinositol-anchored immunostimulatory molecules (GPI-ISMs). With protein transfer, the level of GPI-ISM incorporation onto VLPs is controllable by varying incubation time and concentration of GPI-ISMs added. ISM incorporation was dependent upon the presence of a GPI-anchor and incorporated proteins were stable and functional for at least 4weeks when stored at 4°C. Vaccinating mice with GPI-granulocyte macrophage colony-stimulating factor (GM-CSF)-incorporated-VLPs induced stronger antibody responses and better protection against a heterologous influenza virus challenge than unmodified VLPs. Thus, VLPs can be enriched with ISMs by protein transfer to increase the potency and breadth of the immune response, which has implications in developing effective nanoparticle-based vaccines against a broad spectrum of enveloped viruses. FROM THE CLINICAL EDITOR The inherent problem with current influenza vaccines is that they do not generate effective cross-protection against heterologous viral strains. In this article, the authors described the development of virus-like nanoparticles (VLPs) as influenza vaccines with enhanced efficacy for cross-protection, due to an easy protein transfer modification process.

Cancer CARtography: charting out a new approach to cancer immunotherapy

Evaluation of: Davila ML, Riviere I, Wang X et al. Efficacy and toxicity management of 19-28z CAR T cell therapy in B cell acute lymphoblastic leukemia. Sci. Transl. Med. 6(224), 224ra25 (2014). Recently, chimeric antigen receptor (CAR) T-cell immunotherapy has entered clinical trials in patients with relapsed or refractory B-cell acute lymphoblastic leukemia. 19-28z CAR T cells express a fusion protein comprised of an anti-CD19 mAb fused with CD28 costimulatory and CD3-zeta-chain signaling domains. The current paper demonstrates that administration of 19-28z CAR T cells in patients with relapsed or refractory B-ALL in a Phase I clinical trial has led to 88% of patients undergoing complete remission. Despite the benefits, CAR T-cell therapy is associated with cytokine release syndrome toxicities. The authors demonstrated criteria to diagnose severe cytokine release syndrome (sCRS) and treated sCRS with either high-dose steroids or with tocilizumab, an IL-6 receptor-specific mAb. Although both alleviated sCRS, steroid treatment negated the beneficial effects of CAR T-cell therapy, whereas tocilizumab did not. Taken together, CAR T-cell immunotherapy can be used as a safe and effective approach against tumors with known tumor-associated antigens.

Expression of membrane anchored cytokines and B7-1 alters tumor microenvironment and induces protective antitumor immunity in a murine breast cancer model

Many studies have shown that the systemic administration of cytokines or vaccination with cytokine-secreting tumors augments an antitumor immune response that can result in eradication of tumors. However, these approaches are hampered by the risk of systemic toxicity induced by soluble cytokines. In this study, we have evaluated the efficacy of 4TO7, a highly tumorigenic murine mammary tumor cell line, expressing glycosyl phosphatidylinositol (GPI)-anchored form of cytokine molecules alone or in combination with the costimulatory molecule B7-1 as a model for potential cell or membrane-based breast cancer vaccines. We observed that the GPI-anchored cytokines expressed on the surface of tumor cells greatly reduced the overall tumorigenicity of the 4TO7 tumor cells following direct live cell challenge as evidenced by transient tumor growth and complete regression within 30 days post challenge. Tumors co-expressing B7-1 and GPI-IL-12 grew the least and for the shortest duration, suggesting that this combination of immunostimulatory molecules is most potent. Protective immune responses were also observed following secondary tumor challenge. Further, the 4TO7-B7-1/GPI-IL-2 and 4TO7-B7-1/GPI-IL-12 transfectants were capable of inducing regression of a wild-type tumor growing at a distant site in a concomitant tumor challenge model, suggesting the tumor immunity elicited by the transfectants can act systemically and inhibit the tumor growth at a distant site. Additionally, when used as irradiated whole cell vaccines, 4TO7-B7-1/GPI-IL-12 led to a significant inhibition in tumor growth of day 7 established tumors. Lastly, we observed a significant decrease in the prevalence of myeloid-derived suppressor cells and regulatory T-cells in the tumor microenvironment on day 7 post challenge with 4TO7-B7-1/GPI-IL-12 cells, which provides mechanistic insight into antitumor efficacy of the tumor-cell membrane expressed IL-12. These studies have implications in designing membrane-based therapeutic vaccines with GPI-anchored cytokines for breast cancer.

Lipid-Mediated Cell Surface Engineering

Cell membranes provide not only a physical barrier between the extracellular and intracellular space, but they also contain many proteins, which serve as mediators of inside-out and outside-in signals essential for cell survival and functions. Therefore, these cell surfaces can be engineered to manipulate cellular functions. Lipid-mediated protein transfer allows for decoration of the cell surface by exogenous incorporation of proteins that are modified with hydrophobic tails into lipid bilayers. Protein transfer allows for controllable expression of functional protein on the periphery of cells in an easy, time-efficient manner, and can be performed in either a direct one-step incorporation method or an indirect two-step incorporation method. This technology has led to breakthroughs in designing tumor vaccines, targeted-drug delivery, enhancing function of killer immune cells, and engineering antigen-presenting cells.

Effects of Anchor Structure and Glycosylation of Fcγ Receptor III on Ligand Binding Affinity

The anchor structure of CD16 affects its binding affinity in a ligand-specific manner. The ligand binding affinity decreases for human IgG1 but increases for murine IgG2a when the anchor is changed from full to partial to none. Removing N-glycosylation from CD16 also increases the ligand binding affinity.