Diagnostic and therapeutic potential of shark variable new antigen receptor (VNAR) single domain antibody.

Conventional monoclonal antibodies (mAbs) have been widely used in research and diagnostic applications due to their high affinity and specificity. However, multiple limitations, such as large size, complex structure and sensitivity to extreme ambient temperature potentially weaken the performance of mAbs in certain applications. To address this problem, the exploration of new antigen binders is extensively required in relation to improve the quality of current diagnostic platforms. In recent years, a new immunoglobulin-based protein, namely variable domain of new antigen receptor (VNAR) was discovered in sharks. Unlike conventional mAbs, several advantages of VNARs, include small size, better thermostability and peculiar paratope structure have attracted interest of researchers to further explore on it. This article aims to first present an overview of the shark VNARs and outline the characteristics as an outstanding new reagent for diagnostic and therapeutic applications.

The efficacy of chimeric antigen receptor (CAR) immunotherapy in animal models for solid tumors: A systematic review and meta-analysis.

BACKGROUND: Most recently, an emerging theme in the field of tumor immunology predominates: chimeric antigen receptor (CAR) therapy in treating solid tumors. The number of related preclinical trials was surging. However, an evaluation of the effects of preclinical studies remained absent. Hence, a meta-analysis was conducted on the efficacy of CAR in animal models for solid tumors. METHODS: The authors searched PubMed/Medline, Embase, and Google scholar up to April 2017. HR for survival was extracted based on the survival curve. The authors used fixed effect models to combine the results of all the trials. Heterogeneity was assessed by I-square statistic. Quality assessment was conducted following the Stroke Therapy Academic Industry Roundtable standard. Publication bias was assessed using Egger's test. RESULTS: Eleven trials were included, including 54 experiments with a total of 362 animals involved. CAR immunotherapy significantly improved the survival of animals (HR: 0.25, 95% CI: 0.13-0.37, P < 0.001). The quality assessment revealed that no study reported whether allocation concealment and blinded outcome assessment were conducted, and only five studies implemented randomization. CONCLUSIONS: This meta-analysis indicated that CAR therapy may be a potential clinical strategy in treating solid tumors.

Autologous T Cells Expressing CD30 Chimeric Antigen Receptors for Relapsed or Refractory Hodgkin Lymphoma: An Open-Label Phase I Trial.

Purpose: Relapsed or refractory Hodgkin lymphoma is a challenge for medical oncologists because of poor overall survival. We aimed to assess the feasibility, safety, and efficacy of CD30-targeting CAR T cells in patients with progressive relapsed or refractory Hodgkin lymphoma.Experimental Design: Patients with relapsed or refractory Hodgkin lymphoma received a conditioning chemotherapy followed by the CART-30 cell infusion. The level of CAR transgenes in peripheral blood and biopsied tumor tissues was measured periodically according to an assigned protocol by quantitative PCR (qPCR).Results: Eighteen patients were enrolled; most of whom had a heavy treatment history or multiple tumor lesions and received a mean of 1.56 × 107 CAR-positive T cell per kg (SD, 0.25; range, 1.1-2.1) in total during infusion. CART-30 cell infusion was tolerated, with grade ≥3 toxicities occurring only in two of 18 patients. Of 18 patients, seven achieved partial remission and six achieved stable disease. An inconsistent response of lymphoma was observed: lymph nodes presented a better response than extranodal lesions and the response of lung lesions seemed to be relatively poor. Lymphocyte recovery accompanied by an increase of circulating CAR T cells (peaking between 3 and 9 days after infusion) is a probable indictor of clinical response. Analysis of biopsied tissues by qPCR and immunohistochemistry revealed the trafficking of CAR T cells into the targeted sites and reduction of the expression of CD30 in tumors.Conclusions: CART-30 cell therapy was safe, feasible, and efficient in relapsed or refractory lymphoma and guarantees a large-scale patient recruitment. Clin Cancer Res; 23(5); 1156-66. ©2016 AACR.

The prospects and promise of chimeric antigen receptor immunotherapy in multiple myeloma.

Despite encouraging therapeutic advances, multiple myeloma (MM) remains an incurable malignancy. The exciting results of chimaeric antigen receptor (CAR)-based immunotherapy in CD19(+) B-cell malignancies have spurred a great interest in extending the use of the CAR technology to other cancers, including MM. Availability of a specific, tumour-restricted antigen is crucial for the design of successful antibody-based CAR therapy. However, in MM, as in other malignancies, the relative dearth of such antigens-targets represents the main obstacle for the wider pre-clinical development and clinical application of the CAR technology. Here we provide an overview of the current progress and future promises of CAR technology in MM therapy. We highlight that, owing to its complexity, phenotypic and functional heterogeneity and the impact of the microenvironment, MM poses several challenges for CAR-based therapeutic approaches. Nevertheless, for the same reasons, MM can serve as a paradigm for better understanding, optimization and overall improvement of the CAR technology for the benefit of cancer and myeloma patients.

Tuning Sensitivity of CAR to EGFR Density Limits Recognition of Normal Tissue While Maintaining Potent Antitumor Activity.

Many tumors overexpress tumor-associated antigens relative to normal tissue, such as EGFR. This limits targeting by human T cells modified to express chimeric antigen receptors (CAR) due to potential for deleterious recognition of normal cells. We sought to generate CAR(+) T cells capable of distinguishing malignant from normal cells based on the disparate density of EGFR expression by generating two CARs from monoclonal antibodies that differ in affinity. T cells with low-affinity nimotuzumab-CAR selectively targeted cells overexpressing EGFR, but exhibited diminished effector function as the density of EGFR decreased. In contrast, the activation of T cells bearing high-affinity cetuximab-CAR was not affected by the density of EGFR. In summary, we describe the generation of CARs able to tune T-cell activity to the level of EGFR expression in which a CAR with reduced affinity enabled T cells to distinguish malignant from nonmalignant cells.

The pharmacology of second-generation chimeric antigen receptors.

Second-generation chimeric antigen receptors (CARs) retarget and reprogramme T cells to augment their antitumour efficacy. The combined activating and co-stimulatory domains incorporated in these CARs critically determine the function, differentiation, metabolism and persistence of engineered T cells. CD19-targeted CARs that incorporate CD28 or 4-1BB signalling domains are the best known to date. Both have shown remarkable complete remission rates in patients with refractory B cell malignancies. Recent data indicate that CD28-based CARs direct a brisk proliferative response and boost effector functions, whereas 4-1BB-based CARs induce a more progressive T cell accumulation that may compensate for less immediate potency. These distinct kinetic features can be exploited to further develop CAR-based T cell therapies for a variety of cancers. A new field of immunopharmacology is emerging.

CCR 20th Anniversary Commentary: Chimeric Antigen Receptors-From Model T to the Tesla.

The research article by Kershaw and colleagues, published in the October 15, 2006, issue of Clinical Cancer Research, presents one of the first clinical trials to utilize chimeric antigen receptors. Subsequent studies have shown promise for the treatment of patients with lymphoid malignancies, but further progress will require optimization, including the identification of more specific antigens for solid tumors.

Chimeric antigen receptors against CD33/CD123 antigens efficiently target primary acute myeloid leukemia cells in vivo.

As significant numbers of acute myeloid leukemia (AML) patients are still refractory to conventional therapies or experience relapse, immunotherapy using T cells expressing chimeric antigen receptors (CARs) might represent a valid treatment option. AML cells frequently overexpress the myeloid antigens CD33 and CD123, for which specific CARs can be generated. However, CD33 is also expressed on normal hematopoietic stem/progenitor cells (HSPCs), and its targeting could potentially impair normal hematopoiesis. In contrast, CD123 is widely expressed by AML, while low expression is detected on HSPCs, making it a much more attractive target. In this study we describe the in vivo efficacy and safety of using cytokine-induced killer (CIK) cells genetically modified to express anti-CD33 or anti-CD123 CAR to target AML. We show that both these modified T cells are very efficient in reducing leukemia burden in vivo, but only the anti-CD123 CAR has limited killing on normal HSPCs, thus making it a very attractive immunotherapeutic tool for AML treatment.

Immunotherapy with chimeric antigen receptors for multiple myeloma.

Chimeric antigen receptors (CARs) are synthetic transmembrane proteins that are used to redirect autologous T cells with a new specificity for antigens on the surface of cancer cells. Impressive results from early phase clinical trials of anti-CD19 CARs for B cell malignancies have generated great enthusiasm for developing this approach for other diseases, particularly hematologic malignancies. Here we review efforts to develop CARs for the treatment of multiple myeloma. Clinical trials are underway investigating CARs against Kappa light chain, CD138, and Lewis Y antigen. CARs against BCMA, CS1, and CD38 are in pre-clinical testing. While initial clinical trials of novel CARs will focus on relapsed/refractory disease, CARs will also likely be studied as a consolidation strategy after response to first-line therapy or in conjunction with autologous hematopoietic stem cell transplantation.

New immune strategies for the treatment of acute lymphoblastic leukemia: antibodies and chimeric antigen receptors.

The prognosis of adult acute lymphoblastic leukemia (ALL) remains poor and novel treatment strategies are needed. Antibody-based therapies represent such an approach. ALL cells express various surface antigens that are targets for monoclonal antibodies. This review focuses on 4 major classes of antibody therapy: (1) naked antibodies, (2) T-cell-engaging bispecific single-chain antibodies, (3) immunoconjugates/immunotoxins, and (4) chimeric antigen receptors. Preclinical and clinical data are reviewed. This area of research represents an exciting new approach to help improve the outcome of this disease. Several clinical trials are currently incorporating this therapy in the treatment of newly diagnosed and relapsed adult ALL patients.

Chasing cancer with chimeric antigen receptor therapy.

Many attempts to use genetically modified T cells to halt tumor progression have been met with disappointment and significant challenges in the successful application within human patients. Porter et al., however, describe the use of genetically modified lymphocytes bearing a chimeric antigen receptor that bypasses many of the common limitations of adoptive lymphocyte therapy. Through incorporation of a costimulatory domain within the chimeric antigen receptor, the investigators engineered lymphocytes with significantly higher tumor rejection activity and demonstrated significant expansion and prolonged survival after in vivo transfer to a single patient who showed a complete regression of refractory chronic lymphoid leukemia. This recent success in using genetically modified T cells to kill chronic lymphoid leukemia tumor cells is an encouraging advancement in the development of specific and targeted immune-based therapies against cancer.

CAR T cells transform to trucks: chimeric antigen receptor-redirected T cells engineered to deliver inducible IL-12 modulate the tumour stroma to combat cancer.

Adoptive T cell therapy recently achieved impressive efficacy in early-phase clinical trials; this significantly raises the profile of immunotherapy in the fight against cancer. A broad variety of tumour cells can specifically be targeted by patients' T cells, which are redirected in an antibody-defined, major histocompatibility complex-unrestricted fashion by endowing them with a chimeric antigen receptor (CAR). Despite promising results for some haematologic malignancies, the stroma of large, established tumours, the broad plethora of infiltrating repressor cells, and cancer cell variants that had lost the target antigen limit their therapeutic efficacy in the long term. This article reviews a newly described strategy for overcoming some of these shortcomings by engineering CAR T cells with inducible or constitutive release of IL-12. Once redirected, these T cells are activated, and released IL-12 accumulates in the tumour lesion where it promotes tumour destruction by at least two mechanisms: (1) induction of an innate immune cell response towards those cancer cells which are invisible to redirected T cells and (2) triggering programmatic changes in immune-suppressive cells. Given the enormous complexity of both tumour progression and immune attack, the upcoming strategies using CAR-redirected T cells for local delivery of immune-modulating payloads exhibited remarkable efficacy in pre-clinical models, suggesting their evaluation in clinical trials.

Potential targets for pancreatic cancer immunotherapeutics.

Pancreatic adenocarcinoma is the fourth leading cause of cancer death with an overall 5-year survival of less than 5%. As there is ample evidence that pancreatic adenocarcinomas elicit antitumor immune responses, identification of pancreatic cancer-associated antigens has spurred the development of vaccination-based strategies for treatment. While promising results have been observed in animal tumor models, most clinical studies have found only limited success. As most trials were performed in patients with advanced pancreatic cancer, the contribution of immune suppressor mechanisms should be taken into account. In this article, we detail recent work in tumor antigen vaccination and the recently identified mechanisms of immune suppression in pancreatic cancer. We offer our perspective on how to increase the clinical efficacy of vaccines for pancreatic cancer.