Homogeneous antibody and CAR-T cells with improved effector functions targeting SSEA-4 glycan on pancreatic cancer

Antibody-drug conjugates targeting SSEA-4 inhibits growth and migration of SSEA-4 positive breast cancer cells

Although breast cancer treatment has evolved significantly in recent years, drug resistance remains a major challenge. To identify new targets for breast cancer, we found that stage-specific embryonic antigen 4 (SSEA-4) is expressed in all subtypes of breast cancer cell lines, and the increased expression of the associated enzymes β3GalT5 and ST3Gal2 correlates with poor recurrence-free survival (RFS) in breast cancer. We also found that SSEA-4 antibodies can be rapidly internalized into breast cancer cells, a property that makes SSEA-4 an attractive target for antibody-drug conjugates (ADCs). Furthermore, the SSEA-4 antibody conjugated to the anticancer agents showed efficacy against SSEA-4-positive breast cancer cells, including those resistant to PARP inhibitor, trastuzumab, and CDK7 inhibitor. In addition, SSEA-4 ADCs showed no efficacy in β3GalT5-knockout MDA-MB-231 cells, highlighting the essential role of SSEA-4 as the target antigen for ADCs activity. Our work shows that SSEA-4-ADCs could be a therapeutic option for breast cancers.

Screening the human miRNA interactome reveals coordinated up-regulation in melanoma, adding bidirectional regulation to miRNA networks

Cellular protein expression is coordinated posttranscriptionally by an intricate regulatory network. The current presumption is that microRNAs (miRNAs) work by repression of functionally related targets within a system. In recent work, up-regulation of protein expression via direct interactions of messenger RNA with miRNA has been found in dividing cells, providing an additional mechanism of regulation. Herein, we demonstrate coordinated up-regulation of functionally coupled proteins by miRNA. We focused on CD98hc, the heavy chain of the amino acid transporter LAT-1, and α-2,3-sialyltransferases ST3GAL1 and ST3GAL2, which are critical for CD98hc stability in melanoma. Profiling miRNA regulation using our high-throughput miRFluR assay, we identified miRNA that up-regulated the expression of both CD98hc and either ST3GAL1 or ST3GAL2. These co-up-regulating miRNAs were enriched in melanoma datasets associated with transformation and progression. Our findings add co-up-regulation by miRNA into miRNA regulatory networks and add a bidirectional twist to the impact miRNAs have on protein regulation and glycosylation.

MUC1 expression is associated with ST3GAL2 and negatively correlated with the androgen receptor in castration-resistant prostate cancer

Stage-specific embryonic antigen-4 (SSEA-4) is a developmentally regulated antigen, while expression level of SSEA-4 and / or its synthase ST3GAL2 is associated with prognosis in various malignancies. We have reported a prominent increase of SSEA-4 in castration-resistant prostate cancer (CRPC) and its negative correlation with the androgen receptor (AR). Meanwhile, loss of AR has increased to approximately 30% with the growing use of androgen receptor signaling inhibitor for metastatic CRPC (mCRPC). However, monitoring the progression status of AR-negative prostate cancer is a challenge because it does not produce prostate-specific antigen. Based on the negative relationship of expression between AR and SSEA-4, we hypothesized that a soluble molecule synchronized with SSEA-4 in expression could be a serum marker candidate for AR-negative prostate cancer. Thus, we investigated the molecular background of SSEA-4 expression by ST3GAL2-knockout in DU145 cells. Here we show that MUC1 is identified as a molecule associated with ST3GAL2 and expressed in AR-negative prostate cancer. A negative correlation of expression between AR and MUC1 was observed in prostate cancer cell lines and CRPC tissues. The average rate of MUC1 expression was nearly 60% in AR-negative prostate cancer cells in CRPC tissues. Level of serum CA15-3 (MUC1) was the highest in mCRPC among various stages and its higher level was associated with faster progression of mCRPC. Our results demonstrate that MUC1 is identified as a ST3GAL2-associated molecule and expressed in AR-negative CRPC cells. Furthermore, level of serum CA15-3 may reflect the progression status of mCRPC.

CAR-T therapy for ovarian cancer: Recent advances and future directions

Ovarian cancer (OC) is a common gynecological tumor with high mortality, which is difficult to control its progression with conventional treatments and is prone to recurrence. Recent studies have identified OC as an immunogenic tumor that can be recognized by the host immune system. Immunotherapy for OC is being evaluated, but approaches such as immune checkpoint inhibitors have limited efficacy, adoptive cell therapy is an alternative therapy, in which CAR(chimeric antigen receptor)-T therapy has been applied to the clinical treatment of hematological malignancies. In addition, CAR-NK and CAR-macrophage (CAR-M) have also shown great potential in the treatment of solid tumors. Here, we discuss recent advances in preclinical and clinical studies of CAR-T for OC treatment, introduce the efforts made by researchers to modify the structure of CAR in order to achieve effective OC immunotherapy, as well as the research status of CAR-NK and CAR-M, and highlight emerging therapeutic opportunities that can be utilized to improve the survival of patients with OC using CAR-based adoptive cell therapy.

Phage Display as a Medium for Target Therapy Based Drug Discovery, Review and Update

Phage libraries are now amongst the most prominent approaches for the identification of high-affinity antibodies/peptides from billions of displayed phages in a specific library through the biopanning process. Due to its ability to discover potential therapeutic candidates that bind specifically to targets, phage display has gained considerable attention in targeted therapy. Using this approach, peptides with high-affinity and specificity can be identified for potential therapeutic or diagnostic use. Furthermore, phage libraries can be used to rapidly screen and identify novel antibodies to develop immunotherapeutics. The Food and Drug Administration (FDA) has approved several phage display-derived peptides and antibodies for the treatment of different diseases. In the current review, we provided a comprehensive insight into the role of phage display-derived peptides and antibodies in the treatment of different diseases including cancers, infectious diseases and neurological disorders. We also explored the applications of phage display in targeted drug delivery, gene therapy, and CAR T-cell.

Ganglioside SSEA-4 in Ewing sarcoma marks a tumor cell population with aggressive features and is a potential cell-surface immune target

Carbohydrate markers of immature cells during prenatal human development can be aberrantly expressed in cancers and deserve evaluation as immune targets. A candidate target in Ewing sarcoma is the globo-series ganglioside stage-specific embryonic antigen-4 (SSEA-4). We detected SSEA-4 expression on the cell surface of all of 14 EwS cell lines and in 21 of 31 (68%) primary EwS tumor biopsies. Among paired subpopulations of tumor cells with low versus high SSEA-4 expression, SSEA-4high expression was significantly and consistently associated with functional characteristics of tumor aggressiveness, including higher cell proliferation, colony formation, chemoresistance and propensity to migrate. SSEA-4low versus SSEA-4high expression was not related to expression levels of the EWSR1-FLI1 fusion transcript or markers of epithelial/mesenchymal plasticity. SSEA-4low cells selected from bulk populations regained higher SSEA-4 expression in vitro and during in vivo tumor growth in a murine xenograft model. T cells engineered to express SSEA-4-specific chimeric antigen receptors (CARs) specifically interacted with SSEA-4 positive EwS cells and exerted effective antigen-specific tumor cell lysis in vitro. In conclusion, with its stable expression and functional significance in EwS, SSEA-4 is an attractive therapeutic immune target in this cancer that deserves further evaluation for clinical translation.

Increased expression of SSEA-4 on TKI-resistant non-small cell lung cancer with EGFR-T790M mutation

Non-small cell lung cancer (NSCLC), a major life-threatening disease accounting for 85% of all lung cancer cases, has been treated with tyrosine kinase inhibitors (TKIs), but often resulted in drug resistance, and approximately 60% of TKI-resistant cases are due to acquired secondary (epithelial growth factor receptor) EGFR-T790M mutation. To identify alternative targets for TKI-resistant NSCLC with EGFR-T790M mutation, we found that the three globo-series glycosphingolipids are increasingly expressed on this type of NSCLC cell lines, and among them, the increase of stage-specific embryonic antigen-4 (SSEA-4) expression is the most significant. Compared to TKI-sensitive cell lines, SSEA-4 and the key enzyme β3GalT5 responsible for the synthesis of SSEA3 are more expressed in TKI-resistant NSCLC cell lines with EGFR-T790M mutation, and the expression levels strongly correlate with poor survival in patients with EGFR mutation. In addition, we demonstrated that a SSEA-4 targeted monoclonal antibody, especially the homogeneous glycoform with well-defined Fc glycan designed to improve effective functions, is highly effective against this subpopulation of NSCLC in cell-based and animal studies. These findings provide a direction for the prediction of tumor recurrence and treatment of TKI-resistant NSCLC with EGFR-T790M mutation.

Tumor immune microenvironment-based therapies in pancreatic ductal adenocarcinoma: time to update the concept

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumors. The tumor immune microenvironment (TIME) formed by interactions among cancer cells, immune cells, cancer-associated fibroblasts (CAF), and extracellular matrix (ECM) components drives PDAC in a more immunosuppressive direction: this is a major cause of therapy resistance and poor prognosis. In recent years, research has advanced our understanding of the signaling mechanism by which TIME components interact with the tumor and the evolution of immunophenotyping. Through revolutionary technologies such as single-cell sequencing, we have gone from simply classifying PDACs as "cold" and "hot" to a more comprehensive approach of immunophenotyping that considers all the cells and matrix components. This is key to improving the clinical efficacy of PDAC treatments. In this review, we elaborate on various TIME components in PDAC, the signaling mechanisms underlying their interactions, and the latest research into PDAC immunophenotyping. A deep understanding of these network interactions will contribute to the effective combination of TIME-based therapeutic approaches, such as immune checkpoint inhibitors (ICI), adoptive cell therapy, therapies targeting myeloid cells, CAF reprogramming, and stromal normalization. By selecting the appropriate integrated therapies based on precise immunophenotyping, significant advances in the future treatment of PDAC are possible.

Efficacy and Safety of Glycosphingolipid SSEA-4 Targeting CAR-T Cells in an Ovarian Carcinoma Model

Chimeric antigen receptor (CAR) T-cell immunotherapies for solid tumors face critical challenges such as heterogeneous antigen expression. We characterized stage-specific embryonic antigen-4 (SSEA-4) cell-surface glycolipid as a target for CAR T-cell therapy. SSEA-4 is mainly expressed during embryogenesis but is also found in several cancer types making it an attractive tumor-associated antigen. Anti-SSEA-4 CAR-T cells were generated and assessed preclinically in vitro and in vivo for antitumor response and safety. SSEA-4 CAR-T cells effectively eliminated SSEA-4-positive cells in all the tested cancer cell lines, whereas SSEA-4-negative cells lines were not targeted. In vivo efficacy and safety studies using NSG mice and the high-grade serous ovarian cancer cell line OVCAR4 demonstrated a remarkable and specific antitumor response at all the CAR T-cell doses used. At high T-cell doses, CAR T cell-treated mice showed signs of health deterioration after a follow-up period. However, the severity of toxicity was reduced with a delayed onset when lower CAR T-cell doses were used. Our data demonstrate the efficacy of anti-SSEA-4 CAR T-cell therapy; however, safety strategies, such as dose-limiting and/or equipping CAR-T cells with combinatorial antigen recognition should be implemented for its potential clinical translation.

Probing the Internalization and Efficacy of Antibody-Drug Conjugate via Site-Specific Fc-Glycan Labelling of a Homogeneous Antibody Targeting SSEA-4 Bearing Tumors

Antibody drug conjugates (ADC) are an emerging class of pharmaceuticals consisting of cytotoxic agents covalently attached to an antibody designed to target a specific cancer cell surface molecule followed by internalization and intracellular release of payload to exhibit its anticancer activity. Targeted delivery of cytotoxic payload to a variety of specific cells has been demonstrated to have significant enhancement in clinical efficacy and dramatic reduction in off-target toxicity. Site-specific conjugation of payload to the antibody is highly desirable for development of ADC with well-defined antibody-to-drug ratio, enhanced internalization, reduced toxicity, improved stability, desired pharmacological profile and optimal therapeutic index. Here, we reported a site-specific conjugation strategy for evaluation of antibody internalization and efficacy of ADC designed to target SSEA4 on solid tumors. This strategy stems from the azido-fucose tag of a homogeneous antibody Fc-glycan generated via in vitro glycoengineering approach for site-specific conjugation and optimization of antibody-drug ratio to exhibit optimal efficacy. The ADC consisting of a chimeric anti-SSEA4 antibody chMC813-70, conjugated to the antineo-plastic agent monomethyl auristatin E via both cleavable and non-cleavable linkers showed excellent cytotoxicity profile towards SSEA4-bearing cancer cells. A clear distinction in cytotoxicity was observed among cancer cells with different SSEA4 expression levels.

Analysis of EVs from patients with advanced pancreatic cancer identifies antigens and miRNAs with predictive value

The identification of predictive factors for treatment of pancreatic cancer (PC) is an unmet clinical need. In the present work, we analyzed blood-derived extracellular vesicles (EVs) from patients with advanced PC in order to find a molecular signature predictive of response to therapy. We analyzed samples from 21 patients with advanced PC, all receiving first-line treatment with gemcitabine + nab-paclitaxel. Isolated EVs have been analyzed, and the results of laboratory have been matched with clinical data in order to investigate possible predictive factors. EV concentration and size were similar between responder and non-responder patients. Analysis of 37 EV surface epitopes showed a decreased expression of SSEA4 and CD81 in responder patients. We detected more than 450 expressed miRNAs in EVs. A comparative survey between responder and non-responder patients showed that at least 44 miRNAs were differently expressed. Some of these miRNAs have already been observed in relation to the survival and gemcitabine sensitivity of tumor cells. In conclusion, we showed the ability of our approach to identify EV-derived biomarkers with predictive value for therapy response in PC. Our findings are worthy of further investigation, including the analysis of samples from patients treated with different schedules and in different settings.

Anti-glycan monoclonal antibodies: Basic research and clinical applications

Anti-glycan monoclonal antibodies have important applications in human health and basic research. Therapeutic antibodies that recognize cancer- or pathogen-associated glycans have been investigated in numerous clinical trials, resulting in two FDA-approved biopharmaceuticals. Anti-glycan antibodies are also utilized to diagnose, prognosticate, and monitor disease progression, as well as to study the biological roles and expression of glycans. High-quality anti-glycan mAbs are still in limited supply, highlighting the need for new technologies for anti-glycan antibody discovery. This review discusses anti-glycan monoclonal antibodies with applications to basic research, diagnostics, and therapeutics, focusing on recent advances in mAbs targeting cancer- and infectious disease-associated glycans.

Smaller size packs a stronger punch - Recent advances in small antibody fragments targeting tumour-associated carbohydrate antigens

Attached to proteins, lipids, or forming long, complex chains, glycans represent the most versatile post-translational modification in nature and surround all human cells. Unique glycan structures are monitored by the immune system and differentiate self from non-self and healthy from malignant cells. Aberrant glycosylations, termed tumour-associated carbohydrate antigens (TACAs), are a hallmark of cancer and are correlated with all aspects of cancer biology. Therefore, TACAs represent attractive targets for monoclonal antibodies for cancer diagnosis and therapy. However, due to the thick and dense glycocalyx as well as the tumour micro-environment, conventional antibodies often suffer from restricted access and limited effectiveness in vivo. To overcome this issue, many small antibody fragments have come forth, showing similar affinity with better efficiency than their full-length counterparts. Here we review small antibody fragments against specific glycans on tumour cells and highlight their advantages over conventional antibodies.

Study on antibody Fc-glycosylation for optimal effector functions

A comprehensive structure-activity relationship study on antibody Fc-glycosylation has been performed using the chimeric anti-SSEA4 antibody chMC813-70 as a model. The α-2,6 sialylated biantennary complex type glycan was identified as the optimal Fc-glycan with significant enhancement in antibody effector functions, including binding to different Fc receptors and ADCC.

Targeting Tn-positive tumors with an afucosylated recombinant anti-Tn IgG

The aberrant expression of the Tn antigen (CD175) on surface glycoproteins of human carcinomas is associated with tumorigenesis, metastasis, and poor survival. To target this antigen, we developed Remab6, a recombinant, human chimeric anti-Tn-specific monoclonal IgG. However, this antibody lacks antibody-dependent cell cytotoxicity (ADCC) effector activity, due to core fucosylation of its N-glycans. Here we describe the generation of an afucosylated Remab6 (Remab6-AF) in HEK293 cells in which the FX gene is deleted (FXKO). These cells cannot synthesize GDP-fucose through the de novo pathway, and lack fucosylated glycans, although they can incorporate extracellularly-supplied fucose through their intact salvage pathway. Remab6-AF has strong ADCC activity against Tn+ colorectal and breast cancer cell lines in vitro, and is effective in reducing tumor size in an in vivo xenotransplant mouse model. Thus, Remab6-AF should be considered as a potential therapeutic anti-tumor antibody against Tn+ tumors.

Progress and prospects for use of cellular immunotherapy in pancreatic cancer

Pancreatic cancer (PC) is a highly malignant tumor with an increasing incidence rate in recent years. Because pancreatic cancer has an insidious onset, unknown pathophysiology, and poor prognosis, the overall survival rate of pancreatic cancer patients has not improved considerably even with extensive treatment methods such as surgery, radiation, biotherapy, and targeted therapy. Therefore, finding and developing more effective and safe treatments for pancreatic cancer is critical. Cellular immunotherapy has achieved considerable advances in the field of oncology in recent years. Technology is continuously advancing, with new breakthroughs virtually every month, and pancreatic cancer eradication is expected to improve considerably. This article examines the advance of chimeric antigen receptor NK cell immunotherapy (CAR-NK) cell immunotherapy for pancreatic cancer research, as well as research ideas for pancreatic cancer treatment.

CAR T cells equipped with a fully human scFv targeting Trop2 can be used to treat pancreatic cancer

PURPOSE

Chimeric antigen receptor (CAR) T cell therapy has demonstrated clinical success in treating haematologic malignancies but has not been effective against solid tumours thus far. Trop2 is a tumour-related antigen broadly overexpressed on a variety of tumours and has been reported as a promising target for pancreatic cancers. Our study aimed to determine whether CAR T cells designed with a fully human Trop2-specific single-chain fragment variable (scFv) can be used in the treatment of Trop2-positive pancreatic tumours.

METHODS

We designed Trop2-targeted chimeric antigen receptor engineered T cells with a novel human anti-Trop2 scFv (2F11) and then investigated the cytotoxicity, degranulation, and cytokine secretion profiles of the anti-Trop2 CAR T cells when they were exposed to Trop2 + cancer cells in vitro. We also studied the antitumour efficacy and toxicity of Trop2-specific CAR T cells in vivo using a BxPC-3 pancreatic xenograft model.

RESULTS

Trop2-targeted CAR T cells designed with 2F11 effectively killed Trop2-positive pancreatic cancer cells and produced high levels of cytotoxic cytokines in vitro. In addition, Trop2-targeted CAR T cells, which persistently circulate in vivo and efficiently infiltrate into tumour tissues, significantly blocked and even eliminated BxPC-3 pancreatic xenograft tumour growth without obvious deleterious effects observed after intravenous injection into NSG mice. Moreover, disease-free survival was efficiently prolonged.

CONCLUSION

These results show that Trop2-targeted CAR T cells equipped with a fully human anti-Trop2 scFv could be a potential treatment strategy for pancreatic cancer and could be useful for clinical evaluation.