Targeted killing of colorectal cancer cell lines by a humanised IgG1 monoclonal antibody that binds to membrane-bound carcinoembryonic antigen

Tumor resistance to anti-mesothelin CAR-T cells caused by binding to shed mesothelin is overcome by targeting a juxtamembrane epitope

Despite many clinical trials, CAR-T cells are not yet approved for human solid tumor therapy. One popular target is mesothelin (MSLN) which is highly expressed on the surface of about 30% of cancers including mesothelioma and cancers of the ovary, pancreas, and lung. MSLN is shed by proteases that cleave near the C terminus, leaving a short peptide attached to the cell. Most anti-MSLN antibodies bind to shed MSLN, which can prevent their binding to target cells. To overcome this limitation, we developed an antibody (15B6) that binds next to the membrane at the protease-sensitive region, does not bind to shed MSLN, and makes CAR-T cells that have much higher anti-tumor activity than a CAR-T that binds to shed MSLN. We have now humanized the Fv (h15B6), so the CAR-T can be used to treat patients and show that h15B6 CAR-T produces complete regressions in a hard-to-treat pancreatic cancer patient derived xenograft model, whereas CAR-T targeting a shed epitope (SS1) have no anti-tumor activity. In these pancreatic cancers, the h15B6 CAR-T replicates and replaces the cancer cells, whereas there are no CAR-T cells in the tumors receiving SS1 CAR-T. To determine the mechanism accounting for high activity, we used an OVCAR-8 intraperitoneal model to show that poorly active SS1-CAR-T cells are bound to shed MSLN, whereas highly active h15B6 CAR-T do not contain bound MSLN enabling them to bind to and kill cancer cells.

Adjuvant properties of IFN-γ and GM-CSF in the scFv6.C4 DNA vaccine against CEA-expressing tumors

Tumor-associated carcinoembryonic antigen (CEA) is a natural target for vaccines against colorectal cancers. Our previous experience with a DNA vaccine with scFv6.C4, a CEA surrogate, showed a CEA-specific immune response with 40% of tumor-free mice after challenge with B16F10-CEA and 47% with MC38-CEA cells. These percentages increased to 63% after using FrC as an adjuvant. To further enhance the vaccine efficacy, we tested GM-CSF and IFNγ as adjuvants. C57BL/6J-CEA2682 mice were immunized 4 times with uP-PS/scFv6.C4, uP-PS/scFv6.C4 + uP-IFNγ, or uP-PS/scFv6.C4 + uP-GMCSF. After one week, the mice were challenged with MC38-CEA, and tumor growth was monitored over 100 days. Immunization with scFv6.C4 and scFv6.C4 + GM-CSF resulted in a gradual increase in the anti-CEA antibody titer, while scFv6.C4 + IFNγ immunization led to a rapid and sustained increase in the titer. The addition of IFNγ also induced higher CD4 + and CD8 + responses. When challenged, almost 80% of the scFv6.C4 + IFNγ-vaccinated mice did not develop tumors, while the others had a significant tumor growth delay. The probability of being tumor-free was 2700% higher using scFv6.C4 + IFNγ than scFv6.C4. The addition of GM-CSF had no additional effect on tumor protection. DNA immunization with scFv6.C4 + IFNγ, but not GM-CSF, increased the antitumor effect via readily sustained specific humoral and cytotoxic responses to CEA.

CEACAMS 1, 5, and 6 in disease and cancer: interactions with pathogens

The CEA family comprises 18 genes and 11 pseudogenes located at chromosome 19q13.2 and is divided into two main groups: cell surface anchored CEA-related cell adhesion molecules (CEACAMs) and the secreted pregnancy-specific glycoproteins (PSGs). CEACAMs are highly glycosylated cell surface anchored, intracellular, and intercellular signaling molecules with diverse functions, from cell differentiation and transformation to modulating immune responses associated with infection, inflammation, and cancer. In this review, we explore current knowledge surrounding CEACAM1, CEACAM5, and CEACAM6, highlight their pathological significance in the areas of cancer biology, immunology, and inflammatory disease, and describe the utility of murine models in exploring questions related to these proteins.

Immunotherapeutic progress and application of bispecific antibody in cancer

Bispecific antibodies (bsAbs) are artificial antibodies with two distinct antigen-binding sites that can bind to different antigens or different epitopes on the same antigen. Based on a variety of technology platforms currently developed, bsAbs can exhibit different formats and mechanisms of action. The upgrading of antibody technology has promoted the development of bsAbs, which has been effectively used in the treatment of tumors. So far, 7 bsAbs have been approved for marketing in the world, and more than 200 bsAbs are in clinical and preclinical research stages. Here, we summarize the development process of bsAbs, application in tumor treatment and look forward to the challenges in future development.

Antibody drug conjugates in gastrointestinal cancer: From lab to clinical development

The antibody-drug conjugates (ADCs) are one the fastest growing biotherapeutics in oncology and are still in their infancy in gastrointestinal (GI) cancer for clinical applications to improve patient survival. The ADC based approach is developed with tumor specific antigen, antibody carrying cytotoxic agents to precisely target and deliver chemotherapeutics at the tumor site. To date, 11 ADCs have been approved by US-FDA, and more than 80 are in the clinical development phase for different oncological indications. However, The ADCs based therapies in GI cancers are still far from having high-efficient clinical outcomes. The limited success of these ADCs and lessons learned from the past are now being used to develop a newer generation of ADC against GI cancers. In this review, we did a comprehensive assessment of the key components of ADCs, including tumor marker, antibody, cytotoxic payload, and linkage strategy, with a focus on technical improvement and some future trends in the pipeline for clinical translation. The various preclinical and clinical ADCs used in gastrointestinal malignancies, their target, composition and bioconjugation, along with preclinical and clinical outcomes, are discussed. The emphasis is also given to new generation ADCs employing novel mAb, payload, linker, and bioconjugation methods are also included.

Structural design of tetravalent T-cell engaging bispecific antibodies: improve developability by engineering disulfide bonds

Since the advances in protein engineering and manufacture, over the last 30 years, antibody-based immunotherapeutic has become a powerful strategy to treat diseases. The T-cell engaging bispecific antibody (BsAb) by combining the Fab binding domain of tumor antigens and Fab or single-chain variable fragments (scFvs) binding domain of CD3 molecules, could redirect cytotoxic T cells to kill tumor cells. The IgG-scFv format of BsAb is a dual bivalent and asymmetrical design, which adds the benefit of potent cytotoxicity and less complicated for manufacture but limits the stability and production. Here, we engineered a series of interchain disulfide bonds in the Fab region of IgG-svFv BsAbs and evaluated its biophysical and biological properties. We found that simultaneously replaced the position of VH44-VL100 and CH1126-CL121 residues with cysteine, to form two additional disulfide bonds, could markedly increase monomeric BsAb formation and yield. The thermostability and stability against aggregation and degradation also performed better than BsAbs without extra disulfide bonds introduction. Besides, the affinity of engineered BsAbs was maintained, and the h8B-BsAb antibody had a slight enhancement in an inhibitory effect on target cells.

Proteomic Profiling of Gastric Signet Ring Cell Carcinoma Tissues Reveals Characteristic Changes of the Complement Cascade Pathway

Signet ring cell carcinoma (SRCC) is a histological subtype of gastric cancer with distinct features in multiple aspects compared with adenocarcinomas (ACs). The lack of a systematic molecular overview of this disease has led to slow progress in its clinical practice. In the present proteomics study, gastric tissues were collected from tumors and adjacent tissues, including 14 SRCCs and 34 ACs, and laser capture microdissection (LCM) was employed to eradicate the cellular heterogeneity of the tissues. The proteomes of tissues were profiled by data-independent acquisition (DIA) mass spectrometry (MS). Based on the over 6000 proteins quantified, univariate analysis and pathway enrichment revealed that some proteins and pathways demonstrated differences between SRCC and ACs. Importantly, the upregulation of a majority of complement-related proteins was notable for SRCC but not for ACs. A hypothesis, based on the proteomics evidence, was proposed that the complement cascade was evoked in the SRCC microenvironment upon infiltration, and the SRCC cells survived the complement cytotoxicity by secreting endogenous negative regulators. Moreover, an attempt was made to establish appropriate cell models for gastric SRCC through proteomic comparison of the 15 gastric cell lines and gastric tumors. The predictions of a supervised classifier suggested that none of these gastric cell lines qualified to mimic SRCC. This study discovered that the complement cascade is activated at a higher level in gastric SRCC than in ACs.

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LCM-DIA extracted unprecedented proteomic details of gastric in different subtypes.

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Complement cascade was found to be an SRCC-specific pathway for the first time.

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Gastric cell lines were evaluated based on proteomic features for the first time.

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Re-analyzable DIA data collected provide rich opportunity for future research.

Immuno-PET Imaging and Pharmacokinetics of an Anti-CEA scFv-based Trimerbody and Its Monomeric Counterpart in Human Gastric Carcinoma-Bearing Mice

Monoclonal antibodies (mAbs) are currently used as therapeutic agents in different types of cancer. However, mAbs and antibody fragments developed so far show suboptimal properties in terms of circulation time and tumor penetration/retention. Here, we report the radiolabeling, pharmacokinetic evaluation, and determination of tumor targeting capacity of the previously validated anti-CEA MFE23-scFv-based N-terminal trimerbody (MFE23^N-trimerbody), and the results are compared to those obtained for the monomeric MFE23-scFv. Dissection and gamma-counting studies performed with the ¹³¹I-labeled protein scaffolds in normal mice showed slower blood clearance for the trimerbody, and accumulation in the kidneys, the spleen, and the liver for both species. These, together with a progressive uptake in the small intestine, confirm a combined elimination scheme with hepatobiliary and urinary excretion. Positron emission tomography studies performed in a xenograft mouse model of human gastric adenocarcinoma, generated by subcutaneous administration of CEA-positive human MKN45 cells, showed higher tumor accumulation and tumor-to-muscle (T/M) ratios for ¹²⁴I-labeled MFE23^N-trimerbody than for MFE23-scFv. Specific uptake was not detected with PET imaging in CEA negative xenografts as indicated by low T/M ratios. Our data suggest that engineered intermediate-sized trivalent antibody fragments could be promising candidates for targeted therapy and imaging of CEA-positive tumors.

A nanobody targeting carcinoembryonic antigen as a promising molecular probe for non-small cell lung cancer

Carcinoembryonic antigen (CEA) is a biomarker and therapy target for non-small cell lung cancer (NSCLC), which is the most common type of lung cancer. Nanobodies with high target specificity are promising candidates to function as anti-CEA probes. In the present study, the targeting effects of an anti-CEA nanobody obtained from phage display were investigated using technetium-99 m (^99mTc) and fluorescence labeling. In vitro binding and immunofluorescent staining assays, as well as in vivo blood clearance and biodistribution assays were performed. High specificity and affinity of the nanobody for CEA-positive H460 cells was observed in vitro. The pharmacokinetics assay of the ^99mTc-nanobody in Wistar rats demonstrated that the nanobody had appropriate T_1/2α and T_1/2β, which were 20.2 and 143.5 min, respectively. The biodistribution assay using H460 xenograft-bearing nude mice demonstrated a high ratio of signal in tumor compared with background, which confirmed that the nanobody may be useful as a molecular probe for CEA-positive cancer, particularly in NSCLC.

Novel anticarcinoembryonic antigen antibody-drug conjugate has antitumor activity in the existence of soluble antigen

Carcinoembryonic antigen (CEA) is a classic tumor‐specific antigen that is overexpressed in several cancers, including gastric cancer. Although some anti‐CEA antibodies have been tested, to the best of our knowledge, there are currently no clinically approved anti‐CEA antibody therapies. Because of this, we have created the novel anti‐CEA antibody, 15‐1‐32, which exhibits stronger binding to membrane‐bound CEA on cancer cells than existing anti‐CEA antibodies. 15‐1‐32 also shows poor affinity for soluble CEA; thus, the binding activity of 15‐1‐32 to membrane‐bound CEA is not influenced by soluble CEA. In addition, we constructed a 15‐1‐32‐monomethyl auristatin E conjugate (15‐1‐32‐vcMMAE) to improve the therapeutic efficacy of 15‐1‐32. 15‐1‐32‐vcMMAE showed enhanced antitumor activity against gastric cancer cell lines. Unlike with existing anti‐CEA antibody therapies, antitumor activity of 15‐1‐32‐vcMMAE was retained in the presence of high concentrations of soluble CEA.

Targeted nanoparticles for colorectal cancer

Colorectal cancer (CRC) is highly prevalent worldwide, and despite notable progress in treatment still leads to significant morbidity and mortality. The use of nanoparticles as a drug delivery system has become one of the most promising strategies for cancer therapy. Targeted nanoparticles could take advantage of differentially expressed molecules on the surface of tumor cells, providing effective release of cytotoxic drugs. Several efforts have recently reported the use of diverse molecules as ligands on the surface of nanoparticles to interact with the tumor cells, enabling the effective delivery of antitumor agents. Here, we present recent advances in targeted nanoparticles against CRC and discuss the promising use of ligands and cellular targets in potential strategies for the treatment of CRCs.

Carcinoembryonic antigen is the preferred biomarker for in vivo colorectal cancer targeting

Background:

Colorectal cancer-specific biomarkers have been used as molecular targets for fluorescent intra-operative imaging, targeted PET/MRI, and selective cytotoxic drug delivery yet the selection of biomarkers used is rarely evidence-based. We evaluated sensitivities and specificites of four of the most commonly used markers: carcinoembryonic antigen (CEA), tumour-associated glycoprotein-72 (TAG-72), folate receptor-α (FRα) and Epithelial growth factor receptor (EGFR).

Methods:

Marker expression was evaluated semi-quantitatively in matched mucosal and colorectal cancer tissues from 280 patients using immunohistochemistry (scores of 0–15). Matched positive and negative lymph nodes from 18 patients were also examined.

Results:

Markers were more highly expressed in tumour tissue than in matched normal tissue in 98.8%, 79.0%, 37.1% and 32.8% of cases for CEA, TAG-72, FRα and EGFR, respectively. Carcinoembryonic antigen showed the greatest differential expression, with tumours scoring a mean of 10.8 points higher than normal tissues (95% CI 10.31–11.21, P<0.001). Similarly, CEA showed the greatest differential expression between positive and negative lymph nodes. Receiver operating characteristic analyses showed CEA to have the best sensitivity (93.7%) and specificity (96.1%) for colorectal cancer detection.

Conclusion:

Carcinoembryonic antigen has the greatest potential to allow highly specific tumour imaging and drug delivery; future translational research should aim to exploit this.

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.

Targeted immunotherapy for colorectal cancer: monoclonal antibodies and immunotoxins

Colorectal cancer (CRC) is a major health concern worldwide. It is the third most frequently diagnosed cancer and the second leading cause of cancer death. There currently are a number of treatment options for CRC, however many of them have failed to demonstrate desired therapeutic benefit. Therefore, significant efforts are being directed towards the development of new biological therapies with improved efficacy. Immunotherapy is an emerging treatment modality for a variety of cancers. Several promising treatments have already been approved by the US FDA and are being tested in clinical trials. Antibodies have been proved to be useful in cancer therapy due to their ability to recognize tumor-associated antigens expressed at higher density on malignant cells in comparison with those that are normal. Antibodies can be used as a single therapy or in combination with other therapies. A large variety of monoclonal antibodies have been developed. However, only a very few are able to kill a sufficient number of malignant cells and cause tumor regression. Hence, it is often necessary to arm the antibody with a cytotoxic agent to enhance the efficacy of the anti-tumor activity. This review provides a brief overview of some of the current agents being employed in targeted immunotherapy for CRC.

Humanised IgG1 antibody variants targeting membrane-bound carcinoembryonic antigen by antibody-dependent cellular cytotoxicity and phagocytosis

BACKGROUND

The effect of glycoengineering a membrane specific anti-carcinoembryonic antigen (CEA) (this paper uses the original term CEA for the formally designated CEACAM5) antibody (PR1A3) on its ability to enhance killing of colorectal cancer (CRC) cell lines by human immune effector cells was assessed. In vivo efficacy of the antibody was also tested.

METHODS

The antibody was modified using EBNA cells cotransfected with beta-1,4-N-acetylglucosaminyltransferase III and the humanised hPR1A3 antibody genes.

RESULTS

The resulting alteration of the Fc segment glycosylation pattern enhances the antibody's binding affinity to the FcgammaRIIIa receptor on human immune effector cells but does not alter the antibody's binding capacity. Antibody-dependent cellular cytotoxicity (ADCC) is inhibited in the presence of anti-FcgammaRIII blocking antibodies. This glycovariant of hPR1A3 enhances ADCC 10-fold relative to the parent unmodified antibody using either unfractionated peripheral blood mononuclear or natural killer (NK) cells and CEA-positive CRC cells as targets. NK cells are far more potent in eliciting ADCC than either freshly isolated monocytes or granulocytes. Flow cytometry and automated fluorescent microscopy have been used to show that both versions of hPR1A3 can induce antibody-dependent cellular phagocytosis (ADCP) by monocyte-derived macrophages. However, the glycovariant antibody did not mediate enhanced ADCP. This may be explained by the relatively low expression of FcgammaRIIIa on cultured macrophages. In vivo studies show the efficacy of glycoengineered humanised IgG1 PR1A3 in significantly improving survival in a CRC metastatic murine model.

CONCLUSION

The greatly enhanced in vitro ADCC activity of the glycoengineered version of hPR1A3 is likely to be clinically beneficial.

One example on how colloidal nano- and microparticles could contribute to medicine

Nanomedicine, nowadays, is a popular keyword in the media, although everyone seems to associate it with different visions, hopes and even fears. This article gives a perspective from two sides. From the point of view of a materials scientist, it will be pointed out what new materials will be possible, how they will be designed and which properties they could offer for diagnosis and treatment. From the point of view of a medical doctor, it will be pointed out which properties are actually desired and what materials are hoped for practical applications. The two different points of view indicate that, although sophisticated materials with advanced novel properties will be available in the future, they do not automatically match the requirements and demands of clinicians. The discussion is centerd around one example, multifunctional polyelectrolyte capsules, which might act as a ‘nanosubmarine’ for in vivo sensing and delivery, which is used to highlight promising interfaces between both disciplines.

Monoclonal antibodies in the treatment of pancreatic cancer

Human pancreatic cancer is a malignant disease with almost equal incidence and mortality. Effective diagnostic and therapeutic strategies are still urgently needed to improve its survival rate. With advances in structural and functional genomics, recent work has focused on targeted molecular therapy using monoclonal antibodies. This review summarizes the target molecules on the tumor cell surface and normal tissue stroma, which are related to pancreatic cancer oncogenesis, tumor growth or resistance to chemotherapy, as well as molecules involved in regulating inflammation and host immunoresponses. Targeted molecules include cell-surface receptors, such as the EGF receptor, HER2, death receptor 5 and IGF-1 receptor. Effects of monoclonal antibodies against these target molecules alone or in combination with chemotherapy, small-molecule signal transduction inhibitors, or radiation therapy are also discussed. Also discussed are the use of toxin or radioisotope conjugates, and information relating to the use of these targeting agents in pancreatic cancer clinical trials. Although targeted molecular therapy with monoclonal antibodies has made some progress in pancreatic cancer treatment, especially in preclinical studies, its clinical application to improve the survival rate of pancreatic cancer patients requires further investigation.