CSPG4: A Target for Selective Delivery of Human Cytolytic Fusion Proteins and TRAIL

Pseudogene CSPG4P12 inhibits colorectal cancer progression by attenuating epithelial-mesenchymal transition

Colorectal cancer is one of the most common malignant cancers. Pseudogenes have been identified as oncogenes or tumor suppressor genes in the development of various cancers. However, the function of pseudogene CSPG4P12 in colorectal cancer remains unclear. Therefore, the aim of this study was to investigate the potential role of CSPG4P12 in colorectal cancer and explore the possible underlying mechanism. The difference of CSPG4P12 expression between colorectal cancer tissues and adjacent normal tissues was analyzed using the online Gene Expression Profiling Interactive Analysis 2 (GEPIA2) database. Cell viability and colony formation assays were conducted to evaluate cell viability. Transwell and wound healing assays were performed to assess cell migration and invasion capacities. Western blot was used to measure the expression levels of epithelial-mesenchymal transition-related proteins. Colorectal cancer tissues had lower CSPG4P12 expression than adjacent normal tissues. The overexpression of CSPG4P12 inhibited cell proliferation, invasion, and migration in colorectal cancer cells. Overexpressed CSPG4P12 promoted the expression of E-cadherin, whereas it inhibited the expression of vimentin, N-cadherin, and MMP9. These findings suggested that CSPG4P12 inhibits colorectal cancer development and may serve as a new potential target for colorectal cancer.

Chondroitin sulfate proteoglycan 4: An attractive target for antibody-based immunotherapy

Multifunctional molecules involved in tumor progression and metastasis have been identified as valuable targets for immunotherapy. Among these, chondroitin sulfate proteoglycan 4 (CSPG4), a significant tumor cell membrane-bound proteoglycan, has emerged as a promising target, especially in light of advances in chimeric antigen receptor (CAR) T-cell therapy. The profound bioactivity of CSPG4 and its role in pivotal processes such as tumor proliferation, migration, and neoangiogenesis underline its therapeutic potential. We reviewed the molecular intricacies of CSPG4, its functional attributes within tumor cells, and the latest clinical-translational advances targeting it. Strategies such as blocking monoclonal antibodies, conjugate therapies, bispecific antibodies, small-molecule inhibitors, CAR T-cell therapies, trispecific killer engagers, and ribonucleic acid vaccines against CSPG4 were assessed. CSPG4 overexpression in diverse tumors and its correlation with adverse prognostic outcomes emphasize its significance in cancer biology. These findings suggest that targeting CSPG4 offers a promising avenue for future cancer therapy, with potential synergistic effects when combined with existing treatments.

Immunohistochemical detection of the chondroitin sulfate proteoglycan 4 protein in primary and metastatic melanoma

Treatment of malignant melanoma, the most aggressive form of skin cancer, continues to be a major challenge for clinicians. New targeted therapies with kinase inhibitors or drugs which modify the immune response are often accompanied by the development of resistance or severe side effects. In this context, chondroitin sulfate proteoglycan 4 (CSPG4), a highly immunogenic melanoma tumor antigen, could be a potential target for alternative therapeutic approaches. The aim of the present study was to identify differences in the levels of CSPG4 protein expression in primary and metastatic melanomas as well as to analyze correlations between CSPG4 expression and histopathological data and patient characteristics. A total of 189 melanoma tissue samples from Lower Austria, including primary melanomas and melanoma metastases, were immunohistochemically stained for the expression of CSPG4 and statistical analyses were performed. A total of 65.6% of melanoma tissue samples stained positive for the expression of CSPG4. Primary nodular and primary superficial spreading melanomas demonstrated a significantly higher number of positively stained tissue samples for CSPG4 compared with primary lentigo maligna melanomas. No significant differences in the expression of CSPG4 were demonstrated between primary melanomas and melanoma metastases. The present study supports the advancement of the understanding of CSPG4 tissue expression patterns in melanoma patients and provides additional information for further investigation of CSPG4 as a potential therapeutic target.

Immunotherapeutic Targeting of NG2/CSPG4 in Solid Organ Cancers

Neuro-glia antigen 2/chondroitin sulfate proteoglycan 4 (NG2/CSPG4, also called MCSP, HMW-MAA, MSK16, MCSPG, MEL-CSPG, or gp240) is a large cell-surface antigen and an unusual cell membrane integral glycoprotein frequently expressed on undifferentiated precursor cells in multiple solid organ cancers, including cancers of the liver, pancreas, lungs, and kidneys. It is a valuable molecule involved in cancer cell adhesion, invasion, spreading, angiogenesis, complement inhibition, and signaling. Although the biological significance underlying NG2/CSPG4 proteoglycan involvement in cancer progression needs to be better defined, based on the current evidence, NG2/CSPG4⁺ cells, such as pericytes (PCs, NG2⁺/CD146⁺/PDGFR-β⁺) and cancer stem cells (CSCs), are closely associated with the liver malignancy, hepatocellular carcinoma (HCC), pancreatic malignancy, and pancreatic ductal adenocarcinoma (PDAC) as well as poor prognoses. Importantly, with a unique method, we successfully purified NG2/CSPG4-expressing cells from human HCC and PDAC vasculature tissue blocks (by core needle biopsy). The cells appeared to be spheres that stably expanded in cultures. As such, these cells have the potential to be used as sources of target antigens. Herein, we provide new information on the possibilities of frequently selecting NG2/CSPG4 as a solid organ cancer biomarker or exploiting expressing cells such as CSCs, or the PG/chondroitin sulfate chain of NG2/CSPG4 on the cell membrane as specific antigens for the development of antibody- and vaccine-based immunotherapeutic approaches to treat these cancers.

A proof-of-concept study on the use of a fluorescein-based 18F-tracer for pretargeted PET

Background

Pretargeted immuno-PET tumor imaging has emerged as a valuable diagnostic strategy that combines the high specificity of antibody-antigen interaction with the high signal and image resolution offered by short-lived PET isotopes, while reducing the irradiation dose caused by traditional ⁸⁹Zr-labelled antibodies. In this work, we demonstrate proof of concept of a novel ‘two-step’ immuno-PET pretargeting approach, based on bispecific antibodies (bsAbs) engineered to feature dual high-affinity binding activity for a fluorescein-based ¹⁸F-PET tracer and tumor markers.

Results

A copper(I)-catalysed click reaction-based radiolabeling protocol was developed for the synthesis of fluorescein-derived molecule [¹⁸F]TPF. Binding of [¹⁸F]TPF on FITC-bearing bsAbs was confirmed. An in vitro autoradiography assay demonstrated that [¹⁸F]TPF could be used for selective imaging of EpCAM-expressing OVCAR3 cells, when pretargeted with EpCAMxFITC bsAb. The versatility of the pretargeting approach was showcased in vitro using a series of fluorescein-binding bsAbs directed at various established cancer-associated targets, including the pan-carcinoma cell surface marker EpCAM, EGFR, melanoma marker MCSP (aka CSPG4), and immune checkpoint PD-L1, offering a range of potential future applications for this pretargeting platform.

Conclusion

A versatile pretargeting platform for PET imaging, which combines bispecific antibodies and a fluorescein-based ¹⁸F-tracer, is presented. It is shown to selectively target EpCAM-expressing cells in vitro and its further evaluation with different bispecific antibodies demonstrates the versatility of the approach.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41181-022-00155-2.

Exosome application in tumorigenesis: diagnosis and treatment of melanoma

Melanoma is the most aggressive of skin cancer derived from genetic mutations in the melanocytes. Current therapeutic approaches include surgical resection, chemotherapy, photodynamic therapy, immunotherapy, biochemotherapy, and targeted therapy. However, the efficiency of these strategies may be decreased due to the development of diverse resistance mechanisms. Here, it has been proven that therapeutic monoclonal antibodies (mAbs) can improve the efficiency of melanoma therapies and also, cancer vaccines are another approach for the treatment of melanoma that has already improved clinical outcomes in these patients. The use of antibodies and gene vaccines provides a new perspective in melanoma treatment. Since the tumor microenvironment is another important factor for cancer progression and metastasis, in recent times, a mechanism has been identified to provide an opportunity for melanoma cells to communicate with remote cells. This mechanism is involved by a novel molecular structure, named extracellular vesicles (EVs). Depending on the functional status of origin cells, exosomes contain various cargos and different compositions. In this review, we presented recent progress of exosome applications in the treatment of melanoma. Different aspects of exosome therapy and ongoing efforts in this field will be discussed too.

A chondroitin sulfate proteoglycan 4‑specific monoclonal antibody inhibits melanoma cell invasion in a spheroid model

The overexpression of chondroitin sulfate proteoglycan 4 (CSPG4) is associated with several tumor types, including malignant melanoma, squamous cell carcinoma, triple-negative breast carcinoma, oligodendrocytomas or gliomas. Due to its restricted distribution in normal tissues, CSPG4 has been considered a potential target for several antitumor approaches, including monoclonal antibody (mAb) therapies. The aim of the present study was to characterize the impact of the CSPG4-specific mAb clone 9.2.27 on its own or in combination with the commonly used BRAF-selective inhibitor, PLX4032, on different functions of melanoma cells to assess the potential synergistic effects. The BRAF V600-mutant human melanoma cell lines, M14 (CSPG4-negative) and WM164 (CSPG4-positive), were exposed to the CSPG4-specific 9.2.27 mAb and/or PLX4032. Cell viability and colony formation capacity were evaluated. A 3D-cell culture spheroid model was used to assess the invasive properties of the treated cells. In addition, flow cytometric analysis of apoptosis and cell cycle analyses were performed. Incubation of the WM164 cell line with CSPG4-specific 9.2.27 mAb decreased viability, colony formation ability and the invasive capacity of CSPG4-positive tumor cells, which was not the case for the CSPG4-negative M14 cell line. Combined treatment of the WM164 cells with 9.2.27 mAb plus PLX4032 did not exert any significant additional effect in comparison to treatment with PLX4032 alone in the clonogenic and invasion assays. M14 cell cycle distribution was not influenced by the CSPG4-specific 9.2.27 mAb. By contrast, the exposure of WM164 cells to the mAb resulted in an arrest of the cells in the S phase. Moreover, combined treatment of the WM164 cells led to a significantly increased accumulation of cells in the subG1 phase, combined with a decrease of cells in the G2/M phase. On the whole, findings of the present study indicate that the CSPG4-specific 9.2.27 mAb exerts an anti-invasive effect on CSPG4-positive melanoma spheroids, which is not enhanced by BRAF inhibition. These findings provide the basis for further investigations on the effects of anti-CSPG4-based treatments of CSPG4-positive tumors.

In Like a Lamb; Out Like a Lion: Marching CAR T Cells Toward Enhanced Efficacy in B-ALL

Combining synthetic biology with adoptive T-cell transfer has led to promising advances in the treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), diffuse large B-cell lymphoma (DLBCL), and mantle cell lymphoma (MCL). Chimeric antigen receptors (CARs) are synthetic receptors that redirect T-cell specificity against cancer. CARs include "built-in" signaling domains that reprogram T-cell metabolism, enhance effector function, and support long-term persistence. Despite their success in blood-based malignancies, relapse can occur in CD19-redirected CAR T-cell therapies for several reasons, including poor engraftment, impaired in vivo proliferation, and T-cell senescence. Herein, we explain how subtle alterations in CAR design may overcome barriers to effective adoptive immunotherapy. We also discuss how the physiochemical properties of the single-chain variable fragment (scFv) affect differentiation and persistence. Moreover, we describe innovative advances in CAR engineering and provide insight into the development of humanized scFvs whose proposed benefits include increased persistence and improved clinical outcomes. Tumor cells can evade CAR T-cell-mediated detection and elimination due to the emergence or presence of CD19-negative leukemic cell subpopulations. We also discuss the opportunities and challenges in targeting other B-ALL-associated antigens. Identifying alternate targets is fundamentally necessary to restore the success of CAR T-cell therapies in CD19-negative patients with B-ALL.

Expression of chondroitin sulfate proteoglycan 4 (CSPG4) in melanoma cells is downregulated upon inhibition of BRAF

Chondroitin sulfate proteoglycan 4 (CSPG4) is a multifunctional transmembrane proteoglycan involved in spreading, migration and invasion of melanoma. In addition to the activating BRAF V600E mutation, CSPG4 was shown to promote MAPK signaling by mediating the growth-factor induced activation of receptor tyrosine kinases. However, it remains elusive which factors regulate CSPG4 expression. Therefore, the aim of the present study was to examine whether BRAF and MEK inhibitors have an effect on the expression of CSPG4. We exposed a panel of BRAF-mutant CSPG4-positive or -negative melanoma cell lines to BRAF and MEK inhibitors. Protein levels of CSPG4 were analyzed by flow cytometry (FACS), immunofluorescence microscopy (IF), and western blotting. CSPG4 mRNA levels were determined by quantitative PCR (qPCR). The prolonged exposure of cells to BRAF and MEK inhibitors resulted in markedly reduced levels of the CSPG4 protein in permanent resistant melanoma cells as well as decreased levels of its mRNA. We did not observe increasing levels of CSPG4 shedding into the culture supernatants. In addition, patient-derived matched tumor samples following therapy with kinase inhibitors showed decreased numbers of CSPG4-positive cells as compared to pre-therapy tumor samples. Our results indicate that BRAF and MEK inhibition downregulates CSPG4 expression until the cells have developed permanent resistance. Our findings provide the basis for further investigation of the role of CSPG4 in the development of drug-resistance in melanoma cells.

Electroporation-Based Treatments in Small Animal Veterinary Oral and Maxillofacial Oncology

Electroporation is a method of inducing an increase in permeability of the cell membrane through the application of an electric field and can be used as a delivery method for introducing molecules of interest (e.g., chemotherapeutics or plasmid DNA) into cells. Electroporation-based treatments (i.e., electrochemotherapy, gene electrotransfer, and their combinations) have been shown to be safe and effective in veterinary oncology, but they are currently mostly recommended for the treatment of those solid tumors for which clients have declined surgery and/or radiotherapy. Published data show that electroporation-based treatments are also safe, simple, fast and cost-effective treatment alternatives for selected oral and maxillofacial tumors, especially small squamous cell carcinoma and malignant melanoma tumors not involving the bone in dogs. In these patients, a good local response to treatment is expected to result in increased survival time with good quality of life. Despite emerging evidence of the clinical efficacy of electroporation-based treatments for oral and maxillofacial tumors, further investigation is needed to optimize treatment protocols, improve clinical data reporting and better understand the mechanisms of patients' response to the treatment.

Advances in epidermal growth factor receptor specific immunotherapy: lessons to be learned from armed antibodies

The epidermal growth factor receptor (EGFR) has been recognized as an important therapeutic target in oncology. It is commonly overexpressed in a variety of solid tumors and is critically involved in cell survival, proliferation, metastasis, and angiogenesis. This multi-dimensional role of EGFR in the progression and aggressiveness of cancer, has evolved from conventional to more targeted therapeutic approaches. With the advent of hybridoma technology and phage display techniques, the first anti-EGFR monoclonal antibodies (mAbs) (Cetuximab and Panitumumab) were developed. Due to major limitations including host immune reactions and poor tumor penetration, these antibodies were modified and used as guiding mechanisms for the specific delivery of readily available chemotherapeutic agents or plants/bacterial toxins, giving rise to antibody-drug conjugates (ADCs) and immunotoxins (ITs), respectively. Continued refinement of ITs led to deimmunization strategies based on depletion of B and T-cell epitopes or substitution of non-human toxins leading to a growing repertoire of human enzymes capable of inducing cell death. Similarly, the modification of classical ADCs has resulted in the first, fully recombinant versions. In this review, we discuss significant advancements in EGFR-targeting immunoconjugates, including ITs and recombinant photoactivable ADCs, which serve as a blueprint for further developments in the evolving domain of cancer immunotherapy.

Chondroitin Sulphate Proteoglycans in the Tumour Microenvironment

Proteoglycans are macromolecules that are essential for the development of cells, human diseases and malignancies. In particular, chondroitin sulphate proteoglycans (CSPGs) accumulate in tumour stroma and play a key role in tumour growth and invasion by driving multiple oncogenic pathways in tumour cells and promoting crucial interactions in the tumour microenvironment (TME). These pathways involve receptor tyrosine kinase (RTK) signalling via the mitogen-activated protein kinase (MAPK) cascade and integrin signalling via the activation of focal adhesion kinase (FAK), which sustains the activation of extracellular signal-regulated kinases 1/2 (ERK1/2).Human CSPG4 is a type I transmembrane protein that is associated with the growth and progression of human brain tumours. It regulates cell signalling and migration by interacting with components of the extracellular matrix, extracellular ligands, growth factor receptors, intracellular enzymes and structural proteins. Its overexpression by tumour cells, perivascular cells and precursor/progenitor cells in gliomas suggests that it plays a role in their origin, progression and neo-angiogenesis and its aberrant expression in tumour cells may be a promising biomarker to monitor malignant progression and patient survival.The aim of this chapter is to review and discuss the role of CSPG4 in the TME of human gliomas, including its potential as a druggable therapeutic target.

Clinical-Scale Production of CAR-T Cells for the Treatment of Melanoma Patients by mRNA Transfection of a CSPG4-Specific CAR under Full GMP Compliance

Chimeric antigen receptor (CAR)-T cells already showed impressive clinical regressions in leukemia and lymphoma. However, the development of CAR-T cells against solid tumors lags behind. Here we present the clinical-scale production of CAR-T cells for the treatment of melanoma under full GMP compliance. In this approach a CAR, specific for chondroitin sulfate proteoglycan 4 (CSPG4) is intentionally transiently expressed by mRNA electroporation for safety reasons. The clinical-scale protocol was optimized for: (i) expansion of T cells, (ii) electroporation efficiency, (iii) viability, (iv) cryopreservation, and (v) potency. Four consistency runs resulted in CAR-T cells in clinically sufficient numbers, i.e., 2.4 × 10⁹ CAR-expressing T cells, starting from 1.77x10⁸ PBMCs, with an average expansion of 13.6x, an electroporation efficiency of 88.0% CAR-positive cells, a survival of 74.1% after electroporation, and a viability of 84% after cryopreservation. Purity was 98.7% CD3⁺ cells, with 78.1% CD3⁺/CD8⁺ T cells and with minor contaminations of 1.2% NK cells and 0.6% B cells. The resulting CAR-T cells were tested for cytolytic activity after cryopreservation and showed antigen-specific and very efficient lysis of tumor cells. Although our work is descriptive rather than investigative in nature, we expect that providing this clinically applicable protocol to generate sufficient numbers of mRNA-transfected CAR-T cells will help in moving the field of adoptive cell therapy of cancer forward.

CSPG4-Specific CAR T Cells for High-Risk Childhood B Cell Precursor Leukemia

The advent of CD19-specific chimeric antigen receptor (CAR) T cells has proven to be a powerful asset in the arsenal of cancer immunotherapy of acute lymphoblastic leukemia and certain B cell lymphomas. However, a sizable portion of patients treated with CD19-CAR T cells relapse with CD19-negative cancer cells, necessitating the quest for back-up antigens. Chondroitin sulfate proteoglycan 4 (CSPG4) expression has been reported on leukemic blasts bearing the ill-fated MLL 11q23 rearrangement. We aimed at exploring the use of CSPG4-specific CAR T cells against mixed-lineage leukemia (MLL)-rearranged leukemic blasts, using the precursor B cell leukemia cell line KOPN8 (MLL–MLLT1 translocation) as a model. First, we confirmed CSPG4 expression on KOPN8 cells. Bulk T cells electroporated with mRNA encoding a CSPG4-specific CAR upregulated activation markers and secreted the Th1 cytokines TNF and IFNγ in an antigen-specific manner upon co-culture with KOPN8 cells. More importantly, CSPG4-specific CAR T cells evinced specific degranulation towards KOPN8 cells and specifically lysed KOPN8 target cells in chromium lysis experiments. CSPG4 is a well-established CAR target in cutaneous melanoma. Here, we provide proof-of-principle data for the use of CSPG4-specific CAR T cells against MLL-translocated leukemias.

Bispecific Antibody Approach for Improved Melanoma-Selective PD-L1 Immune Checkpoint Blockade

Reactivation of functionally-impaired anticancer T cells by programmed cell death protein 1 (PD-1) and programmed cell death receptor ligand-1 (PD-L1)-blocking antibodies shows prominent therapeutic benefit in advanced melanoma and patients with non-small cell lung cancer. However, current PD-L1-blocking antibodies lack intrinsic tumor selectivity. Therefore, efficacy may be reduced resulting from on-target and off-tumor binding to PD-L1-expressing normal cells. This may lead to indiscriminate activation of antigen-experienced T cells, including those implicated in autoimmune-related adverse events. To direct PD-L1 blockade to chondroitin sulfate proteoglycan 4 (CSPG4)-expressing cancers and to reactivate anticancer T cells more selectively, we constructed bispecific antibody PD-L1xCSPG4. CSPG4 is an established target antigen that is selectively overexpressed on malignant melanoma and various other difficult-to-treat cancers. PD-L1xCSPG4 showed enhanced capacity for CSPG4-directed blockade of PD-L1 on cancer cells. Importantly, treatment of mixed cultures containing primary patient-derived CSPG4-expressing melanoma cells and autologous tumor-infiltrating lymphocytes with PD-L1xCSPG4 significantly enhanced activation status, IFN-γ production, and cytolytic activity of anticancer T cells. In conclusion, tumor-directed blockade of PD-L1 by PD-L1xCSPG4 may improve efficacy and safety of PD-1/PD-L1 checkpoint blockade for treatment of melanoma and other CSPG4-overexpressing malignancies.

Targeted human cytolytic fusion proteins at the cutting edge: harnessing the apoptosis-inducing properties of human enzymes for the selective elimination of tumor cells

Patient-specific targeted therapy represents the holy grail of anti-cancer therapeutics, allowing potent tumor depletion without detrimental off-target toxicities. Disease-specific monoclonal antibodies have been employed to bind to oncogenic cell-surface receptors, representing the earliest form of immunotherapy. Targeted drug delivery was first achieved by means of antibody-drug conjugates, which exploit the differential expression of tumor-associated antigens as a guiding mechanism for the specific delivery of chemically-conjugated chemotherapeutic agents to diseased target cells. Biotechnological advances have expanded the repertoire of immunology-based tumor-targeting strategies, also paving the way for the next intuitive step in targeted drug delivery: the construction of recombinant protein drugs consisting of an antibody-based targeting domain genetically fused with a cytotoxic peptide, known as an immunotoxin. However, the most potent protein toxins have typically been derived from bacterial or plant virulence factors and commonly feature both off-target toxicity and immunogenicity in human patients. Further refinement of immunotoxin technology thus led to the replacement of monoclonal antibodies with humanized antibody derivatives, including the substitution of non-human toxic peptides with human cytolytic proteins. Preclinically tested human cytolytic fusion proteins (hCFPs) have proven promising as non-immunogenic combinatory anti-cancer agents, however they still require further enhancement to achieve convincing candidacy as a single-mode therapeutic. To date, a portfolio of highly potent human toxins has been established; ranging from microtubule-associated protein tau (MAP tau), RNases, granzyme B (GrB) and death-associated protein kinase (DAPk). In this review, we discuss the most recent findings on the use of these apoptosis-inducing hCFPs for the treatment of various cancers.

The Significance of Chondroitin Sulfate Proteoglycan 4 (CSPG4) in Human Gliomas

Neuron glial antigen 2 (NG2) is a chondroitin sulphate proteoglycan 4 (CSPG4) that occurs in developing and adult central nervous systems (CNSs) as a marker of oligodendrocyte precursor cells (OPCs) together with platelet-derived growth factor receptor α (PDGFRα). It behaves variably in different pathological conditions, and is possibly involved in the origin and progression of human gliomas. In the latter, NG2/CSPG4 induces cell proliferation and migration, is highly expressed in pericytes, and plays a role in neoangiogenesis. NG2/CSPG4 expression has been demonstrated in oligodendrogliomas, astrocytomas, and glioblastomas (GB), and it correlates with malignancy. In rat tumors transplacentally induced by N-ethyl-N-nitrosourea (ENU), NG2/CSPG4 expression correlates with PDGFRα, Olig2, Sox10, and Nkx2.2, and with new vessel formation. In this review, we attempt to summarize the normal and pathogenic functions of NG2/CSPG4, as well as its potential as a therapeutic target.

Human Granzyme B Based Targeted Cytolytic Fusion Proteins

Cancer immunotherapy aims to selectively target and kill tumor cells whilst limiting the damage to healthy tissues. Controlled delivery of plant, bacterial and human toxins or enzymes has been shown to promote the induction of apoptosis in cancerous cells. The 4th generation of targeted effectors are being designed to be as humanized as possible—a solution to the problem of immunogenicity encountered with existing generations. Granzymes are serine proteases which naturally function in humans as integral cytolytic effectors during the programmed cell death of cancerous and pathogen-infected cells. Secreted predominantly by cytotoxic T lymphocytes and natural killer cells, granzymes function mechanistically by caspase-dependent or caspase-independent pathways. These natural characteristics make granzymes one of the most promising human enzymes for use in the development of fusion protein-based targeted therapeutic strategies for various cancers. In this review, we explore research involving the use of granzymes as cytolytic effectors fused to antibody fragments as selective binding domains.

Chondroitin Sulfate Proteoglycan 4 and Its Potential As an Antibody Immunotherapy Target across Different Tumor Types

Overexpression of the chondroitin sulfate proteoglycan 4 (CSPG4) has been associated with the pathology of multiple types of such as melanoma, breast cancer, squamous cell carcinoma, mesothelioma, neuroblastoma, adult and pediatric sarcomas, and some hematological cancers. CSPG4 has been reported to exhibit a role in the growth and survival as well as in the spreading and metastasis of tumor cells. CSPG4 is overexpressed in several malignant diseases, while it is thought to have restricted and low expression in normal tissues. Thus, CSPG4 has become the target of numerous anticancer treatment approaches, including monoclonal antibody-based therapies. This study reviews key potential anti-CSPG4 antibody and immune-based therapies and examines their direct antiproliferative/metastatic and immune activating mechanisms of action.