Fourth-generation chimeric antigen receptor T cells targeting folate receptor alpha antigen expressed on breast cancer cells for adoptive T cell therapy

CRISPR/Cas9-mediated knockout strategies for enhancing immunotherapy in breast cancer

Breast cancer, a prevalent disease with significant mortality rates, often presents treatment challenges due to its complex genetic makeup. This review explores the potential of combining Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene knockout strategies with immunotherapeutic approaches to enhance breast cancer treatment. The CRISPR/Cas9 system, renowned for its precision in inducing genetic alterations, can target and eliminate specific cancer cells, thereby minimizing off-target effects. Concurrently, immunotherapy, which leverages the immune system's power to combat cancer, has shown promise in treating breast cancer. By integrating these two strategies, we can potentially augment the effectiveness of immunotherapies by knocking out genes that enable cancer cells to evade the immune system. However, safety considerations, such as off-target effects and immune responses, necessitate careful evaluation. Current research endeavors aim to optimize these strategies and ascertain the most effective methods to stimulate the immune response. This review provides novel insights into the integration of CRISPR/Cas9-mediated knockout strategies and immunotherapy, a promising avenue that could revolutionize breast cancer treatment as our understanding of the immune system's interplay with cancer deepens.

Deciphering the landscape of triple negative breast cancer from microenvironment dynamics and molecular insights to biomarker analysis and therapeutic modalities

Triple negative breast cancer (TNBC) displays a notable challenge in clinical oncology due to its invasive nature which is attributed to the absence of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor (HER-2). The heterogenous tumor microenvironment (TME) of TNBC is composed of diverse constituents that intricately interact to evade immune response and facilitate cancer progression and metastasis. Based on molecular gene expression, TNBC is classified into four molecular subtypes: basal-like (BL1 and BL2), luminal androgen receptor (LAR), immunomodulatory (IM), and mesenchymal. TNBC is an aggressive histological variant with adverse prognosis and poor therapeutic response. The lack of response in most of the TNBC patients could be attributed to the heterogeneity of the disease, highlighting the need for more effective treatments and reliable prognostic biomarkers. Targeting certain signaling pathways and their components has emerged as a promising therapeutic strategy for improving patient outcomes. In this review, we have summarized the interactions among various components of the dynamic TME in TNBC and discussed the classification of its molecular subtypes. Moreover, the purpose of this review is to compile and provide an overview of the most recent data about recently discovered novel TNBC biomarkers and targeted therapeutics that have proven successful in treating metastatic TNBC. The emergence of novel therapeutic strategies such as chemoimmunotherapy, chimeric antigen receptor (CAR)-T cells-based immunotherapy, phytometabolites-mediated natural therapy, photodynamic and photothermal approaches have made a significant positive impact and have paved the way for more effective interventions.

Breast cancer immunotherapy using scFv antibody-based approaches, a systematic review

Breast cancer is considered as the most common malignancy in women and the second leading cause of death related to cancer. Recombinant DNA technologies accelerated the development of antibody-based cancer therapy, which is effective in a broad range of cancers. The objective of the present study was to perform a systematic review on breast cancer immunotherapy using single-chain fragment variable (scFv) antibody formats. Searches were performed up to March 2023 using PubMed, Scopus, and Web of Science (ISI) databases. Three reviewers independently assessed study eligibility, data extraction, and evaluated the methodological quality of included primary studies. Different immunotherapy approaches have been identified and the most common approaches were scFv-conjugates, followed by simple scFvs and chimeric antigen receptor (CAR) therapy, respectively. Among breast cancer antigens, HER superfamily, CD family, and EpCAM were applied as the most important breast cancer immunotherapy targets. The present study shed more lights on scFv-based breast cancer immunotherapy approaches.

CAR T cell infiltration and cytotoxic killing within the core of 3D breast cancer spheroids under the control of antigen sensing in microwell arrays

The success of chimeric antigen receptor (CAR) T cells in blood cancers has intensified efforts to develop CAR T therapies for solid cancers. In the solid tumor microenvironment, CAR T cell trafficking and suppression of cytotoxic killing represent limiting factors for therapeutic efficacy. Here, we present a microwell platform to study CAR T cell interactions with 3D breast tumor spheroids and determine predictors of anti-tumor CAR T cell function. To precisely control antigen sensing, we utilized a switchable adaptor CAR system that covalently attaches to co-administered antibody adaptors and mediates antigen recognition. Following the addition of an anti-HER2 adaptor antibody, primary human CAR T cells exhibited higher infiltration, clustering, and secretion of effector cytokines. By tracking CAR T cell killing in individual spheroids, we showed the suppressive effects of spheroid size and identified the initial CAR T cell to spheroid area ratio as a predictor of cytotoxicity. We demonstrate that larger spheroids exhibit higher hypoxia levels and are infiltrated by CAR T cells with a suppressed activation state, characterized by reduced expression of IFN-γ, TNF-α, and granzyme B. Spatiotemporal analysis revealed lower CAR T cell numbers and cytotoxicity in the spheroid core compared to the periphery. Finally, increasing CAR T cell seeding density resulted in higher CAR T cell infiltration and cancer cell elimination in the spheroid core. Our findings provide new quantitative insight into CAR T cell function within 3D cancer spheroids. Given its miniaturized nature and live imaging capabilities, our microfabricated system holds promise for screening cellular immunotherapies.

Immunologic tumor microenvironment modulators for turning cold tumors hot

Tumors can be classified into distinct immunophenotypes based on the presence and arrangement of cytotoxic immune cells within the tumor microenvironment (TME). Hot tumors, characterized by heightened immune activity and responsiveness to immune checkpoint inhibitors (ICIs), stand in stark contrast to cold tumors, which lack immune infiltration and remain resistant to therapy. To overcome immune evasion mechanisms employed by tumor cells, novel immunologic modulators have emerged, particularly ICIs targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1/programmed death-ligand 1(PD-1/PD-L1). These agents disrupt inhibitory signals and reactivate the immune system, transforming cold tumors into hot ones and promoting effective antitumor responses. However, challenges persist, including primary resistance to immunotherapy, autoimmune side effects, and tumor response heterogeneity. Addressing these challenges requires innovative strategies, deeper mechanistic insights, and a combination of immune interventions to enhance the effectiveness of immunotherapies. In the landscape of cancer medicine, where immune cold tumors represent a formidable hurdle, understanding the TME and harnessing its potential to reprogram the immune response is paramount. This review sheds light on current advancements and future directions in the quest for more effective and safer cancer treatment strategies, offering hope for patients with immune-resistant tumors.

CAR T cell infiltration and cytotoxic killing within the core of 3D breast cancer spheroids under control of antigen sensing in microwell arrays

The success of chimeric antigen receptor (CAR) T cells in blood cancers has intensified efforts to develop CAR T therapies for solid cancers. In the solid tumor microenvironment, CAR T cell trafficking and suppression of cytotoxic killing represent limiting factors for therapeutic efficacy. Here, we present a microwell platform to study CAR T cell interactions with 3D tumor spheroids and determine predictors of anti-tumor CAR T cell function. To precisely control antigen sensing by CAR T cells, we utilized a switchable adaptor CAR system, that instead of directly binding to an antigen of interest, covalently attaches to co-administered antibody adaptors that mediate tumor antigen recognition. Following addition of an anti-HER2 adaptor antibody, primary human CAR T cells exhibited higher infiltration and clustering compared to the no adaptor control. By tracking CAR T cell killing at the individual spheroid level, we showed the suppressive effects of spheroid size and identified the initial CAR T cell : spheroid area ratio as a predictor of cytotoxicity. Spatiotemporal analysis revealed lower CAR T cell numbers and cytotoxicity in the spheroid core compared to the periphery. Finally, increasing CAR T cell seeding density, resulted in higher CAR T cell infiltration and cancer cell elimination in the spheroid core. Our findings provide new quantitative insights into CAR T cell-mediated killing of HER2+ breast tumor cells. Given the miniaturized nature and live imaging capabilities, our microfabricated system holds promise for discovering cell-cell interaction mechanisms that orchestrate antitumor CAR T cell functions and screening cellular immunotherapies in 3D tumor models.

Cytotoxicity of fourth-generation anti-Trop2 CAR-T cells against breast cancer

The treatment of breast cancer (BC) remains a formidable challenge due to the emergence of drug resistance, necessitating the exploration of innovative strategies. Chimeric antigen receptor (CAR)-T cell therapy, a groundbreaking approach in hematologic malignancies, is actively under investigation for its potential application in solid tumors, including BC. Trophoblast cell surface antigen 2 (Trop2) has emerged as a promising immunotherapeutic target in various cancers and is notably overexpressed in BC. To enhance therapeutic efficacy in BC, a fourth-generation CAR (CAR4) construct was developed. This CAR4 design incorporates an anti-Trop2 single-chain variable fragment (scFv) fused with three costimulatory domains -CD28/4-1BB/CD27, and CD3ζ. Comparative analysis with the conventional second-generation CAR (CAR2; 28ζ) revealed that anti-Trop2 CAR4 T cells exhibited heightened cytotoxicity and interferon-gamma (IFN-γ) production against Trop2-expressing MCF-7 cells. Notably, anti-Trop2 CAR4-T cells demonstrated superior long-term cytotoxic functionality and proliferative capacity. Crucially, anti-Trop2 CAR4-T cells displayed specific cytotoxicity against Trop2-positive BC cells (MDA-MB-231, HCC70, and MCF-7) in both two-dimensional (2D) and three-dimensional (3D) culture systems. Following antigen-specific killing, these cells markedly secreted interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), IFN-γ, and Granzyme B compared to non-transduced T cells. This study highlights the therapeutic potential of anti-Trop2 CAR4-T cells in adoptive T cell therapy for BC, offering significant promise for the advancement of BC treatment strategies.

The nexus of natural killer cells and melanoma tumor microenvironment: crosstalk, chemotherapeutic potential, and innovative NK cell-based therapeutic strategies

The metastasis of melanoma cells to regional lymph nodes and distant sites is an important contributor to cancer-related morbidity and mortality among patients with melanoma. This intricate process entails dynamic interactions involving tumor cells, cellular constituents, and non-cellular elements within the microenvironment. Moreover, both microenvironmental and systemic factors regulate the metastatic progression. Central to immunosurveillance for tumor cells are natural killer (NK) cells, prominent effectors of the innate immune system with potent antitumor and antimetastatic capabilities. Recognizing their pivotal role, contemporary immunotherapeutic strategies are actively integrating NK cells to combat metastatic tumors. Thus, a meticulous exploration of the interplay between metastatic melanoma and NK cells along the metastatic cascade is important. Given the critical involvement of NK cells within the melanoma tumor microenvironment, this comprehensive review illuminates the intricate relationship between components of the melanoma tumor microenvironment and NK cells, delineating their multifaceted roles. By shedding light on these critical aspects, this review advocates for a deeper understanding of NK cell dynamics within the melanoma context, driving forward transformative strategies to combat this cancer.

Biomarkers and experimental models for cancer immunology investigation

The rapid advancement of tumor immunotherapies poses challenges for the tools used in cancer immunology research, highlighting the need for highly effective biomarkers and reproducible experimental models. Current immunotherapy biomarkers encompass surface protein markers such as PD-L1, genetic features such as microsatellite instability, tumor-infiltrating lymphocytes, and biomarkers in liquid biopsy such as circulating tumor DNAs. Experimental models, ranging from 3D in vitro cultures (spheroids, submerged models, air-liquid interface models, organ-on-a-chips) to advanced 3D bioprinting techniques, have emerged as valuable platforms for cancer immunology investigations and immunotherapy biomarker research. By preserving native immune components or coculturing with exogenous immune cells, these models replicate the tumor microenvironment in vitro. Animal models like syngeneic models, genetically engineered models, and patient-derived xenografts provide opportunities to study in vivo tumor-immune interactions. Humanized animal models further enable the simulation of the human-specific tumor microenvironment. Here, we provide a comprehensive overview of the advantages, limitations, and prospects of different biomarkers and experimental models, specifically focusing on the role of biomarkers in predicting immunotherapy outcomes and the ability of experimental models to replicate the tumor microenvironment. By integrating cutting-edge biomarkers and experimental models, this review serves as a valuable resource for accessing the forefront of cancer immunology investigation.

CAR-T cell therapy for hematological malignancies: History, status and promise

For many years, the methods of cancer treatment are usually surgery, chemotherapy and radiation therapy. Although these methods help to improve the condition, most tumors still have a poor prognosis. In recent years, immunotherapy has great potential in tumor treatment. Chimeric antigen receptor T-cell immunotherapy (CAR-T) uses the patient's own T cells to express chimeric antigen receptors. Chimeric antigen receptor (CAR) recognizes tumor-associated antigens and kills tumor cells. CAR-T has achieved good results in the treatment of hematological tumors. In 2017, the FDA approved the first CAR-T for the treatment of B-cell acute lymphoblastic leukemia (ALL). In October of the same year, the FDA approved CAR-T to treat B-cell lymphoma. In order to improve and enhance the therapeutic effect, CAR-T has become a research focus in recent years. The structure of CAR, the targets of CAR-T treatment, adverse reactions and improvement measures during the treatment process are summarized. This review is an attempt to highlight recent and possibly forgotten findings of advances in chimeric antigen receptor T cell for treatment of hematological tumors.

Anti-PD-L1 × anti-CD3 bispecific T-cell engager-armed T cells can overcome immunosuppression and redirect T cells to kill breast cancer cells expressing PD-L1

T cell-based immunotherapy has transformed cancer treatment. Nonetheless, T cell antitumor activity can be inhibited by an immune checkpoint molecule expressed on cancer cells, program death ligand 1 (PD-L1), which interacts with the PD-1 on T cells. We generated αPD-L1 × αCD3 bispecific T-cell engager-armed T cells (BATs) to prevent PD-L1/PD-1 interaction and hence to redirect T cells to kill cancer cells. αPD-L1 × αCD3 bispecific T-cell engagers (BTEs) were produced from Chinese hamster ovary (CHO) cells to arm human primary T cells. Flow cytometry was used to investigate BTE binding to BATs. The cytotoxicity of BATs against PD-L1-expressing breast cancer (BC) cell lines was assessed in 2-dimensional (2D) and 3-dimensional (3D) culture models. The binding stability of BTE on BATs and their efficacy after cryopreservation were also examined. The CHO cell BTE expression yield was 3.34 mg/ml. The binding ability on T cells reached 91.02 ± 4.2 %. BATs specifically lysed PD-L1-expressing BC cells, with 56.4 ± 15.3 % HCC70 cells and 70.67 ± 15.6 % MDA-MB-231 cells lysed at a 10:1 effector-to-target ratio. BATs showed slight, nonsignificant lysis of PD-L1-negative BC cells, MCF-7, and T47D. Moreover, BATs significantly disrupted MDA-MB-231 3D spheroids expressing PD-L1 after 48 and 72 h of coculture. Cryopreserved BATs maintained BTE binding stability, cell viability, and anticancer activity, comparable to fresh BATs. αPD-L1 × αCD3 BATs induced the cytolysis of PD-L1-expressing BC cells in 2D and 3D coculture assays. BATs can be prepared and preserved, facilitating their use and transportation. This study demonstrates the potential of αPD-L1 × αCD3 BATs in treating cancers with positive PD-L1 expression.

Enhancement of PD-L1-attenuated CAR-T cell function through breast cancer-associated fibroblasts-derived IL-6 signaling via STAT3/AKT pathways

BACKGROUND

Carcinoma-associated fibroblasts (CAFs) play a critical role in cancer progression and immune cell modulation. In this study, it was aimed to evaluate the roles of CAFs-derived IL-6 in doxorubicin (Dox) resistance and PD-L1-mediated chimeric antigenic receptor (CAR)-T cell resistance in breast cancer (BCA).

METHODS

CAF conditioned-media (CM) were collected, and the IL-6 level was measured by ELISA. CAF-CM were treated in MDA-MB-231 and HCC70 TNBC cell lines and siIL-6 receptor (IL-6R) knocked down (KD) cells to determine the effect of CAF-derived IL-6 on Dox resistance by flow cytometry and on increased PD-L1 through STAT3, AKT and ERK1/2 pathways by Western blot analysis. After pre-treating with CM, the folate receptor alpha (FRα)-CAR T cell cytotoxicity was evaluated in 2D and 3D spheroid culture assays.

RESULTS

The results showed a significant level of IL-6 in CAF-CM compared to that of normal fibroblasts (NFs). The CM with high IL-6 level significantly induced Dox resistance; and PD-L1 expression through STAT3 and AKT pathways in MDA-MB-231 and HCC70 cells. These induction effects were attenuated in siIL-6R KD cells. Moreover, the TNBC cell lines that were CM-treated with STAT3 and an AKT inhibitor had a reduced effect of IL-6 on PD-L1 expression. BCA cells with high IL-6 containing-CM treatment had resistance to cancer cell killing by FRα CAR-T cells compared to untreated cells.

CONCLUSION

These results highlight CAF-derived IL-6 in the resistance of chemotherapy and T cell therapy. Using inhibitors of IL6-STAT3/AKT-PD-L1 axis may provide a potential benefit of Dox and CAR-T cell therapies in BCA patients.

Fine-Tuning through Generations: Advances in Structure and Production of CAR-T Therapy

Chimeric antigen receptor (CAR)-T cell therapy is a promising form of immunotherapy that has seen significant advancements in the past few decades. It involves genetically modifying T cells to target cancer cells expressing specific antigens, providing a novel approach to treating various types of cancer. However, the initial success of first-generation CAR-T cells was limited due to inadequate proliferation and undesirable outcomes. Nonetheless, significant progress has been made in CAR-T cell engineering, leading to the development of the latest fifth-generation CAR-T cells that can target multiple antigens and overcome individual limitations. Despite these advancements, some shortcomings prevent the widespread use of CAR-T therapy, including life-threatening toxicities, T-cell exhaustion, and inadequate infiltration for solid tumors. Researchers have made considerable efforts to address these issues by developing new strategies for improving CAR-T cell function and reducing toxicities. This review provides an overview of the path of CAR-T cell development and highlights some of the prominent advances in its structure and manufacturing process, which include the strategies to improve antigen recognition, enhance T-cell activation and persistence, and overcome immune escape. Finally, the review briefly covers other immune cells for cancer therapy and ends with the discussion on the broad prospects of CAR-T in the treatment of various diseases, not just hematological tumors, and the challenges that need to be addressed for the widespread clinical application of CAR-T cell therapies.

Emerging Targeted Therapies for HER2-Positive Breast Cancer

Breast cancer is the most common cancer in women and the leading cause of death. HER2 overexpression is found in approximately 20% of breast cancers and is associated with a poor prognosis and a shorter overall survival. Tratuzumab, a monoclonal antibody directed against the HER2 receptor, is the standard of care treatment. However, a third of the patients do not respond to therapy. Given the high rate of resistance, other HER2-targeted strategies have been developed, including monoclonal antibodies such as pertuzumab and margetuximab, trastuzumab-based antibody drug conjugates such as trastuzumab-emtansine (T-DM1) and trastuzumab-deruxtecan (T-DXd), and tyrosine kinase inhibitors like lapatinib and tucatinib, among others. Moreover, T-DXd has proven to be of use in the HER2-low subtype, which suggests that other HER2-targeted therapies could be successful in this recently defined new breast cancer subclassification. When patients progress to multiple strategies, there are several HER2-targeted therapies available; however, treatment options are limited, and the potential combination with other drugs, immune checkpoint inhibitors, CAR-T cells, CAR-NK, CAR-M, and vaccines is an interesting and appealing field that is still in development. In this review, we will discuss the highlights and pitfalls of the different HER2-targeted therapies and potential combinations to overcome metastatic disease and resistance to therapy.

Molecular dynamics insight of interaction between the functionalized-carbon nanotube and cancerous cell membrane in doxorubicin delivery

BACKGROUND AND OBJECTIVE

Doxorubicin (DOX) is a known anticancer drug which is widely used in cancer therapy. Carbon nanotubes (CNTs) are among the most promising platforms for smart drug delivery applications. However, due to the toxicity and their low sulubility their application is limited and their functionalization with wide range of biomolecules are suggested. Therefore, the functionalized carbon nanotubes (f-CNT) with carboxyl (CNT-COO) and folic acid (CNT-COO-FA) were investigated as drug-carrier.

METHODS

Molecular dynamics (MD) simulation along with the Density Functional Theory (DFT) methods are being used to study the drug loading process on functionalized carbon nanotubes.

RESULTS

The results indicate that doxorubicin molecules interact more with CNT-COO-FA than CNT-COO. The embedded dipalmitoylphosphatidylcholine (DPPC) lipid bilayer with a folate receptor was considered a cancerous cell's representative model. Then the drug release from the f-CNTs near the lipid bilayer was simulated. The results showed that CNT-COO-FA with a pH and ligand-sensitive mechanism strongly interacts with cancerous cells, which led to higher drug release, in agreement with the experimental results. The conformational changes of the lipid bilayer and folate receptor during drug release were evaluated. The analysis showed that drug release from CNT-COO-FA has significantly changed lipid bilayer and receptor conformations. The obtained results were interpreted and justified by considering the molecular mechanisms which control the drug delivery in the studied systems.

CONCLUSIONS

Based on the obtained results, CNT-COO-FA has a better performance during the drug release compared to CNT-COO in delivering doxorubicin. Both pH and ligand sensitive mechanisms are found to be responsible for higher drug delivery efficiency of CNT-COO-FA. In contrast, CNT-COO can only enhance drug delivery efficiently with a pH-sensitive mechanism.

Chimeric Antigen Receptor T-Cell Therapy for Solid Tumors: The Past and the Future

Chimeric antigen receptor (CAR) T-cell therapy is the new standard treatment for various indications in patients with advanced hematologic malignancies. Despite the several preclinical and early phase clinical trials, the overall clinical experience has been disappointing when applying this innovative therapy in solid tumors. The failure of CAR T-cell therapy and its limited antitumor activity in solid tumors have been attributed to several mechanisms, including tumor antigen heterogeneity, the hostile tumor microenvironment and poor trafficking of CAR T cells into tumor sites, and the unacceptable toxicities in some settings, among others. However, remarkable improvements have been made in understanding many of these failure mechanisms for which several emerging novel approaches are being applied to overcome these challenges. In this review, after a brief historic background for immunotherapy in solid tumors, we highlight the recent developments achieved in CAR T-cell designs, summarize completed clinical trials, and discuss current challenges facing CAR T-cell therapy and the suggested strategies to overcome these barriers.

The challenge of selecting tumor antigens for chimeric antigen receptor T-cell therapy in ovarian cancer

Ovarian cancer (OC) is one of the most common cancers in women, with a high mortality rate and very few available and effective treatments. Evidence shows that immunotherapy in OC has not been very successful because immune checkpoint blockers have not achieved satisfactory clinical outcomes. On the other hand, as one of the effective treatment approaches, chimeric antigen receptor T-cell (CAR T-cell) therapy has gained a moral position, especially in blood malignancies. Although in solid tumors, CAR T-cell therapy faces various complications and challenges. One of these challenges is selecting the appropriate tumor antigen targeted by CAR T cells, making the selection difficult due to the expression of antigens by tumor cells and normal cells. In addition, the rate of tumor antigen expression and CAR T-cell access to the desired antigen and proper stimulation of CAR T cells can be other important points in antigen selection. This review summarized common tumor antigens and the challenges of selecting them in CAR T cells therapy of OC.

Immunotherapy and immunoengineering for breast cancer; a comprehensive insight into CAR-T cell therapy advancements, challenges and prospects

BACKGROUND

Breast cancer (BC) is a highly prevalent solid cancer with a high-rise infiltration of immune cells, turning it into a significant candidate for tumor-specific immunotherapies. Chimeric antigen receptor (CAR)-T cells are emerging as immunotherapeutic tools with genetically engineered receptors to efficiently recognize and attack tumor cells that express specific target antigens. Technological advancements in CAR design have provided five generations of CAR-T cells applicable to a wide range of cancer patients while boosting CAR-T cell therapy safety. However, CAR-T cell therapy is ineffective against breast cancer because of the loss of specified antigens, the immunosuppressive nature of the tumor and CAR-T cell-induced toxicities. Next-generation CAR-T cells actively pass through the tumor vascular barriers, persist for extended periods and disrupt the tumor microenvironment (TME) to block immune escape.

CONCLUSION

CAR-T cell therapy embodies advanced immunotherapy for BC, but further pre-clinical and clinical assessments are recommended to achieve maximized efficiency and safety.

Potential of chimeric antigen receptor (CAR)-redirected immune cells in breast cancer therapies: Recent advances

Despite substantial developments in conventional treatments such as surgery, chemotherapy, radiotherapy, endocrine therapy, and molecular-targeted therapy, breast cancer remains the leading cause of cancer mortality in women. Currently, chimeric antigen receptor (CAR)-redirected immune cell therapy has emerged as an innovative immunotherapeutic approach to ameliorate survival rates of breast cancer patients by eliciting cytotoxic activity against cognate tumour-associated antigens expressing tumour cells. As a crucial component of adaptive immunity, T cells and NK cells, as the central innate immune cells, are two types of pivotal candidates for CAR engineering in treating solid malignancies. However, the biological distinctions between NK cells- and T cells lead to differences in cancer immunotherapy outcomes. Likewise, optimal breast cancer removal via CAR-redirected immune cells requires detecting safe target antigens, improving CAR structure for ideal immune cell functions, promoting CAR-redirected immune cells filtration to the tumour microenvironment (TME), and increasing the ability of these engineered cells to persist and retain within the immunosuppressive TME. This review provides a concise overview of breast cancer pathogenesis and its hostile TME. We focus on the CAR-T and CAR-NK cells and discuss their significant differences. Finally, we deliver a summary based on recent advancements in the therapeutic capability of CAR-T and CAR-NK cells in treating breast cancer.

The landscape of chimeric antigen receptor T cell therapy in breast cancer: Perspectives and outlook

Chimeric antigen receptor-T (CAR-T) cell therapy is a revolutionary adoptive cell therapy, which could modify and redirect T cells to specific tumor cells. Since CAR-T cell therapy was first approved for B cell-derived malignancies in 2017, it has yielded unprecedented progress in hematological tumors and has dramatically reshaped the landscape of cancer therapy in recent years. Currently, cumulative evidence has demonstrated that CAR-T cell therapy could be a viable therapeutic strategy for solid cancers. However, owing to the immunosuppressive tumor microenvironment (TME) and heterogenous tumor antigens, the application of CAR-T cell therapy against solid cancers requires circumventing more challenging obstacles. Breast cancer is characterized by a high degree of invasiveness, malignancy, and poor prognosis. The review highlights the underlying targets of CAR-T cell therapy in breast cancer, summarizes the challenges associated with CAR-T cell therapy, and proposes the strategies to overcome these challenges, which provides a novel approach to breast cancer treatment.

Activation of cytotoxic T lymphocytes by self-differentiated myeloid-derived dendritic cells for killing breast cancer cells expressing folate receptor alpha protein

Adoptive cell transfer (ACT) is a promising approach for cancer treatment. Activation of T lymphocytes by self-differentiated myeloid-derived antigen-presenting-cells reactive against tumor (SmartDC) resulted in specific anti-cancer function. Folate receptor alpha (FRα) is highly expressed in breast cancer (BC) cells and thus potential to be a target antigen for ACT. To explore the SmartDC technology for treatment of BC, we create SmartDC expressing FRα antigen (SmartDC-FRα) for activation of FRα-specific T lymphocytes. Human primary monocytes were transduced with lentiviruses containing tri-cistronic complementary DNA sequences encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4), and FRα to generate SmartDC-FRα. Autologous T lymphocytes were activated by SmartDC-FRα by coculture. The activated T lymphocytes exhibited enhanced cytotoxicity against FRα-expressing BC cell cultures. Up to 84.9 ± 6.2% of MDA-MB-231 and 89.7 ± 1.9% of MCF-7 BC cell lines were specifically lysed at an effector-to-target ratio of 20:1. The cytotoxicity of T lymphocytes activated by SmartDC-FRα was also demonstrated in three-dimensional (3D) spheroid culture of FRα-expressing BC cells marked by size reduction and spheroid disruption. This study thus portray the potential development of T lymphocytes activated by SmartDC-FRα as ACT in FRα-expressing BC treatment.

Different Serum, Different Protein Corona! The Impact of the Serum Source on Cellular Targeting of Folic Acid-Modified Chitosan-Based Nanoparticles

The nanoparticle (NP) protein corona represents an interface between biological components and NPs, dictating their cellular interaction and biological fate. To assess the success of cellular targeting, NPs modified with targeting ligands are incubated with target cells in serum-free culture medium or in the presence of fetal bovine serum (FBS). In the former, the role of the corona is overlooked, and in the latter, the effects of a corona that does not represent the one forming in humans nor the respective disease state are considered. Via proteomic analysis, we demonstrate how the difference in the composition of FBS, sera from healthy human volunteers, and breast cancer patients (BrCr Pt) results in the formation of completely different protein coronas around the same NP. Successful in vitro targeting of breast cancer cells was only observed when NPs were incubated with target cells in the presence of BrCr Pt sera only. In such cases, the success of targeting was not attributed to the targeting ligand itself, but to the adsorption of specific serum proteins that facilitate NP uptake by cancer cells in the presence of BrCr Pt sera. This work therefore demonstrates how the serum source affects the reliability of in vitro experiments assessing NP-cell interactions and the consequent success or failure of active targeting and may in fact indicate an additional reason for the limited clinical success of drug targeting by NPs in cancer.

Adoptive Cellular Therapy for Multiple Myeloma Using CAR- and TCR-Transgenic T Cells: Response and Resistance

Despite the substantial improvement of therapeutic approaches, multiple myeloma (MM) remains mostly incurable. However, immunotherapeutic and especially T cell-based approaches pioneered the therapeutic landscape for relapsed and refractory disease recently. Targeting B-cell maturation antigen (BCMA) on myeloma cells has been demonstrated to be highly effective not only by antibody-derived constructs but also by adoptive cellular therapies. Chimeric antigen receptor (CAR)-transgenic T cells lead to deep, albeit mostly not durable responses with manageable side-effects in intensively pretreated patients. The spectrum of adoptive T cell-transfer covers synthetic CARs with diverse specificities as well as currently less well-established T cell receptor (TCR)-based personalized strategies. In this review, we want to focus on treatment characteristics including efficacy and safety of CAR- and TCR-transgenic T cells in MM as well as the future potential these novel therapies may have. ACT with transgenic T cells has only entered clinical trials and various engineering strategies for optimization of T cell responses are necessary to overcome therapy resistance mechanisms. We want to outline the current success in engineering CAR- and TCR-T cells, but also discuss challenges including resistance mechanisms of MM for evading T cell therapy and point out possible novel strategies.

Development of a Novel Anti-CD19 CAR Containing a Fully Human scFv and Three Costimulatory Domains

Second-generation anti-CD19-chimeric antigen receptor T cells (anti-CD19-CAR2 T cells) are effective for treating B-cell malignancies; however, anti-CD19-CAR2 T cells can induce human anti-mouse immune responses because anti-CD19 single-chain variable fragment (scFv) in the CAR molecules is derived from a murine FMC63 (mFMC63) monoclonal antibody. Consequently, the persistence of mFMC63-CAR2 T cells and their therapeutic efficiency in patients are decreased, which results in tumor relapse. In an attempt to remedy this shortcoming, we generated a new anti-CD19-CAR T cells containing fully human anti-CD19 scFv (Hu1E7-CAR4 T cells) to pre-clinically evaluate and compare with mFMC63-CAR4 T cells. The human anti-CD19 scFv (Hu1E7) was isolated from a human scFv phage display library and fused to the hinge region of CD8α, the transmembrane domain of CD28, three intracellular costimulatory domains (CD28, 4-1BB, and CD27), and a CD3ζ signaling domain (28BB27ζ). Compared to mFMC63-CAR2 T cells (BBζ) and mFMC63-CAR3 (BB27ζ), the mFMC63-CAR4 T cells (28BB27ζ) exerted superior anti-tumor activity against Raji (CD19⁺) target cell. The Hu1E7-CAR4 and mFMC63-CAR4 T cells demonstrated comparable cytotoxicity and proliferation. Interestingly, compared to mFMC63-CAR4 T cells, the Hu1E7-CAR4 T cells secreted lower levels of cytokines (IFN-γ and TNF-α), which may be due to the lower binding affinity of Hu1E7-CAR4 T cells. These findings demonstrated the successfulness in creation of a new CAR T cells containing a novel fully human-derived scFv specific to CD19⁺ cancer cells. In vivo studies are needed to further compare the anti-tumor efficacy and safety of Hu1E7-CAR4 T cells and mFMC63-CAR4 T cells.

The other side to the use of active targeting ligands; the case of folic acid in the targeting of breast cancer

Due to its overexpression in cancer cells, the folate receptor (FR) is heavily exploited in the active targeting of nanoparticles (NPs). Its ligand, folic acid (FA) is as a consequence widely used as a NP targeting ligand. Although rather popular and successful in principle, recent data has shown that FA may result in breast cancer initiation and progression, which questions the suitability of FA as NP cancer targeting ligand. In this work, intravenous administration of free FA to healthy female mice resulted in breast tissue dysplasia, hyperplasia and in the increased expression of human epidermal growth factor receptor-2 (HER2), folate receptor (FR), cancer antigen 15-3 (CA15.3), vascular endothelial growth factor (VEGF), signal transducer and activator of transcription 3 (STAT3) and the pro-inflammatory cytokines, tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6) and interleukin-1β. In addition to the reduction in IL2. To evaluate the suitability and safety of FA as NP targeting ligand in breast cancer, small (≈ 150 nm) and large (≈ 500 nm) chitosan NPs were formulated and decorated with two densities of FA. The success of active targeting by FA was confirmed in two breast cancer cell lines (MCF-7 and MDA-MB-231 cells) in comparison to HEK293 cells. FA modified NPs that demonstrated successful active targeting in-vitro were assessed in-vivo. Upon intravenous administration, large NPs modified with a high density of FA accumulated in the breast tissue and resulted in similar effects as those observed with free FA. These results therefore question the suitability of FA as a targeting ligand in breast cancer and shed light on the importance of considering the activity (other than targeting) of the ligands used in NP active targeting.

Current progress in chimeric antigen receptor T cell therapy for glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the deadliest brain tumors with an unfavorable prognosis and overall survival of approximately 20 months following diagnosis. The current treatment for GBM includes surgical resections and chemo‐ and radiotherapeutic modalities, which are not effective. CAR‐T immunotherapy has been proven effective for CD19‐positive blood malignancies, and the application of CAR‐T cell therapy for solid tumors including GBM offers great hope for this aggressive tumor which has a limited response to current treatments. CAR‐T technology depends on the use of patient‐specific T cells genetically engineered to express specific tumor‐associated antigens (TAAs). Interaction of CAR‐T cells with tumor cells triggers the destruction/elimination of these cells by the induction of cytotoxicity and the release of different cytokines. Despite the great promise of CAR‐T cell‐based therapy several challenges exist. These include the heterogeneity of GBM cancer cells, aberrant various signaling pathways involved in tumor progression, antigen escape, the hostile inhibitory GBM microenvironment, T cell dysfunction, blood‐brain barrier, and defective antigen presentation. All need to be addressed before full application at the clinical level can begin. Herein we provide a focused review of the rationale for the use of different types of CAR‐T cells (including FcγRs), the different GBM‐associated antigens, the challenges still facing CAR‐T‐based therapy, and means to overcome such challenges. Finally, we enumerate currently completed and ongoing clinical trials, highlighting the different ways such trials are designed to overcome specific problems. Exploitation of the full potential of CAR‐T cell therapy for GBM depends on their solution.

Highly Sensitive Electrochemical Biosensor Using Folic Acid-Modified Reduced Graphene Oxide for the Detection of Cancer Biomarker

The detection of cancer biomarkers in the early stages could prevent cancer-related deaths significantly. Nanomaterials combined with biomolecules are extensively used in drug delivery, imaging, and sensing applications by targeting the overexpressed cancer proteins such as folate receptors (FRs) to control the disease by providing earlier treatments. In this investigation, biocompatible reduced graphene oxide (rGO) nanosheets combined with folic acid (FA)-a vitamin with high bioaffinity to FRs-is utilized to develop an electrochemical sensor for cancer detection. To mimic the cancer cell environment, FR-β protein is used to evaluate the response of the rGO-FA sensor. The formation of the rGO-FA nanocomposite was confirmed through various characterization techniques. A glassy carbon (GC) electrode was then modified with the obtained rGO-FA and analyzed via differential pulse voltammetry (DPV) for its specific detection towards FRs. Using the DPV technique, the rGO-FA-modified electrode exhibited a limit of detection (LOD) of 1.69 pM, determined in a linear concentration range from 6 to 100 pM. This excellent electrochemical performance towards FRs detection could provide a significant contribution towards future cancer diagnosis. Moreover, the rGO-FA sensing platform also showed excellent specificity and reliability when tested against similar interfering biomolecules. This rGO-FA sensor offers a great promise to the future medical industry through its highly sensitive detection towards FRs in a fast, reliable, and economical way.

Anti-mucin 1 chimeric antigen receptor T cells for adoptive T cell therapy of cholangiocarcinoma

Current treatments for cholangiocarcinoma (CCA) are largely unsuccessful due to late diagnosis at advanced stage, leading to high mortality rate. Consequently, improved therapeutic approaches are urgently needed. Chimeric antigen receptor (CAR) T cell therapy is a newly potential therapy that can recognize specific surface antigen without major histocompatibility complex (MHC) restriction. Mucin 1 (MUC1) is an attractive candidate antigen as it is highly expressed and associated with poor prognosis and survival in CCA. We, therefore, set forth to create the fourth-generation CAR (CAR4) construct containing anti-MUC1-single-chain variable fragment (scFv) and three co-stimulatory domains (CD28, CD137, and CD27) linked to CD3ζ and evaluate anti-MUC1-CAR4 T cells in CCA models. Compared to untransduced T cells, anti-MUC1-CAR4 T cells produced increased levels of TNF-α, IFN-γ and granzyme B when exposed to MUC1-expressing KKU-100 and KKU-213A CCA cells (all p < 0.05). Anti-MUC1-CAR4 T cells demonstrated specific killing activity against KKU-100 (45.88 ± 7.45%, p < 0.05) and KKU-213A cells (66.03 ± 3.14%, p < 0.001) at an effector to target ratio of 5:1, but demonstrated negligible cytolytic activity against immortal cholangiocytes. Furthermore, the anti-MUC1-CAR4 T cells could effectively disrupt KKU-213A spheroids. These activities of anti-MUC1-CAR4 T cells supports the development of this approach as an adoptive T cell therapeutic strategy for CCA.