Convection-enhanced delivery of nanoencapsulated gene locoregionally yielding ErbB2/Her2-specific CAR-macrophages for brainstem glioma immunotherapy

Injectable oxidized high-amylose starch hydrogel scaffold for macrophage-mediated glioblastoma therapy

Glioblastoma, characterized by rapid proliferation and invasiveness, is largely resistant to current treatment modalities. A major obstacle is the blood-brain barrier (BBB), which restricts the delivery of therapeutic agents as well as the infiltration of effective immune cells into glioblastoma. In this study, we developed an injectable oxidized high-amylose starch hydrogel (OHASM) to serve as a biomaterial scaffold for the delivery of macrophages and macrophage-polarizing drugs, aiming to bypass the BBB and enhance glioblastoma treatment. The in vitro and in vivo experiments confirmed the efficacy of the hydrogel in loading and delivering macrophages and polarizing drugs against glioblastoma. Additionally, the hydrogel's interconnected porous structure was conducive to cellular growth and activity, and its slow release of therapeutics contributed to the extended survival of treated mice in a mouse GL261 glioblastoma tumor model. The immunological mechanisms underlying the therapeutic efficacy were further elucidated, revealing the potential of the hydrogel system to modulate macrophage polarization and induce apoptosis in tumor cells via the poly ADP-ribose polymerase (PARP) pathway. The study underscores the potential of the hydrogel-based macrophage delivery strategy as an effective and safe treatment for glioblastoma, offering a promising avenue for clinical management of this aggressive brain cancer.

In vivo CAR engineering for immunotherapy

Chimeric antigen receptor (CAR)-engineered immune cell therapy represents an important advance in cancer treatments. However, the complex ex vivo cell manufacturing process and stringent patient selection criteria curtail its widespread use. In vivo CAR engineering is emerging as a promising off-the-shelf therapy, providing advantages such as streamlined production, elimination of patient-specific manufacturing, reduced costs and simplified logistics. A large set of preclinical findings has inspired further investigation into treatments for hard-to-treat diseases such as solid tumours and has facilitated the development of advanced products to enhance in vivo CAR engineering efficacy, the persistence of the cellular therapeutic and safety. In this Review, we summarize current in vivo CAR engineering strategies, including nanoparticle-based and viral delivery systems as well as bioinstructive implantable scaffolds, and discuss their advantages and disadvantages. Additionally, we provide a systematic comparison between in vivo and conventional ex vivo CAR engineering methods and address the challenges and future prospects of in vivo CAR engineering.

Overcoming immunotherapy resistance in glioblastoma: challenges and emerging strategies

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults, characterized by rapid proliferation, extensive infiltration, and significant intratumoral heterogeneity. Despite advancements in conventional treatments, including surgery, radiotherapy, and chemotherapy, the prognosis for GBM patients remains poor, with a median survival of approximately 15 months. Immunotherapy has emerged as a promising alternative; however, the unique biological and immunological features, including its immunosuppressive tumor microenvironment (TME) and low mutational burden, render it resistant to many immunotherapeutic strategies. This review explores the key challenges in GBM immunotherapy, focusing on immune evasion mechanisms, the blood-brain barrier (BBB), and the TME. Immune checkpoint inhibitors and CAR-T cells have shown promise in preclinical models but have limited clinical success due to antigen heterogeneity, immune cell exhaustion, and impaired trafficking across the BBB. Emerging strategies, including dual-targeting CAR-T cells, engineered immune cells secreting therapeutic molecules, and advanced delivery systems to overcome the BBB, show potential for enhancing treatment efficacy. Addressing these challenges is crucial for improving GBM immunotherapy outcomes.

Are monocytes a preferable option to develop myeloid cell-based therapies for solid tumors?

In the last two decades, novel and promising cell-based therapies have populated the treatment landscape for haematological tumors. However, commonly exploited T and NK cell-based therapies show limited applicability to solid tumors. This is mainly given by the impaired tumor trafficking capability and limited effector activity of these cells within a highly immunosuppressive tumor microenvironment. Myeloid cells spontaneously home to tumors and can thus be reprogrammed and/or engineered to directly attack tumor cells or locally and selectively deliver therapeutically relevant payloads that may improve the efficacy of immunotherapy against difficult-to-access solid tumors. In the context of myeloid cell-based therapies, adoptive transfer of monocytes has often been overshadowed by infusion of differentiated macrophages or hematopoietic stem cell transplantation despite their promising therapeutic potential. Here, we summarize the recent improvements and benefits of using monocytes for the treatment of solid tumors, their current clinical applications and the challenges of their use as well as some possible strategies to overcome them.

Tissue macrophages: origin, heterogenity, biological functions, diseases and therapeutic targets

Macrophages are immune cells belonging to the mononuclear phagocyte system. They play crucial roles in immune defense, surveillance, and homeostasis. This review systematically discusses the types of hematopoietic progenitors that give rise to macrophages, including primitive hematopoietic progenitors, erythro-myeloid progenitors, and hematopoietic stem cells. These progenitors have distinct genetic backgrounds and developmental processes. Accordingly, macrophages exhibit complex and diverse functions in the body, including phagocytosis and clearance of cellular debris, antigen presentation, and immune response, regulation of inflammation and cytokine production, tissue remodeling and repair, and multi-level regulatory signaling pathways/crosstalk involved in homeostasis and physiology. Besides, tumor-associated macrophages are a key component of the TME, exhibiting both anti-tumor and pro-tumor properties. Furthermore, the functional status of macrophages is closely linked to the development of various diseases, including cancer, autoimmune disorders, cardiovascular disease, neurodegenerative diseases, metabolic conditions, and trauma. Targeting macrophages has emerged as a promising therapeutic strategy in these contexts. Clinical trials of macrophage-based targeted drugs, macrophage-based immunotherapies, and nanoparticle-based therapy were comprehensively summarized. Potential challenges and future directions in targeting macrophages have also been discussed. Overall, our review highlights the significance of this versatile immune cell in human health and disease, which is expected to inform future research and clinical practice.

Exploring the potential of CAR-macrophage therapy

Chimeric antigen receptor T cell (CAR-T) cell therapy has achieved significant success in treating hematologic malignancies, but its efficacy in solid tumor treatment is relatively limited. Therefore, researchers are exploring other genetically modified immune cells as potential treatment strategies to address the challenges in solid tumor therapy. Chimeric antigen receptor macrophage (CAR-M) involves the genetic engineering of macrophages to express chimeric antigen receptors, enabling them to recognize and attack tumor cells. In contrast to CAR-T cells, CAR-M cells offer distinct advantages such as enhanced infiltration and survival capabilities, along with a diverse array of anti-tumor mechanisms, making them a promising immunotherapy approach that may yield better results in solid tumor treatment. This article provides an overview of the research advancements in CAR-M-mediated tumor immunotherapy, encompassing topics such as the design and transduction of CAR, cell sources, anti-tumor mechanisms and clinical applications. The future research direction in this field will involve leveraging innovative biological technologies to augment the anti-tumor efficacy of CAR-M, understand the underlying mechanisms, and enhance the safety and efficacy of CAR-M therapy.

Chimeric antigen receptor-macrophages: Emerging next-generation cell therapy for brain cancer

Adoptive cell-based therapy utilizing chimeric antigen receptor (CAR)-T technology holds promise in the field of neuro-oncology. Significant progress has been made in enhancing both the efficacy and safety of CAR-T-cell therapies. However, challenges such as the multifaceted immunosuppressive impact of the tumor microenvironment and insufficient CAR-T-cell infiltration into brain tumor sites remain a major hurdles. Emerging novel approaches utilizing CAR-macrophages (CAR-MACs) show potent results for brain tumor immunotherapy. CAR-MACs localize to tumor sites more readily, increase immune cell infiltrates, and demonstrate high antitumor efficacy by effectively eliminating tumor cells through mechanisms such as phagocytosis or efferocytosis. This review discusses the current advancements in CAR-MAC cell therapies for brain cancer, followed by an overview of research on manufacturing CAR-MACs for clinical application. We further highlight the potential future applications of CAR-MACs in combinatory therapies in the treatment of brain tumors.

Nanoparticle-mediated universal CAR-T therapy

In recent years, chimeric antigen receptor (CAR)-T cell therapy has been highly successful in treating hematological malignancies, leading to significant advancements in the cancer immunotherapy field. However, the typical CAR-T therapy necessitates the enrichment of patients' own leukocytes for ex vivo production of CAR-T cells, this customized pattern requires a complicated and time-consuming manufacturing procedure, making it costly and less accessible. The off-the-shelf universal CAR-T strategy could reduce manufacturing costs and realize timely drug administration, presenting as an ideal substitute for typical CAR-T therapy. Utilizing nanocarriers for targeted gene delivery is one of the approaches for the realization of universal CAR-T therapy, as biocompatible and versatile nanoparticles could deliver CAR genes to generate CAR-T cells in vivo. Nanoparticle-mediated in situ generation of CAR-T cells possesses multiple advantages, including lowered cost, simplified manufacturing procedure, and shortened administration time, this strategy is anticipated to provide a potentially cost-effective alternative to current autologous CAR-T cell manufacturing, thus facilitating the prevalence and improvement of CAR-T therapy.

Glioblastoma-associated macrophages: A key target in overcoming glioblastoma therapeutic resistance

Glioblastoma multiforme (GBM) is recognized as the most aggressive and malignant form of brain cancer, characterized by a highly heterogeneous phenotype, poor prognosis, and a median survival time of less than 16 months. Recent studies have highlighted the critical role of glioblastoma-associated macrophages (GAMs) in promoting tumor progression and resistance not only to immunotherapy but also to radiotherapy and chemotherapy. GAMs actively suppress immune responses, promote angiogenesis, facilitate tumor metastasis, and induce therapy resistance, through various mechanisms such as cytokines production, signaling pathways regulation, and angiogenesis. In this context, understanding these regulatory mechanisms is essential for developing efficient therapies. Preclinical studies have investigated diverse approaches to target these cells, both as monotherapies or in combination with other treatments. While these approaches have shown promise in strengthening antitumor immune responses in animal models, their clinical success remains to be fully determined. Herein, we provide a comprehensive overview of GAMs's role in GBM therapeutic resistance and summarizes existing approaches to target GAMs in overcoming tumor resistance.

Immunotherapy for leptomeningeal disease from solid tumors: current clinical outcomes and future opportunities

Leptomeningeal disease is a debilitating, late-stage form of metastatic cancer disseminated within the cerebrospinal fluid, subarachnoid space, and leptomeninges, leading to significant neurological morbidity and mortality. As systemic cancer treatments improve, rates of leptomeningeal disease have increased, yet prognosis remains exceedingly poor. A wide range of treatment modalities have been trialed; however, no standard of care has been established. Additionally, many clinical trials exclude patients with leptomeningeal disease, limiting available prospective data. In this review, we discuss the efficacy of immunotherapy for leptomeningeal disease from solid tumors including systemic and intrathecal therapies, as well as combined therapy regimens. Our review indicates a continued deficiency in the current prospective literature and highlights ongoing research regarding the leptomeningeal immune microenvironment, which will be critical in directing future study of leptomeningeal disease treatment. Currently, the efficacy of immunotherapies on leptomeningeal disease appears limited, and further prospective research is needed to draw significant conclusions. However, recent advancement in understanding the leptomeningeal microenvironment points to potential efficacy of novel immunotherapies targeting the innate immune system, and further study is warranted to evaluate the efficacy of these treatments in this subpopulation of patients.

In vivo gene editing and in situ generation of chimeric antigen receptor cells for next-generation cancer immunotherapy

Chimeric antigen receptor (CAR) cell therapy has achieved groundbreaking success in treating hematological malignancies. However, its application to solid tumors remains challenging due to complex manufacturing processes, limited in vivo persistence, and transient therapeutic effects. In vivo CAR-immune cells induced by gene delivery systems loaded with CAR genes and gene-editing tools have shown efficiency for anti-tumor immunotherapy. In situ programming of autologous immune cells avoids the safety concerns of allogeneic immune cells, and the manufacture of gene delivery systems could be standardized. Therefore, the in vivo editing and in situ generation of CAR-immune cells might potentially overcome the abovementioned limitations of current CAR cell therapy. This review mainly focuses on CAR structures, gene-editing tools, and gene delivery techniques applied in anti-tumor immunotherapy to help design and develop in situ CAR-immune cell therapy. The recent applications of in vivo CAR-immune cell therapy in both hematologic malignancies and solid tumors are investigated. To sum up, the in vivo editing and in situ generation of CAR therapy holds promise for offering a practical, cost-effective, efficient, safe, and widely applicable approach to the next-generation anti-tumor immunotherapy.

Potential applications of macrophages in cancer immunotherapy

Immunotherapy has improved cancer treatment based on investigations of tumor immune escape. Manipulation of the immune system stimulates antitumor immune responses and blocks tumor immune escape routes. Genetically adoptive cell therapy, such as T cells, has yielded promising results for hematologic malignancies, but their application to solid tumors has been challenging. Macrophages have a wide broad of capabilities in regulating immune responses, homeostasis, and tissue development, as well as the ability to phagocyte, present antigens, and infiltrate the tumor microenvironment (TME). Given the importance of macrophages in cancer development, they could serve as novel tool for tumor treatment. Therefore, macrophages are used in different formats for direct and indirect targeting of tumor cells. This review summarized the available data on the various applications of macrophages in cancer immunotherapy.

CAR Macrophages: a promising novel immunotherapy for solid tumors and beyond

With the advent of adoptive cellular therapy, chimeric antigen receptor (CAR)-T cell therapy has gained widespread application in cancer treatment and has demonstrated significant efficacy against certain hematologic malignancies. However, due to the limitations of CAR-T cell therapy in treating solid tumors, other immune cells are being modified with CAR to address this issue. Macrophages have emerged as a promising option, owing to their extensive immune functions, which include antigen presentation, powerful tumor phagocytosis, and particularly active trafficking to the tumor microenvironment. Leveraging their unique advantages, CAR-macrophages (CAR-M) are expected to enhance the effectiveness of solid tumor treatments as a novel form of immunotherapy, potentially overcoming major challenges associated with CAR-T/NK therapy. This review outlines the primary mechanism underlying CAR-M and recent progressions in CAR-M therapy, while also discussing their further applications.

GPR65 contributes to constructing immunosuppressive microenvironment in glioma

Glioma, especially glioblastoma patients, present highly heterogeneous and immunosuppressive microenvironment, leading to their poor response to treatment and survival. Targeting the tumor microenvironment is considered a promising therapeutic strategy. M2 macrophages are highly infiltrated in glioma tissue, even up to 50% of the total number of bulk tissue cells. Here, we identified GPR65 as the hub gene of the M2 macrophage-related module in glioma through WGCNA analysis. The expression and prognosis analysis suggested that GPR65 was positively correlated with the malignancy and poor prognosis of glioma, and the heterogeneity analysis found that GPR65 was highly expressed in the vascular proliferation area of glioma, which matched the spatial expression characteristics of M2 macrophages. We further verified that GPR65 was highly expressed in macrophages but not tumor cells in the glioma microenvironment by single-cell data analysis and immunofluorescence. Most importantly, we found that inhibition of GPR65 was sufficient to reduce macrophages' polarization response to glioma cell and break the malignant cooperation with glioma cells. Our study reports the expression characteristics and malignant behavior of GPR65 in the glioma microenvironment, which provides a new alternative target of treatment to glioma microenvironment.

Beyond CAR T cells: exploring alternative cell sources for CAR-like cellular therapies

Chimeric antigen receptor (CAR)-T cell therapy has led to remarkable clinical outcomes in the treatment of hematological malignancies. However, challenges remain, such as limited infiltration into solid tumors, inadequate persistence, systemic toxicities, and manufacturing insufficiencies. The use of alternative cell sources for CAR-based therapies, such as natural killer cells (NK), macrophages (MΦ), invariant Natural Killer T (iNKT) cells, γδT cells, neutrophils, and induced pluripotent stem cells (iPSC), has emerged as a promising avenue. By harnessing these cells' inherent cytotoxic mechanisms and incorporating CAR technology, common CAR-T cell-related limitations can be effectively mitigated. We herein present an overview of the tumoricidal mechanisms, CAR designs, and manufacturing processes of CAR-NK cells, CAR-MΦ, CAR-iNKT cells, CAR-γδT cells, CAR-neutrophils, and iPSC-derived CAR-cells, outlining the advantages, limitations, and potential solutions of these therapeutic strategies.

Contemporary Approaches to Immunotherapy of Solid Tumors

In recent years, the arrival of the immunotherapy industry has introduced the possibility of providing transformative, durable, and potentially curative outcomes for various forms of malignancies. However, further research has shown that there are a number of issues that significantly reduce the effectiveness of immunotherapy, especially in solid tumors. First of all, these problems are related to the protective mechanisms of the tumor and its microenvironment. Currently, major efforts are focused on overcoming protective mechanisms by using different adoptive cell therapy variants and modifications of genetically engineered constructs. In addition, a complex workforce is required to develop and implement these treatments. To overcome these significant challenges, innovative strategies and approaches are necessary to engineer more powerful variations of immunotherapy with improved antitumor activity and decreased toxicity. In this review, we discuss recent innovations in immunotherapy aimed at improving clinical efficacy in solid tumors, as well as strategies to overcome the limitations of various immunotherapies.

Convection-Enhanced Drug Delivery: Experimental and Analytical Studies of Infusion Behavior in an In Vitro Brain Surrogate

Convection-enhanced drug delivery (CED) directly infuses drugs with a large molecular weight toward target cells as a therapeutic strategy for neurodegenerative diseases and brain cancers. Despite the success of many previous in vitro experiments on CED, challenges still remain. In particular, a theoretical predictive model is needed to form a basis for treatment planning, and developing such a model requires well-controlled injection tests that can rigorously capture the convective (advective) and diffusive transport of an infusate. For this purpose, we investigated the advection-diffusion transport of an infusate (bromophenol blue solution) in the brain surrogate (0.2% w/w agarose gel) at different injection rates, ranging from 0.25 to 4 μL/min, by closely monitoring changes in the color intensity, propagation distance, and injection pressures. One dimensional closed-form solution was examined with two variable sets, such as the mathematically calculated coefficient of molecular diffusion and average velocity, and the hydraulic dispersion coefficient and seepage velocity by the least squared method. As a result, the seepage velocity was greater than the average velocity to some extent, particularly for the later infusion times. The poroelastic deformation in the brain surrogate might lead to changes in porosity, and consequently, slight increases in the actual flow velocity as infusion continues. The limitation of efficiency of the single catheter was analyzed by dimensionless analysis. Lastly, this study suggests a simple but robust approach that can properly capture the convective (advective) and diffusive transport of an infusate in an in vitro brain surrogate via well-controlled injection tests.

A new era of cancer immunotherapy: combining revolutionary technologies for enhanced CAR-M therapy

Significant advancements have been made in the application of chimeric antigen receptor (CAR)-T treatment for blood cancers during the previous ten years. However, its effectiveness in treating solid tumors is still lacking, necessitating the exploration of alternative immunotherapies that can overcome the significant challenges faced by current CAR-T cells. CAR-based immunotherapy against solid tumors shows promise with the emergence of macrophages, which possess robust phagocytic abilities, antigen-presenting functions, and the ability to modify the tumor microenvironment and stimulate adaptive responses. This paper presents a thorough examination of the latest progress in CAR-M therapy, covering both basic scientific studies and clinical trials. This study examines the primary obstacles hindering the realization of the complete potential of CAR-M therapy, as well as the potential strategies that can be employed to overcome these hurdles. With the emergence of revolutionary technologies like in situ genetic modification, synthetic biology techniques, and biomaterial-supported gene transfer, which provide a wider array of resources for manipulating tumor-associated macrophages, we suggest that combining these advanced methods will result in the creation of a new era of CAR-M therapy that demonstrates improved efficacy, safety, and availability.

CAR products from novel sources: a new avenue for the breakthrough in cancer immunotherapy

Chimeric antigen receptor (CAR) T cell therapy has transformed cancer immunotherapy. However, significant challenges limit its application beyond B cell-driven malignancies, including limited clinical efficacy, high toxicity, and complex autologous cell product manufacturing. Despite efforts to improve CAR T cell therapy outcomes, there is a growing interest in utilizing alternative immune cells to develop CAR cells. These immune cells offer several advantages, such as major histocompatibility complex (MHC)-independent function, tumor microenvironment (TME) modulation, and increased tissue infiltration capabilities. Currently, CAR products from various T cell subtypes, innate immune cells, hematopoietic progenitor cells, and even exosomes are being explored. These CAR products often show enhanced antitumor efficacy, diminished toxicity, and superior tumor penetration. With these benefits in mind, numerous clinical trials are underway to access the potential of these innovative CAR cells. This review aims to thoroughly examine the advantages, challenges, and existing insights on these new CAR products in cancer treatment.

Advances in Engineered Macrophages: A New Frontier in Cancer Immunotherapy

Macrophages, as pivotal cells within the tumour microenvironment, significantly influence the impact of and reactions to treatments for solid tumours. The rapid evolution of bioengineering technology has revealed the vast potential of engineered macrophages in immunotherapy, disease diagnosis, and tissue engineering. Given this landscape, the goal of harnessing and innovating macrophages as a novel strategy for solid tumour immunotherapy cannot be overstated. The diverse strategies for engineered macrophages in the realm of cancer immunotherapy, encompassing macrophage drug delivery systems, chimeric antigen receptor macrophage therapy, and synergistic treatment approaches involving bacterial outer membrane vesicles and macrophages, are meticulously examined in this review. These methodologies are designed to enhance the therapeutic efficacy of macrophages against solid tumours, particularly those that are drug-resistant and metastatic. Collectively, these immunotherapies are poised to supplement and refine current solid tumour treatment paradigms, thus heralding a new frontier in the fight against malignant tumours.

In Situ Reprogramming of Immune Cells Using Synthetic Nanomaterials

In the past decade, adoptive cell therapy with chimeric antigen receptor-T (CAR-T) cells has revolutionized cancer treatment. However, the complexity and high costs involved in manufacturing current adoptive cell therapy greatly inhibit its widespread availability and access. To address this, in situ cell therapy, which directly reprograms immune cells inside the body, has recently been developed as a promising alternative. Here, an overview of the recent progress in the development of synthetic nanomaterials is provided to deliver plasmid DNA or mRNA for in situ reprogramming of T cells and macrophages, focusing especially on in situ CAR therapies. Also, the main challenges for in situ immune cell reprogramming are discussed and some approaches to overcome these barriers to fulfill the clinical applications are proposed.

The CAR macrophage cells, a novel generation of chimeric antigen-based approach against solid tumors

Today, adoptive cell therapy has many successes in cancer therapy, and this subject is brilliant in using chimeric antigen receptor T cells. The CAR T cell therapy, with its FDA-approved drugs, could treat several types of hematological malignancies and thus be very attractive for treating solid cancer. Unfortunately, the CAR T cell cannot be very functional in solid cancers due to its unique features. This treatment method has several harmful adverse effects that limit their applications, so novel treatments must use new cells like NK cells, NKT cells, and macrophage cells. Among these cells, the CAR macrophage cells, due to their brilliant innate features, are more attractive for solid tumor therapy and seem to be a better candidate for the prior treatment methods. The CAR macrophage cells have vital roles in the tumor microenvironment and, with their direct effect, can eliminate tumor cells efficiently. In addition, the CAR macrophage cells, due to being a part of the innate immune system, attended the tumor sites. With the high infiltration, their therapy modulations are more effective. This review investigates the last achievements in CAR-macrophage cells and the future of this immunotherapy treatment method.

Advancing CAR-based immunotherapies in solid tumors: CAR- macrophages and neutrophils

Macrophages and neutrophils are the main components of the innate immune system and play important roles in promoting angiogenesis, extracellular matrix remodeling, cancer cell proliferation, and metastasis in the tumor microenvironment (TME). They can also be harnessed to mediate cytotoxic tumor killing effects and orchestrate effective anti-tumor immune responses with proper stimulation and modification. Therefore, macrophages and neutrophils have strong potential in cancer immunotherapy. In this review, we briefly outlined the applications of macrophages or neutrophils in adoptive cell therapies, and focused on chimeric antigen receptor (CAR)-engineered macrophages (CAR-Ms) and neutrophils (CAR-Ns). We summarized the construction strategies, the preclinical and clinical studies of CAR-Ms and CAR-Ns. In the end, we briefly discussed the limitations and challenges of CAR-Ms and CAR-Ns, as well as future research directions to extend their applications in treating solid tumors.

Good CARMA: Turning bad tumor-resident myeloid cells good with chimeric antigen receptor macrophages

In religious philosophy, the concept of karma represents the effect of one's past and present actions on one's future. Macrophages are highly plastic cells with myriad roles in health and disease. In the setting of cancer, macrophages are among the most plentiful members of the immune microenvironment where they generally support tumor growth and restrain antitumor immunity. However, macrophages are not necessarily born bad. Macrophages or their immediate progenitors, monocytes, are induced to traffic to the tumor microenvironment (TME) and during this process they are polarized toward a tumor-promoting phenotype. Efforts to deplete or repolarize tumor-associated macrophages (TAM) for therapeutic benefit in cancer have to date disappointed. By contrast, genetic engineering of macrophages followed by their transit into the TME may allow these impressionable cells to mend their ways. In this review, we summarize and discuss recent advances in the genetic engineering of macrophages for the treatment of cancer.

Sophisticated genetically engineered macrophages, CAR-Macs, in hitting the bull's eye for solid cancer immunotherapy approaches

Studies have begun to employ macrophages engineered with chimeric antigen receptor (CAR-Macs) against solid tumors since they can enter solid tumor tissue and interact with approximately all cellular components in the tumor microenvironment. The chimeric antigen receptor (CAR) has emerged as an appealing strategy for improving immune cells' ability to detect cancer. Tumor-associated macrophages (TAMs) generated with CAR designs exhibit appropriate potency based on their capacity to enter solid tumors and communicate through the inhibitory tumor microenvironment. CAR-Macs technology is a new therapeutic method for attacking cancer cells by switching pro-tumoral M2 macrophages to anti-tumoral M1 macrophages, enhancing macrophage phagocytosis, or increasing antigen presentation activity. CAR-Macs may have a prevailing impact on surrounding immune cells, indicating that they retain anti-tumor activity in the presence of human M2 macrophages, demonstrating their use in CAR technology. Understanding the biology of TAM and targeting novel domains for the advanced CAR-Macrophage platform, it will be feasible to add a new dimension to immunotherapy techniques used exclusively in solid malignancies. This review describes how CAR-Macs technologies modulate CAR-Macrophage production, potential target biomarkers on these platforms, their role in immunotherapeutic approaches, and tumor microenvironment.