A new strategy for enhancing antitumor immune response using dendritic cells loaded with chemo-resistant cancer stem-like cells in experimental mice model

Targeted immunotherapy to cancer stem cells: A novel strategy of anticancer immunotherapy

Cancer is a major disease that endangers human health. Cancer drug resistance and relapse are the two main causes contributing to cancer treatment failure. Cancer stem cells (CSCs) are a small fraction of tumor cells that are responsible for tumorigenesis, metastasis, relapse, and resistance to conventional anticancer therapies. Therefore, CSCs are considered to be the root of cancer recurrence, metastasis, and drug resistance. Novel anticancer strategies need to face this new challenge and explore their efficacy against CSCs. Recently, immunotherapy has made rapid advances in cancer treatment, and its potential against CSCs is also an interesting area of research. Meanwhile, immunotherapy strategies are novel therapeutic modalities with promising results in targeting CSCs. In this review, we summarize the targeting of CSCs by various immunotherapy strategies such as monoclonal antibodies(mAb), tumor vaccines, immune checkpoint inhibitors, and chimeric antigen receptor-T cells(CAR-T) in pre-clinical and clinical studies. This review provides new insights into the application of these immunotherapeutic approaches to potential anti-tumor therapies in the future.

Efficacy of Whole Cancer Stem Cell-Based Vaccines: A Systematic Review of Preclinical and Clinical Studies

BACKGROUND

Despite the conventional cancer therapeutic, cancer treatment remains a medical challenge due to neoplasm metastasis and cancer recurrence; therefore, new approaches promoting therapeutic strategies are highly desirable. As a new therapy, the use of whole neoplastic stem cells or cancer stem cell (CSC)-based vaccines is one strategy to overcome these obstacles. We investigated the effects of whole CSC-based vaccines on the solid tumor development, metastasis, and survival rate.

METHODS

Primary electronic databases (PubMed/MEDLINE, Scopus, Embase, and Web of Science) and a major clinical registry were searched. Interventional studies of whole CSC-based vaccines in rodent cancer models (38 studies) and human cancer patients (11 studies) were included; the vaccine preparation methodologies, effects, and overall outcomes were evaluated.

RESULTS

Preclinical studies were divided into 4 groups: CSC-lysates/ inactivated-CSC-based vaccines, CSC-lysate-loaded dendritic cell (CSC-DC) vaccines, cytotoxic T-cell (CTL) vaccines generated with CSC-DC (CSC-DC-CTL), and combinatorial treatments carried out in the prophylactic and therapeutic experimental models. The majority of preclinical studies reported a promising effect on tumor growth, survival rate, and metastasis. Moreover, whole CSC-based vaccines induced several antitumor immune responses. A small number of clinical investigations suggested that the whole CSC-based vaccine treatment is beneficial; however, further research is required.

CONCLUSIONS

This comprehensive review provides an overview of the available methods for assessing the efficacy of whole CSC-based vaccines on tumor development, metastasis, and survival rate. In addition, it presents a set of recommendations for designing high-quality clinical studies that may allow to determine the efficacy of whole CSC-based-vaccines in cancer therapy.

Engaging stemness improves cancer immunotherapy

Intra-tumoral immune cells promote the stemness of cancer stem cells (CSCs) in the tumor microenvironment (TME). CSCs promote tumor progression, relapse, and resistance to immunotherapy. Cancer stemness induces the expression of neoantigens and neo-properties in CSCs, creating an opportunity for targeted immunotherapies. Isolation of stem-like T cells or retaining stemness in T clonotypes strategies produces exhaustion-resistance T cells with superior re-expansion capacity and long-lasting responses after adoptive cell therapies. Stem cells-derived NK cells may be the next generation of NK cell products for immunotherapy. Here, we have reviewed mechanisms by which stemness factors modulated the immunoediting of the TME and summarized the potentials of CSCs in the development of immunotherapy regimens, including CAR-T cells, CAR-NK cells, cancer vaccines, and monoclonal antibodies. We have discussed the natural or genetically engineered stem-like T cells and stem cell-derived NK cells with increased cytotoxicity to tumor cells. Finally, we have provided a perspective on approaches that may improve the therapeutic efficacy of these novel adoptive cell-based products in targeting immunosuppressive TME.

Cancer stem cell-immune cell collusion in immunotherapy

Immunotherapy has pioneered a new era of tumor treatment, in which the immune checkpoint blockade (ICB) exerts significant superiority in overcoming tumor immune escape. However, the formation of an immune-suppressive tumor microenvironment (TME) and the lack of effective activation of the immune response have become major obstacles limiting its development. Emerging reports indicate that cancer stem cells (CSCs) potentially play important roles in treatment resistance and progressive relapse, while current research is usually focused on CSCs themselves. In this review, we mainly emphasize the collusions between CSCs and tumor-infiltrating immune cells. We focus on the summary of CSC-immune cell crosstalk signaling pathways in ICB resistance and highlight the application of targeted drugs to improve the ICB response.

Immune evader cancer stem cells direct the perspective approaches to cancer immunotherapy

Exploration of tumor immunity leads to the development of immune checkpoint inhibitors and cell-based immunotherapies which improve the clinical outcomes in several tumor types. However, the poor clinical efficacy of these treatments observed for other tumors could be attributed to the inherent complex tumor microenvironment (TME), cellular heterogeneity, and stemness driven by cancer stem cells (CSCs). CSC-specific characteristics provide the bulk tumor surveillance and resistance to entire eradication upon conventional therapies. CSCs-immune cells crosstalk creates an immunosuppressive TME that reshapes the stemness in tumor cells, resulting in tumor formation and progression. Thus, identifying the immunological features of CSCs could introduce the therapeutic targets with powerful antitumor responses. In this review, we summarized the role of immune cells providing CSCs to evade tumor immunity, and then discussed the intrinsic mechanisms represented by CSCs to promote tumors' resistance to immunotherapies. Then, we outlined potent immunotherapeutic interventions followed by a perspective outlook on the use of nanomedicine-based drug delivery systems for controlled modulation of the immune system.

"Double hit" strategy: Removal of sialic acid from the dendritic cell surface and loading with CD44+/CD24-/low cell lysate inhibits tumor growth and metastasis by targeting breast cancer stem cells

Cancer stem cells (CSCs), which represent the root cause of resistance to conventional treatments, recurrence, and metastasis, constitute the critical point of failure in cancer treatments. Targeting CSCs with dendritic cell (DC)-based vaccines have been an effective strategy, but sialic acids on the surface of DCs limit the interaction with loaded antigens. We hypothesized that removal of sialic acid moieties on immature DCs (iDCs) could significantly affect DC-CSC-antigen loading, thereby leading to DC maturation and improving immune recognition and activity. The lysate of CD44⁺/CD24^-/low breast CSCs (BCSCs) was pulsed with sialidase-treated DCs to obtain mature dendritic cells (mDCs). The roles of cytoskeletal elements in antigen uptake and dendritic cell maturation were determined by immunofluorescence staining, flow cytometry, and cytokine measurement, respectively. To test the efficacy of the vaccine in vivo, CSCs tumor-bearing mice were immunized with iDC or mDC. Pulsing DCs with antigen increased the expression levels of actin, gelsolin, talin, WASp, and Arp2, especially in podosome-like regions. Compared with iDCs, mDCs expressed high levels of CD40, CD80, CD86 costimulatory molecules and increased IL-12 production. Vaccination with mDC: i) increased CD8+ and CD4 + T-cell numbers, ii) prevented tumor growth with anti-mitotic activity and apoptotic induction, iii) suppressed metastasis by decreasing Snail, Slug, and Twist expressions. This study reveals for the first time that sialic acid removal and loading with CSC antigens induces significant molecular, morphological, and functional changes in DCs and that this new DC identity may be considered for future combined immunotherapy strategies against breast tumors.

Chemically Engineered Immune Cell-Derived Microrobots and Biomimetic Nanoparticles: Emerging Biodiagnostic and Therapeutic Tools

Over the past decades, considerable attention has been dedicated to the exploitation of diverse immune cells as therapeutic and/or diagnostic cell-based microrobots for hard-to-treat disorders. To date, a plethora of therapeutics based on alive immune cells, surface-engineered immune cells, immunocytes' cell membranes, leukocyte-derived extracellular vesicles or exosomes, and artificial immune cells have been investigated and a few have been introduced into the market. These systems take advantage of the unique characteristics and functions of immune cells, including their presence in circulating blood and various tissues, complex crosstalk properties, high affinity to different self and foreign markers, unique potential of their on-demand navigation and activity, production of a variety of chemokines/cytokines, as well as being cytotoxic in particular conditions. Here, the latest progress in the development of engineered therapeutics and diagnostics inspired by immune cells to ameliorate cancer, inflammatory conditions, autoimmune diseases, neurodegenerative disorders, cardiovascular complications, and infectious diseases is reviewed, and finally, the perspective for their clinical application is delineated.

Cancer Stem Cells-Key Players in Tumor Relapse

Tumor relapse and treatment failure are unfortunately common events for cancer patients, thus often rendering cancer an uncurable disease. Cancer stem cells (CSCs) are a subset of cancer cells endowed with tumor-initiating and self-renewal capacity, as well as with high adaptive abilities. Altogether, these features contribute to CSC survival after one or multiple therapeutic approaches, thus leading to treatment failure and tumor progression/relapse. Thus, elucidating the molecular mechanisms associated with stemness-driven resistance is crucial for the development of more effective drugs and durable responses. This review will highlight the mechanisms exploited by CSCs to overcome different therapeutic strategies, from chemo- and radiotherapies to targeted therapies and immunotherapies, shedding light on their plasticity as an insidious trait responsible for their adaptation/escape. Finally, novel CSC-specific approaches will be described, providing evidence of their preclinical and clinical applications.

Recent advances in drug delivery systems for targeting cancer stem cells

Cancer stem cells (CSCs) are a subpopulation of cancer cells with functions similar to those of normal stem cells. Although few in number, they are capable of self-renewal, unlimited proliferation, and multi-directional differentiation potential. In addition, CSCs have the ability to escape immune surveillance. Thus, they play an important role in the occurrence and development of tumors, and they are closely related to tumor invasion, metastasis, drug resistance, and recurrence after treatment. Therefore, specific targeting of CSCs may improve the efficiency of cancer therapy. A series of corresponding promising therapeutic strategies based on CSC targeting, such as the targeting of CSC niche, CSC signaling pathways, and CSC mitochondria, are currently under development. Given the rapid progression in this field and nanotechnology, drug delivery systems (DDSs) for CSC targeting are increasingly being developed. In this review, we summarize the advances in CSC-targeted DDSs. Furthermore, we highlight the latest developmental trends through the main line of CSC occurrence and development process; some considerations about the rationale, advantages, and limitations of different DDSs for CSC-targeted therapies were discussed.

Dual-targeted therapeutic strategy combining CSC-DC-based vaccine and cisplatin overcomes chemo-resistance in experimental mice model

BACKGROUND AND PURPOSE

Emerging evidence suggests that one of the main reasons of chemotherapy treatment failure is the development of multi-drug resistance (MDR) associated with cancer stem cells (CSCs). Our aim is to identify a therapeutic strategy based on MDR-reversing agents.

MATERIALS AND METHODS

CSC-enriched Ehrlich carcinoma (EC) cell cultures were prepared by drug-resistant selection method using different concentrations of cisplatin (CIS). Cell cultures following drug exposure were analyzed by flow cytometry for CSC surface markers CD44⁺/CD24^-. We isolated murine bone marrow-derived dendritic cells (DCs) and then used them to prepare CSC-DC vaccine by pulsation with CSC-enriched lysate. DCs were examined by flow cytometry for phenotypic markers. Solid Ehrlich carcinoma bearing mice were injected with the CSC-DC vaccine in conjunction with repeated low doses of CIS. Tumor growth inhibition was evaluated and tumor tissues were excised and analyzed by real-time PCR to determine the relative gene expression levels of MDR and Bcl-2. Histopathological features of tumor tissues excised were examined.

RESULTS AND CONCLUSION

Co-treatment with CSC-DC and CIS resulted in a significant tumor growth inhibition. Furthermore, the greatest response of downregulation of MDR and Bcl-2 relative gene expression were achieved in the same group. In parallel, the histopathological observations demonstrated enhanced apoptosis and absence of mitotic figures in tumor tissues of the co-treatment group. Dual targeting of resistant cancer cells using CSC-DC vaccine along with cisplatin represents a promising therapeutic strategy that could suppress tumor growth, circumvent MDR, and increase the efficacy of conventional chemotherapies.