Third-Generation Anti-CD47-Specific CAR-T Cells Effectively Kill Cancer Cells and Reduce the Genes Expression in Lung Cancer Cell Metastasis

Emerging role of immunogenic cell death in cancer immunotherapy: Advancing next-generation CAR-T cell immunotherapy by combination

Immunogenic cell death (ICD) is a stress-driven form of regulated cell death (RCD) in which dying tumor cells' specific signaling pathways are activated to release damage-associated molecular patterns (DAMPs), leading to the robust anti-tumor immune response as well as a reversal of the tumor immune microenvironment from "cold" to "hot". Chimeric antigen receptor (CAR)-T cell therapy, as a landmark in anti-tumor immunotherapy, plays a formidable role in hematologic malignancies but falls short in solid tumors. The Gordian knot of CAR-T cells for solid tumors includes but is not limited to, tumor antigen heterogeneity or absence, physical and immune barriers of tumors. The combination of ICD induction therapy and CAR-T cell immunotherapy is expected to promote the intensive use of CAR-T cell in solid tumors. In this review, we summarize the characteristics of ICD, stress-responsive mechanism, and the synergistic effect of various ICD-based therapies with CAR-T cells to effectively improve anti-tumor capacity.

BCMA/CD47-directed universal CAR-T cells exhibit excellent antitumor activity in multiple myeloma

BACKGROUND

BCMA-directed autologous chimeric antigen receptor T (CAR-T) cells have shown excellent clinical efficacy in relapsed or refractory multiple myeloma (RRMM), however, the current preparation process for autologous CAR-T cells is complicated and costly. Moreover, the upregulation of CD47 expression has been observed in multiple myeloma, and anti-CD47 antibodies have shown remarkable results in clinical trials. Therefore, we focus on the development of BCMA/CD47-directed universal CAR-T (UCAR-T) cells to improve these limitations.

METHODS

In this study, we employed phage display technology to screen nanobodies against BCMA and CD47 protein, and determined the characterization of nanobodies. Furthermore, we simultaneously disrupted the endogenous TRAC and B2M genes of T cells using CRISPR/Cas9 system to generate TCR and HLA double knock-out T cells, and developed BCMA/CD47-directed UCAR-T cells and detected the antitumor activity in vitro and in vivo.

RESULTS

We obtained fourteen and one specific nanobodies against BCMA and CD47 protein from the immunized VHH library, respectively. BCMA/CD47-directed UCAR-T cells exhibited superior CAR expression (89.13-98.03%), and effectively killing primary human MM cells and MM cell lines. BCMA/CD47-directed UCAR-T cells demonstrated excellent antitumor activity against MM and prolonged the survival of tumor-engrafted NCG mice in vivo.

CONCLUSIONS

This work demonstrated that BCMA/CD47-directed UCAR-T cells exhibited potent antitumor activity against MM in vitro and in vivo, which provides a potential strategy for the development of a novel "off-the-shelf" cellular immunotherapies for the treatment of multiple myeloma.

Current progress of chimeric antigen receptor (CAR) T versus CAR NK cell for immunotherapy of solid tumors

Equipping cancer-fighting immune cells with chimeric antigen receptor (CAR) has gained immense attention for cancer treatment. CAR-engineered T cells (CAR T cells) are the first immune-engineered cells that have achieved brilliant results in anti-cancer therapy. Despite promising anti-cancer features, CAR T cells could also cause fatal side effects and have shown inadequate efficacy in some studies. This has led to the introduction of other candidates for CAR transduction, e.g., Natural killer cells (NK cells). Regarding the better safety profile and anti-cancer properties, CAR-armored NK cells (CAR NK cells) could be a beneficial and suitable alternative to CAR T cells. Since introducing these two cells as anti-cancer structures, several studies have investigated their efficacy and safety, and most of them have focused on hematological malignancies. Solid tumors have unique properties that make them more resistant and less curable cancers than hematological malignancies. In this review article, we conduct a comprehensive review of the structure and properties of CAR NK and CAR T cells, compare the recent experience of immunotherapy with CAR T and CAR NK cells in various solid cancers, and overview current challenges and future solutions to battle solid cancers using CARNK cells.

Acellular scaffold-based approach for in situ genetic engineering of host T-cells in solid tumor immunotherapy

BACKGROUND

Targeted T-cell therapy has emerged as a promising strategy for the treatment of hematological malignancies. However, its application to solid tumors presents significant challenges due to the limited accessibility and heterogeneity. Localized delivery of tumor-specific T-cells using biomaterials has shown promise, however, procedures required for genetic modification and generation of a sufficient number of tumor-specific T-cells ex vivo remain major obstacles due to cost and time constraints.

METHODS

Polyethylene glycol (PEG)-based three-dimensional (3D) scaffolds were developed and conjugated with positively charged poly-L-lysine (PLL) using carbamide chemistry for efficient loading of lentiviruses (LVs) carrying tumor antigen-specific T-cell receptors (TCRs). The physical and biological properties of the scaffold were extensively characterized. Further, the scaffold loaded with OVA-TCR LVs was implanted in B16F10 cells expressing ovalbumin (B16-OVA) tumor model to evaluate the anti-tumor response and the presence of transduced T-cells.

RESULTS

Our findings demonstrate that the scaffolds do not induce any systemic inflammation upon subcutaneous implantation and effectively recruit T-cells to the site. In B16-OVA melanoma tumor-bearing mice, the scaffolds efficiently transduce host T-cells with OVA-specific TCRs. These genetically modified T-cells exhibit homing capability towards the tumor and secondary lymphoid organs, resulting in a significant reduction of tumor size and systemic increase in anti-tumor cytokines. Immune cell profiling revealed a significantly high percentage of transduced T-cells and a notable reduction in suppressor immune cells within the tumors of mice implanted with these scaffolds.

CONCLUSION

Our scaffold-based T-cell therapy presents an innovative in situ localized approach for programming T-cells to target solid tumors. This approach offers a viable alternative to in vitro manipulation of T-cells, circumventing the need for large-scale in vitro generation and culture of tumor-specific T-cells. It offers an off-the-shelf alternative that facilitates the use of host cells instead of allogeneic cells, thereby, overcoming a major hurdle.

Chimeric Antigen Receptor (CAR) T-Cell Therapy for Patients with Lung Cancer: Current Perspectives

Immunotherapy using chimeric antigen receptor (CAR)-engineered T-cells has achieved unprecedented efficacy in selected hematological cancers. However, solid tumors such as lung cancer impose several additional challenges to the attainment of clinical success using this emerging therapeutic modality. Lung cancer is the biggest cause of cancer-related mortality worldwide, accounting for approximately 1.8 million deaths worldwide each year. Obstacles to the development of CAR T-cell immunotherapy for lung cancer include the selection of safe tumor-selective targets, accounting for the large number of candidates that have been evaluated thus far. Tumor heterogeneity is also a key hurdle, meaning that single target-based approaches are susceptible to therapeutic failure through the emergence of antigen null cancers. There is also a need to enable CAR T-cells to traffic efficiently to sites of disease, to infiltrate tumor deposits and to operate within the hostile tumor microenvironment formed by solid tumors, resisting the onset of exhaustion. Multiple immune, metabolic, physical and chemical barriers operate at the core of malignant lesions, with potential for further heterogeneity and evolution in the face of selective therapeutic pressures. Although the extraordinarily adaptable nature of lung cancers has recently been unmasked, immunotherapy using immune checkpoint blockade can achieve long-term disease control in a small number of patients, establishing clinical proof of concept that immunotherapies can control advanced lung carcinomas. This review summarizes pre-clinical CAR T-cell research that is specifically focused on lung cancer in addition to published and ongoing clinical trial activity. A number of advanced engineering strategies are also described which are designed to bridge the gap to the attainment of meaningful efficacy using genetically engineered T-cells.

The CD47-SIRPα axis is a promising target for cancer immunotherapies

Cluster of differentiation 47(CD47) is a transmembrane protein that is ubiquitously found on the surface of many cells in the body and uniquely overexpressed by both solid and hematologic malignant cells. CD47 interacts with signal-regulatory protein α (SIRPα), to trigger a "don't eat me" signal and thereby achieve cancer immune escape by inhibiting macrophage-mediated phagocytosis. Thus, blocking the CD47-SIRPα phagocytosis checkpoint, for release of the innate immune system, is a current research focus. Indeed, targeting the CD47-SIRPα axis as a cancer immunotherapy has shown promising efficacies in pre-clinical outcomes. Here, we first reviewed the origin, structure, and function of the CD47-SIRPα axis. Then, we reviewed its role as a target for cancer immunotherapies, as well as the factors regulating CD47-SIRPα axis-based immunotherapies. We specifically focused on the mechanism and progress of CD47-SIRPα axis-based immunotherapies and their combination with other treatment strategies. Finally, we discussed the challenges and directions for future research and identified potential CD47-SIRPα axis-based therapies that are suitable for clinical application.

CAR-Based Immunotherapy of Solid Tumours-A Survey of the Emerging Targets

Immunotherapy with CAR T-cells has revolutionised the treatment of B-cell and plasma cell-derived cancers. However, solid tumours present a much greater challenge for treatment using CAR-engineered immune cells. In a partner review, we have surveyed data generated in clinical trials in which patients with solid tumours that expressed any of 30 discrete targets were treated with CAR-based immunotherapy. That exercise confirms that efficacy of this approach falls well behind that seen in haematological malignancies, while significant toxic events have also been reported. Here, we consider approximately 60 additional candidates for which such clinical data are not available yet, but where pre-clinical data have provided support for their advancement to clinical evaluation as CAR target antigens.

Building on the backbone of CD47-based therapy in cancer: Combination strategies, mechanisms, and future perspectives

Described as a "don't eat me" signal, CD47 becomes a vital immune checkpoint in cancer. Its interaction with signal regulatory protein alpha (SIRPα) prevents macrophage phagocytosis. In recent years, a growing body of evidences have unveiled that CD47-based combination therapy exhibits a superior anti-cancer effect. Latest clinical trials about CD47 have adopted the regimen of collaborating with other therapies or developing CD47-directed bispecific antibodies, indicating the combination strategy as a general trend of the future. In this review, clinical and preclinical cases about the current combination strategies targeting CD47 are collected, their underlying mechanisms of action are discussed, and ideas from future perspectives are shared.

Tumor buster - where will the CAR-T cell therapy 'missile' go?

Chimeric antigen receptor (CAR) T cell (CAR-T cell) therapy based on gene editing technology represents a significant breakthrough in personalized immunotherapy for human cancer. This strategy uses genetic modification to enable T cells to target tumor-specific antigens, attack specific cancer cells, and bypass tumor cell apoptosis avoidance mechanisms to some extent. This method has been extensively used to treat hematologic diseases, but the therapeutic effect in solid tumors is not ideal. Tumor antigen escape, treatment-related toxicity, and the immunosuppressive tumor microenvironment (TME) limit their use of it. Target selection is the most critical aspect in determining the prognosis of patients receiving this treatment. This review provides a comprehensive summary of all therapeutic targets used in the clinic or shown promising potential. We summarize CAR-T cell therapies’ clinical trials, applications, research frontiers, and limitations in treating different cancers. We also explore coping strategies when encountering sub-optimal tumor-associated antigens (TAA) or TAA loss. Moreover, the importance of CAR-T cell therapy in cancer immunotherapy is emphasized.

Human lung adenocarcinoma CD47 is upregulated by interferon-γ and promotes tumor metastasis

Tumor cells can evade attack by phagocytes by upregulating the self-marker CD47. The mechanisms underlying tumor CD47 upregulation, however, remain unclear. Here, we report that human lung adenocarcinoma CD47 is upregulated by interferon-γ (IFN-γ), the level in the tumor microenvironment of which is markedly increased after tumor metastasis and chemotherapy. The IFN-γ receptor is expressed in various human lung adenocarcinoma tissues regardless of the CD47 protein expression, and lung adenocarcinoma CD47 expression is significantly enhanced following tumor metastasis or chemotherapy treatment. In line with this, CD47 expression in various lung cancer cells is markedly increased by IFN-γ treatment. Mechanistically, IFN-γ promotes CD47 expression by activating interferon regulatory factor-1 (IRF-1), which binds to an IRF-1-binding domain within the CD47 promoter region and increases CD47 transcription. Functionally, IFN-γ-enhanced CD47 expression facilitates human lung cancer cell invasion both in vitro and in vivo, whereas IFN-γ-induced CD47 upregulation and cancer metastasis are blocked by mutating the IRF-1-binding site within the CD47 promoter. Our results reveal IFN-γ-enhanced CD47 expression as a novel mechanism promoting human lung adenocarcinoma progression.

Recent Advances of Tumor Therapy Based on the CD47-SIRPα Axis

Cancer is still a major disease that is currently difficult for humans to overcome. When the expression of the cluster of differentiation 47 (CD47) is upregulated, tumor cells interact with the macrophage inhibitory receptor signal regulatory protein α (SIRPα) to transmit the "Don't eat me" signal, thereby avoiding phagocytosis by the macrophages. Therefore, when the CD47-SIRPα axis is inhibited, the macrophages' phagocytic function can be restored and can also exert antitumor effects. This Review mainly introduces recent advances in tumor therapy targeted on the CD47-SIRPα axis, including the antibody and fusion protein, small molecule, gene therapy, cell therapy, and drug delivery system, to inhibit the function of CD47 expressed on tumor cells and promote tumor phagocytosis by macrophages. In addition, this Review also summarizes the current approaches to avoid anemia, a common side effect of CD47-SIRPα inhibitions, and provides ideas for clinical transformation.

Targeting CD47/SIRPα as a therapeutic strategy, where we are and where we are headed

Immunotherapy using PD-1 and CTLA4 inhibitors to stimulate T cell immunity has achieved significant clinical success. However, only a portion of patients benefit from T cell-based immunotherapy. Macrophages, the most abundant type of innate immune cells in the body, play an important role in eliminating tumor cells and infectious microbes. The phagocytic check point protein CD47 inhibits the phagocytic activity of macrophages through binding to SIRPα expressed on macrophages. Blockade of the interaction between CD47 and SIRPα could restore phagocytic activity and eliminate tumor cells in vitro and in vivo. In this manuscript, we review the mechanism of action and development status of agents (antibodies targeting CD47 and SIRPα, SIRPα-Fc fusion proteins, and bi-specific antibodies) that block CD47/SIRPα interaction in preclinical studies and in the clinical setting. In addition, small molecules, mRNA, and CAR-T/M that target the CD47/SIRPα axis are also reviewed in this article.

Chimeric antigen receptor T cell therapy: challenges and opportunities in lung cancer

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the paradigm in hematological malignancies treatment, driving an ever-expanding number of basic research and clinical trials of genetically engineering T cells to treat solid tumors. CAR T-cell therapies based on the antibodies targeting Mesothelin, CEA, EGFR, EGFR, MUC1, DLL3, and emerging novel targets provide promising efficacy for lung cancer patients. However, clinical application of CAR T-cell therapy against lung cancer remains limited on account of physical and immune barriers, antigen escape and heterogeneity, on-target off-tumor toxicity, and many other reasons. Understanding the evolution of CAR structure and the generalizable requirements for manufacturing CAR T cells as well as the interplay between lung tumor immunology and CAR T cells will improve clinical translation of this therapeutic modality in lung cancer. In this review, we systematically summarize the latest advances in CAR T-cell therapy in lung cancer, focusing on the CAR structure, target antigens, challenges, and corresponding new strategies.

Cancer Therapy Targeting CD47/SIRPα

Simple Summary

The interaction between cluster of differentiation 47 (CD47) on cancer cells and signal regulatory protein alpha (SIRPα) on immune cells, such as macrophages and dendritic cells, generates a “don’t eat me” signal. This is a common mechanism that provides cancer cells an escape from the innate immune system. Several therapeutics directed to CD47 or SIRPα have entered early clinical trials in recent years. In this article, we review the role of CD47/SIRPα axis in cancer, and summarize the literature on the efficacy and safety of therapeutics targeting CD47 or SIRPα. We also discuss the future implementation of these therapeutics in the treatments of various cancer types.

Abstract

In the past decade, the field of cancer immunotherapy has rapidly advanced, establishing a crucial role for immune checkpoint blockers in the treatment of a variety of cancer types. In parallel with these remarkable clinical developments, further efforts have focused on ways of unleashing adaptive immune responses against cancer. CD47, a cell surface molecule overexpressed by several cancer types that facilitates immune escape from macrophages, dendritic cells and natural killer cells, and its ligand SIRPα, have emerged as potential therapeutic targets. A number of agents directed to CD47/SIRPα have been developed and demonstrated preclinical activity. Early phase clinical trials are investigating CD47/SIRPα directed agents with available data, suggesting safety and preliminary activity. Herein, we provide an overview of the mechanistic rationale of targeting CD47/SIRPα axis and associated clinical evidence.