Incorporation of Immune Checkpoint Blockade into Chimeric Antigen Receptor T Cells (CAR-Ts): Combination or Built-In CAR-T

Universal CAR 2.0 to overcome current limitations in CAR therapy

Chimeric antigen receptor (CAR) T cell therapy has effectively complemented the treatment of advanced relapsed and refractory hematological cancers. The remarkable achievements of CD19- and BCMA-CAR T therapies have raised high expectations within the fields of hematology and oncology. These groundbreaking successes are propelling a collective aspiration to extend the reach of CAR therapies beyond B-lineage malignancies. Advanced CAR technologies have created a momentum to surmount the limitations of conventional CAR concepts. Most importantly, innovations that enable combinatorial targeting to address target antigen heterogeneity, using versatile adapter CAR concepts in conjunction with recent transformative next-generation CAR design, offer the promise to overcome both the bottleneck associated with CAR manufacturing and patient-individualized treatment regimens. In this comprehensive review, we delineate the fundamental prerequisites, navigate through pivotal challenges, and elucidate strategic approaches, all aimed at paving the way for the future establishment of multitargeted immunotherapies using universal CAR technologies.

Advances in molecular targeted drugs in combination with CAR-T cell therapy for hematologic malignancies

Molecular targeted drugs and chimeric antigen receptor (CAR) T cell therapy represent specific biological treatments that have significantly improved the efficacy of treating hematologic malignancies. However, they face challenges such as drug resistance and recurrence after treatment. Combining molecular targeted drugs and CAR-T cells could regulate immunity, improve tumor microenvironment (TME), promote cell apoptosis, and enhance sensitivity to tumor cell killing. This approach might provide a dual coordinated attack on cancer cells, effectively eliminating minimal residual disease and overcoming therapy resistance. Moreover, molecular targeted drugs can directly or indirectly enhance the anti-tumor effect of CAR-T cells by inducing tumor target antigen expression, reversing CAR-T cell exhaustion, and reducing CAR-T cell associated toxic side effects. Therefore, combining molecular targeted drugs with CAR-T cells is a promising and novel tactic for treating hematologic malignancies. In this review article, we focus on analyzing the mechanism of therapy resistance and its reversal of CAR-T cell therapy resistance, as well as the synergistic mechanism, safety, and future challenges in CAR-T cell therapy in combination with molecular targeted drugs. We aim to explore the benefits of this combination therapy for patients with hematologic malignancies and provide a rationale for subsequent clinical studies.

Chimeric antigen receptor-based immunotherapy in breast cancer: Recent progress in China

Breast cancer (BC) is the fourth most prevalent cancer in China. Despite conventional treatment strategies, BC patients often have poor therapeutic outcomes, leading to significant global cancer mortality rates. Chimeric antigen receptor (CAR)-based immunotherapy is a promising and innovative approach for cancer treatment that redirects immune cells to attack tumor cells expressing selected tumor antigens (TAs). T cells, natural killer (NK) cells, and macrophages, key components of the immune system, are used in CAR-based immunotherapies. Although remarkable progress has been made with CAR-T cells in hematologic malignancies, the application of CAR-based immunotherapy to BC has lagged. This is partly due to obstacles such as tumor heterogeneity, which is further associated with the TA and BC subtypes, and the immunosuppressive tumor microenvironment (TME). Several combinatorial approaches, including the use of immune checkpoint inhibitors, oncolytic viruses, and antitumor drugs, have been proposed to overcome these obstacles in BC treatment. Furthermore, several CAR-based immunotherapies for BC have been translated into clinical trials. This review provides an overview of the recent progress in CAR-based immunotherapy for BC treatment, including targeting of TAs, consideration of BC subtypes, assessment of the TME, and exploration of combinatorial therapies. The authors focused on preclinical studies and clinical trials of CAR-T cells, CAR-NK cells, and CAR-macrophages especially conducted in China, followed by an internal comparison and discussion of current limits. In conclusion, this review elucidates China's contribution to CAR-based immunotherapies for BC and provides inspiration for further research. PLAIN LANGUAGE SUMMARY: Despite conventional treatment strategies, breast cancer (BC) patients in China often have poor therapeutic outcomes. Chimeric antigen receptor (CAR)-based immunotherapy, a promising approach, can redirect immune cells to kill tumor cells expressing selected tumor antigens (TAs). However, obstacles such as TA selection, BC subtypes, and immunosuppressive tumor microenvironment still exist. Therefore, various combinatorial approaches have been proposed. This article elucidates several Chinese CAR-based preclinical and clinical studies in BC treatment with comparisons of foreign research, and CAR-immune cells are analyzed, providing inspiration for further research.

Efficacy of programmed cell death 1 inhibitor maintenance after chimeric antigen receptor T cells in patients with relapsed/refractory B-cell non-Hodgkin-lymphoma

INTRODUCTION

Chimeric antigen receptor (CAR)-T cells obtained long-term durability in about 30% to 40% of relapsed/refractory (r/r) B-cell non-Hodgkin lymphoma (B-NHL). Maintenance therapy after CAR-T is necessary, and PD1 inhibitor is one of the important maintenance therapy options.

METHODS

A total of 173 r/r B-NHL patients treated with PD1 inhibitor maintenance following CD19/22 CAR-T therapy alone or combined with autologous hematopoietic stem cell transplantation (ASCT) from March 2019 to July 2022 were assessed for eligibility for two trials. There were 81 patients on PD1 inhibitor maintenance therapy.

RESULTS

In the CD19/22 CAR-T therapy trial, the PD1 inhibitor maintenance group indicated superior objective response rate (ORR) (82.9% vs 60%; P = 0.04) and 2-year progression-free survival (PFS) (59.8% vs 21.3%; P = 0.001) than the non-maintenance group. The estimated 2-year overall survival (OS) was comparable in the two groups (60.1% vs 45.1%; P = 0.112). No difference was observed in the peak expansion levels of CD19 CAR-T and CD22 CAR-T between the two groups. The persistence time of CD19 and CD22 CAR-T in the PD1 inhibitor maintenance group was longer than that in the non-maintenance group. In the CD19/22 CAR-T therapy combined with ASCT trial, no significant differences in ORR (81.4% vs 84.8%; P = 0.67), 2-year PFS (72.3% vs 74.9%; P = 0.73), and 2-year OS (84.1% vs 80.7%; P = 0.79) were observed between non-maintenance and PD1 inhibitor maintenance therapy groups. The peak expansion levels and duration of CD19 and CD22 CAR-T were not statistically different between the two groups. During maintenance treatment with PD1 inhibitor, all adverse events were manageable. In the multivariable analyses, type and R3m were independent predictive factors influencing the OS of r/r B-NHL with PD1 inhibitor maintenance after CAR-T therapy.

CONCLUSION

PD1 inhibitor maintenance following CD19/22 CAR-T therapy obtained superior response and survival in r/r B-NHL, but not in the trial of CD19/22 CAR-T cell therapy combined with ASCT.

Boosting immune responses in lung tumor immune microenvironment: A comprehensive review of strategies and adjuvants

The immune system has a substantial impact on the growth and expansion of lung malignancies. Immune cells are encompassed by a stroma comprising an extracellular matrix (ECM) and different cells like stromal cells, which are known as the tumor immune microenvironment (TIME). TME is marked by the presence of immunosuppressive factors, which inhibit the function of immune cells and expand tumor growth. In recent years, numerous strategies and adjuvants have been developed to extend immune responses in the TIME, to improve the efficacy of immunotherapy. In this comprehensive review, we outline the present knowledge of immune evasion mechanisms in lung TIME, explain the biology of immune cells and diverse effectors on these components, and discuss various approaches for overcoming suppressive barriers. We highlight the potential of novel adjuvants, including toll-like receptor (TLR) agonists, cytokines, phytochemicals, nanocarriers, and oncolytic viruses, for enhancing immune responses in the TME. Ultimately, we provide a summary of ongoing clinical trials investigating these strategies and adjuvants in lung cancer patients. This review also provides a broad overview of the current state-of-the-art in boosting immune responses in the TIME and highlights the potential of these approaches for improving outcomes in lung cancer patients.

Anti-CTLA-4 nanobody as a promising approach in cancer immunotherapy

Cancer is one of the most common diseases and causes of death worldwide. Since common treatment approaches do not yield acceptable results in many patients, developing innovative strategies for effective treatment is necessary. Immunotherapy is one of the promising approaches that has been highly regarded for preventing tumor recurrence and new metastases. Meanwhile, inhibiting immune checkpoints is one of the most attractive methods of cancer immunotherapy. Cytotoxic T lymphocyte-associated protein-4 (CTLA-4) is an essential immune molecule that plays a vital role in cell cycle modulation, regulation of T cell proliferation, and cytokine production. This molecule is classically expressed by stimulated T cells. Inhibition of overexpression of immune checkpoints such as CTLA-4 receptors has been confirmed as an effective strategy. In cancer immunotherapy, immune checkpoint-blocking drugs can be enhanced with nanobodies that target immune checkpoint molecules. Nanobodies are derived from the variable domain of heavy antibody chains. These small protein fragments have evolved entirely without a light chain and can be used as a powerful tool in imaging and treating diseases with their unique structure. They have a low molecular weight, which makes them smaller than conventional antibodies while still being able to bind to specific antigens. In addition to low molecular weight, specific binding to targets, resistance to temperature, pH, and enzymes, high ability to penetrate tumor tissues, and low toxicity make nanobodies an ideal approach to overcome the disadvantages of monoclonal antibody-based immunotherapy. In this article, while reviewing the cellular and molecular functions of CTLA-4, the structure and mechanisms of nanobodies' activity, and their delivery methods, we will explain the advantages and challenges of using nanobodies, emphasizing immunotherapy treatments based on anti-CTLA-4 nanobodies.

Autologous engineered T cell receptor therapy in advanced cancer

To overcome challenges associated with adoptive cell therapy (ACT), we developed a personalized autologous T-cell therapy program. Patients with advanced cancer with HLA-A *02:01 allele and tumor expression of PRAME, MAGEA1, MAGEA4, MAGEA8, NY-ESO-1, COL6A3 exon 6, MXRA5, and/or MMP1 underwent leukapheresis and T-cell product manufacturing. Patients received lymphodepletion, IMA101 infusion and interleukin 2 for 14 days. Of 214 screened patients, 14 were treated (6, IMA101; 8, IMA101 and atezolizumab). The most common adverse events were cytokine release syndrome (G1, n = 6; G2, n = 4) and cytopenia. At 6 weeks, 12 (85.7%) patients had stable disease. Three patients had prolonged disease stabilization for 12.9, 7.3, and 13.7 months, respectively. The median progression-free survival and overall survival were 3.4 months and 9.4 months, respectively. Target-specific T cells expanded to constitute up to 78.7% of CD8+ cells. In conclusion, IMA101 was feasible and well tolerated, leveraging the potential of multi-targeted ACT that warrants further investigation.

Advances in CAR-Engineered Immune Cell Generation: Engineering Approaches and Sourcing Strategies

Chimeric antigen receptor T-cell (CAR-T) therapy has emerged as a highly efficacious treatment modality for refractory and relapsed hematopoietic malignancies in recent years. Furthermore, CAR technologies for cancer immunotherapy have expanded from CAR-T to CAR-natural killer cell (CAR-NK), CAR-cytokine-induced killer cell (CAR-CIK), and CAR-macrophage (CAR-MΦ) therapy. Nevertheless, the high cost and complex manufacturing processes of ex vivo generation of autologous CAR products have hampered broader application. There is an urgent need to develop an efficient and economical paradigm shift for exploring new sourcing strategies and engineering approaches toward generating CAR-engineered immune cells to benefit cancer patients. Currently, researchers are actively investigating various strategies to optimize the preparation and sourcing of these potent immunotherapeutic agents. In this work, the latest research progress is summarized. Perspectives on the future of CAR-engineered immune cell manufacturing are provided, and the engineering approaches, and diverse sources used for their development are focused upon.

CAR-modified Cellular Therapies in Chronic Lymphocytic Leukemia: Is the Uphill Road Getting Less Steep?

The clinical development of chimeric antigen receptor (CAR) T-cell therapy has been more challenging for chronic lymphocytic leukemia (CLL) compared to other settings. One of the main reasons is the CLL-associated state of immune dysfunction that specifically involves patient-derived T cells. Here, we provide an overview of the clinical results obtained with CAR T-cell therapy in CLL, describing the identified immunologic reasons for the inferior efficacy. Novel CAR T-cell formulations, such as lisocabtagene maraleucel, administered alone or in combination with the Bruton tyrosine kinase inhibitor ibrutinib, are currently under investigation. These approaches are based on the rationale that improving the quality of the T-cell source and of the CAR T-cell product may deliver a more functional therapeutic weapon. Further strategies to boost the efficacy of CAR T cells should rely not only on the production of CAR T cells with an improved cellular composition but also on additional changes. Such alterations could include (1) the coadministration of immunomodulatory agents capable of counteracting CLL-related immunological alterations, (2) the design of improved CAR constructs (such as third- and fourth-generation CARs), (3) the incorporation into the manufacturing process of immunomodulatory compounds overcoming the T-cell defects, and (4) the use of allogeneic CAR T cells or alternative CAR-modified cellular vectors. These strategies may allow to develop more effective CAR-modified cellular therapies capable of counteracting the more aggressive and still incurable forms of CLL.

Advancing CART therapy for acute myeloid leukemia: recent breakthroughs and strategies for future development

Chimeric antigen receptor (CAR) T therapies are being developed for acute myeloid leukemia (AML) on the basis of the results obtained for other haematological malignancies and the need of new treatments for relapsed and refractory AML. The biggest challenge of CART therapy for AML is to identify a specific target antigen, since antigens expressed in AML cells are usually shared with healthy haematopoietic stem cells (HSC). The concomitant expression of the target antigen on both tumour and HSC may lead to on-target/off-tumour toxicity. In this review, we guide researchers to design, develop, and translate to the clinic CART therapies for the treatment of AML. Specifically, we describe what issues have to be considered to design these therapies; what in vitro and in vivo assays can be used to prove their efficacy and safety; and what expertise and facilities are needed to treat and manage patients at the hospital.

SOHO State of the Art Updates and Next Questions | From Biology to Therapy: Progress in Hodgkin Lymphoma

Classic Hodgkin lymphoma (HL) is a unique lymphoid malignancy where the malignant cells comprise only 1% to 2% of the total tumor cellularity. Over the past 2 decades, the treatment of HL has evolved drastically based on the advent of novel targeted therapies. Novel agents including programmed death-1 (PD-1) inhibitors, antibody-drug conjugates such as brentuximab vedotin, bispecific antibodies, and chimeric antigen receptor (CAR) T cell therapies have served to shape the management of HL in the frontline as well as the relapsed and refractory (R/R) setting. Some of these agents have been incorporated into treatment algorithms, while others are currently under investigation demonstrating promising results. This review focuses on highlighting the underlying tumor biology forming the basis of therapeutics in HL, and reviews some of the emerging and established novel therapies.

Combined or Sequential Treatment with Immune Checkpoint Inhibitors and Car-T Cell Therapies for the Management of Haematological Malignancies: A Systematic Review

The aim of this paper was to review the available evidence on the efficacy and safety of combined or sequential use of PD-1/PD-L1 immune checkpoint inhibitors (ICI) and CAR-T cell therapies in relapsed/refractory (R/R) haematological malignancies. A systematic literature review was performed until 21 November 2022. Inclusion criteria: cohort studies/clinical trials aimed at evaluating the efficacy and/or safety of the combination of CAR-T cell therapy with PD-1/PD-L1 inhibitors in R/R haematological malignancies, which had reported results. Those focusing only on ICI or CAR-T separately or evaluating the combination in other non-hematological solid tumours were excluded. We used a specific checklist for quality assessment of the studies, and then we extracted data on efficacy or efficiency and safety. A total of 1867 articles were identified, and 9 articles were finally included (early phase studies, with small samples of patients and acceptable quality). The main pathologies were B-cell acute lymphoblastic leukaemia (B-ALL) and B-cell non-Hodgkin's lymphoma (B-NHL). The most studied combination was tisagenlecleucel with pembrolizumab. In terms of efficacy, there is great variability: the combination could be a promising option in B-ALL, with modest data, and in B-NHL, although hopeful responses were received, the combination does not appear better than CAR-T cell monotherapy. The safety profile could be considered comparable to that described for CAR-T cell monotherapy.

Targeting and cytotoxicity of chimeric antigen receptor T cells grafted with PD1 extramembrane domain

BACKGROUND

Immunosuppression induced by programmed cell death protein 1 (PD1) presents a significant constraint on the effectiveness of chimeric antigen receptor (CAR)-T therapy. The potential of combining PD1/PDL1 (Programmed cell death 1 ligand 1) axis blockade with CAR-T cell therapy is promising. However, developing a highly efficient and minimally toxic approach requires further exploration. Our attempt to devise a novel CAR structure capable of recognizing both tumor antigens and PDL1 encountered challenges since direct targeting of PDL1 resulted in systemic adverse effects.

METHODS

In this research, we innovatively engineered novel CARs by grafting the PD1 domain into a conventional second-generation (2G) CAR specifically targeting CD19. These CARs exist in two distinct forms: one with PD1 extramembrane domain (EMD) directly linked to a transmembrane domain (TMD), referred to as PE CAR, and the other with PD1 EMD connected to a TMD via a CD8 hinge domain (HD), known as PE8HT CAR. To evaluate their efficacy, we conducted comprehensive assessments of their cytotoxicity, cytokine release, and potential off-target effects both in vitro and in vivo using tumor models that overexpress CD19/PDL1.

RESULTS

The findings of our study indicate that PE CAR demonstrates enhanced cytotoxicity and reduced cytokine release specifically towards CD19 + PDL1 + tumor cells, without off-target effects to CD19-PDL1 + tumor cells, in contrast to 2G CAR-T cells. Additionally, PE CAR showed ameliorative differentiation, exhaustion, and apoptosis phenotypes as assessed by flow cytometry, RNA-sequencing, and metabolic parameter analysis, after encountering CD19 + PDL1 + tumor cells.

CONCLUSION

Our results revealed that CAR grafted with PD1 exhibits enhanced antitumor activity with lower cytokine release and no PD1-related off-target toxicity in tumor models that overexpress CD19 and PDL1. These findings suggest that our CAR design holds the potential for effectively addressing the PD1 signal.

Innovative Strategies of Reprogramming Immune System Cells by Targeting CRISPR/Cas9-Based Genome-Editing Tools: A New Era of Cancer Management

The recent developments in the study of clustered regularly interspaced short palindromic repeats/associated protein 9 (CRISPR/Cas9) system have revolutionized the art of genome-editing and its applications for cellular differentiation and immune response behavior. This technology has further helped in understanding the mysteries of cancer progression and possible designing of novel antitumor immunotherapies. CRISPR/Cas9-based genome-editing is now often used to engineer universal T-cells, equipped with recombinant T-cell receptor (TCR) or chimeric antigen receptor (CAR). In addition, this technology is used in cytokine stimulation, antibody designing, natural killer (NK) cell transfer, and to overcome immune checkpoints. The innovative potential of CRISPR/Cas9 in preparing the building blocks of adoptive cell transfer (ACT) immunotherapy has opened a new window of antitumor immunotherapy and some of them have gained FDA approval. The manipulation of immunogenetic regulators has opened a new interface for designing, implementation and interpretation of CRISPR/Cas9-based screening in immuno-oncology. Several cancers like lymphoma, melanoma, lung, and liver malignancies have been treated with this strategy, once thought to be impossible. The safe and efficient delivery of CRISPR/Cas9 system within the immune cells for the genome-editing strategy is a challenging task which needs to be sorted out for efficient immunotherapy. Several targeting approaches like virus-mediated, electroporation, microinjection and nanoformulation-based methods have been used, but each procedure offers some limitations. Here, we elaborate the recent updates of cancer management through immunotherapy in partnership with CRISPR/Cas9 technology. Further, some innovative methods of targeting this genome-editing system within the immune system cells for reprogramming them, as a novel strategy of anticancer immunotherapy is elaborated. In addition, future prospects and clinical trials are also discussed.

Insight into the Progress in CAR-T Cell Therapy and Combination with Other Therapies for Glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain cancer in adults. It is always resistant to existing treatments, including surgical resection, postoperative radiotherapy, and chemotherapy, which leads to a dismal prognosis and a high relapse rate. Therefore, novel curative therapies are urgently needed for GBM. Chimeric antigen receptor T (CAR-T) cell therapy has significantly improved life expectancy for hematological malignancies patients, and thus it increases the interest in applying CAR-T cell therapy for solid tumors. In the recently published research, it is indicated that there are numerous obstacles to achieve clinical benefits for solid tumors, especially for GBM, because of GBM anatomical characteristics (the blood-brain barrier and suppressive tumor microenvironment) and the tumor heterogeneity. CAR-T cells are difficult to penetrate blood-brain barrier, and immunosuppressive tumor microenvironment (TME), which induces CAR-T cell exhaustion, impairs CAR-T cell therapy response. Moreover, under the pressure of CAR-T cell therapy, the tumor heterogeneity and tumor plasticity drive tumor evolution and therapy resistance, such as antigen escape. Nonetheless, scientists strive for strategies to overcome these hurdles, including novel CAR-T cell designs and regional delivery. For instance, the structure of multi-antigen-targeted CAR-T cells can enrich CAR-T accumulation in tumor TME and eliminate abundant tumor cells to avoid tumor antigen heterogeneity. Additionally, paired with an immune modifier and one or more stimulating domains, different generation of innovations in the structure and manufacturing of CAR-T cells have improved efficacy and persistence. While single CAR-T cell therapy receives limited clinical survival benefit. Compared with single CAR-T cell therapy, the combination therapies have supplemented the treatment paradigm. Combinatorial treatment methods consolidate the CAR-T cells efficacy by regulating the tumor microenvironment, optimizing the CAR structure, targeting the CAR-T cells to the tumor cells, reversing the tumor-immune escape mechanisms, and represent a promising avenue against GBM, based on multiple impressive research. Moreover, exciting results are also reported to be realized through combining effective therapies with CAR-T cells in preclinical and clinical trials samples, have aroused inspiration to explore the antitumor function of combination therapies. In summary, this study aims to summarize the limitation of CAR-T cell therapies and introduces novel strategies to enhance CAR-T cell function as well as prospect the potential of the therapeutic combination.

Efficacy of checkpoint inhibition after CAR-T failure in aggressive B-cell lymphomas: outcomes from 15 US institutions

Checkpoint inhibitor (CPI) therapy with anti-PD-1 antibodies has been associated with mixed outcomes in small cohorts of patients with relapsed aggressive B-cell lymphomas after CAR-T failure. To define CPI therapy efficacy more definitively in this population, we retrospectively evaluated clinical outcomes in a large cohort of 96 patients with aggressive B-cell lymphomas receiving CPI therapy after CAR-T failure across 15 US academic centers. Most patients (53%) had diffuse large B-cell lymphoma, were treated with axicabtagene ciloleucel (53%), relapsed early (≤180 days) after CAR-T (83%), and received pembrolizumab (49%) or nivolumab (43%). CPI therapy was associated with an overall response rate of 19% and a complete response rate of 10%. Median duration of response was 221 days. Median progression-free survival (PFS) and overall survival (OS) were 54 and 159 days, respectively. Outcomes to CPI therapy were significantly improved in patients with primary mediastinal B-cell lymphoma. PFS (128 vs 51 days) and OS (387 vs 131 days) were significantly longer in patients with late (>180 days) vs early (≤180 days) relapse after CAR-T. Grade ≥3 adverse events occurred in 19% of patients treated with CPI. Most patients (83%) died, commonly because of progressive disease. Only 5% had durable responses to CPI therapy. In the largest cohort of patients with aggressive B-cell lymphoma treated with CPI therapy after CAR-T relapse, our results reveal poor outcomes, particularly among those relapsing early after CAR-T. In conclusion, CPI therapy is not an effective salvage strategy for most patients after CAR-T, where alternative approaches are needed to improve post-CAR-T outcomes.

Updated Clinical Perspectives and Challenges of Chimeric Antigen Receptor-T Cell Therapy in Colorectal Cancer and Invasive Breast Cancer

In recent years, the incidence of colorectal cancer (CRC) and breast cancer (BC) has increased worldwide and caused a higher mortality rate due to the lack of selective anti-tumor therapies. Current chemotherapies and surgical interventions are significantly preferred modalities to treat CRC or BC in advanced stages but the prognosis for patients with advanced CRC and BC remains dismal. The immunotherapy technique of chimeric antigen receptor (CAR)-T cells has resulted in significant clinical outcomes when treating hematologic malignancies. The novel CAR-T therapy target antigens include GUCY2C, CLEC14A, CD26, TEM8/ANTXR1, PDPN, PTK7, PODXL, CD44, CD19, CD20, CD22, BCMA, GD2, Mesothelin, TAG-72, CEA, EGFR, B7H3, HER2, IL13Ra2, MUC1, EpCAM, PSMA, PSCA, NKG2D. The significant aim of this review is to explore the recently updated information pertinent to several novel targets of CAR-T for CRC, and BC. We vividly described the challenges of CAR-T therapies when treating CRC or BC. The immunosuppressive microenvironment of solid tumors, the shortage of tumor-specific antigens, and post-treatment side effects are the major hindrances to promoting the development of CAR-T cells. Several clinical trials related to CAR-T immunotherapy against CRC or BC have already been in progress. This review benefits academicians, clinicians, and clinical oncologists to explore more about the novel CAR-T targets and overcome the challenges during this therapy.

Feasibility and Safety of Personalized, Multi-Target, Adoptive Cell Therapy (IMA101): First-in-Human Clinical Trial in Patients with Advanced Metastatic Cancer

IMA101 is an actively personalized, multi-targeted adoptive cell therapy (ACT), whereby autologous T cells are directed against multiple novel defined peptide-HLA (pHLA) cancer targets. HLA-A*02:01-positive patients with relapsed/refractory solid tumors expressing ≥1 of 8 predefined targets underwent leukapheresis. Endogenous T cells specific for up to 4 targets were primed and expanded in vitro. Patients received lymphodepletion (fludarabine, cyclophosphamide), followed by T-cell infusion and low-dose IL2 (Cohort 1). Patients in Cohort 2 received atezolizumab for up to 1 year (NCT02876510). Overall, 214 patients were screened, 15 received lymphodepletion (13 women, 2 men; median age, 44 years), and 14 were treated with T-cell products. IMA101 treatment was feasible and well tolerated. The most common adverse events were cytokine release syndrome (Grade 1, n = 6; Grade 2, n = 4) and expected cytopenias. No patient died during the first 100 days after T-cell therapy. No neurotoxicity was observed. No objective responses were noted. Prolonged disease stabilization was noted in three patients lasting for 13.7, 12.9, and 7.3 months. High frequencies of target-specific T cells (up to 78.7% of CD8+ cells) were detected in the blood of treated patients, persisted for >1 year, and were detectable in posttreatment tumor tissue. Individual T-cell receptors (TCR) contained in T-cell products exhibited broad variation in TCR avidity, with the majority being low avidity. High-avidity TCRs were identified in some patients' products. This study demonstrates the feasibility and tolerability of an actively personalized ACT directed to multiple defined pHLA cancer targets. Results warrant further evaluation of multi-target ACT approaches using potent high-avidity TCRs. See related Spotlight by Uslu and June, p. 865.

Preclinical evaluation of chimeric antigen receptor T cells targeting the carcinoembryonic antigen as a potential immunotherapy for gallbladder cancer

Gallbladder cancer (GBC) is commonly diagnosed at late stages when conventional treatments achieve only modest clinical benefit. Therefore, effective treatments for advanced GBC are needed. In this context, the administration of T cells genetically engineered with chimeric antigen receptors (CAR) has shown remarkable results in hematological cancers and is being extensively studied for solid tumors. Interestingly, GBC tumors express canonical tumor-associated antigens, including the carcinoembryonic antigen (CEA). However, the potential of CEA as a relevant antigen in GBC to be targeted by CAR-T cell-based immunotherapy has not been addressed. Here we show that CEA was expressed in 88% of GBC tumors, with higher levels associated with advanced disease stages. CAR-T cells specifically recognized plate-bound CEA as evidenced by up-regulation of 4-1BB, CD69 and PD-1, and production of effector cytokines IFN-γ and TNF-α. In addition, CD8+ CAR-T cells up-regulated the cytotoxic molecules granzyme B and perforin. Interestingly, CAR-T cell activation occurred even in the presence of PD-L1. Consistent with these results, CAR-T cells efficiently recognized GBC cell lines expressing CEA and PD-L1, but not a CEA-negative cell line. Furthermore, CAR-T cells exhibited in vitro cytotoxicity and reduced in vivo tumor growth of GB-d1 cells. In summary, we demonstrate that CEA represents a relevant antigen for GBC that can be targeted by CAR-T cells at the preclinical level. This study warrants further development of the adoptive transfer of CEA-specific CAR-T cells as a potential immunotherapy for GBC.

Case Report: Severe cutaneous adverse event associated with checkpoint inhibition in the setting of CAR T-cell therapy: beyond CRS

Anti-CD19 chimeric antigen receptor (CAR) T cell therapy actually represents the standard of care for multiple relapsed or refractory primary mediastinal B-cell lymphoma (r/r PMBCL). Checkpoint inhibitors, such as pembrolizumab, appear to be a safe and effective treatment strategy for patients who are ineligible for or resistant to autologous stem cell transplantation. Although preclinical studies suggested that checkpoint inhibitors may enhance the vitality and anti-tumor activity of CAR T cells, there are no substantial/robust clinical data about the immune-mediated toxicity of their association. We describe a case of a severe cutaneous adverse event arising immediately after Cytokine Release Syndrome (CRS) on day +6 from CAR T cells infusion in a young r/r PMBCL patient who previously received pembrolizumab. These skin lesions were interpreted as an immune mediated adverse event, considering their prompt improvement and fully recovering achieved with the addition of immunoglobulin infusion to systemic steroid therapy. This case of life-threatening cutaneous adverse event calls for further investigations about off-target immune-related adverse events deriving from the combination of CAR T cell therapy and checkpoint inhibition, whose synergic therapeutic effect is promising.

Biological Biomarkers of Response and Resistance to Immune Checkpoint Inhibitors in Renal Cell Carcinoma

Renal cell carcinoma (RCC) represents around 2% of cancer-related deaths worldwide per year. RCC is an immunogenic malignancy, and treatment of metastatic RCC (mRCC) has greatly improved since the advent of the new immunotherapy agents, including immune checkpoint inhibitors (ICIs). However, it should be stressed that a large proportion of patients does not respond to these therapies. There is thus an urgent need to identify predictive biomarkers of efficacy or resistance associated with ICIs or ICI/Tyrosine kinase inhibitor (TKI) combinations; this is a major challenge to achieve precision medicine for mRCC in routine practice. To identify potential biomarkers, it is necessary to improve our knowledge on the biology of immune checkpoints. A lot of efforts have been made over the last decade in the field of immuno-oncology. We summarize here the main data obtained in this field when considering mRCC. As for clinical biomarkers, clinician and scientific experts of the domain are facing difficulties in identifying such molecular entities, probably due to the complexity of immuno-oncology and the constant adaptation of tumor cells to their changing environment.

Recent Advances in CAR-Based Solid Tumor Immunotherapy

Adoptive cell therapy using chimeric antigen receptor (CAR) technology is one of the most advanced engineering platforms for cancer immunotherapy. CAR-T cells have shown remarkable efficacy in the treatment of hematological malignancies. However, their limitations in solid tumors include an immunosuppressive tumor microenvironment (TME), insufficient tumor infiltration, toxicity, and the absence of tumor-specific antigens. Although recent advances in CAR-T cell design-such as the incorporation of co-stimulatory domains and the development of armored CAR-T cells-have shown promising results in treating solid tumors, there are still challenges that need to be addressed. To overcome these limitations, other immune cells, such as natural killer (NK) cells and macrophages (M), have been developed as attractive options for efficient cancer immunotherapy of solid tumors. CAR-NK cells exhibit substantial clinical improvements with "off-the-shelf" availability and low toxicity. CAR-M cells have promising therapeutic potential because macrophages can infiltrate the TME of solid tumors. Here, we review the recent advances and future perspectives associated with engineered immune cell-based cancer immunotherapies for solid tumors. We also summarize ongoing clinical trials investigating the safety and efficacy of engineered immune cells, such as CAR-T, CAR-NK, and CAR-M, for targeting solid tumors.

GD2 CAR-T cells in combination with Nivolumab exhibit enhanced antitumor efficacy

Glioblastoma (GBM) is a common primary brain tumor with poor clinical prognosis. Although CAR-T therapy has been trialed for treatment of GBM, the outcomes are sub-optimal possibly due to exhaustion of T cells and life-threatening neurotoxicity. To address these issues, a combined therapeutic strategy was tested in the current study using GD2 CAR-T together with Nivolumab - an anti-PD-1 monoclonal antibody. An effector-to-target co-culture system was established to evaluate the short-term and long-term cytotoxicity of CAR-T, as well as to investigate the inhibitory activity and T cell exhaustion associated with the PD-1/PD-L1 signaling pathway. Orthotopic NOD/SCID GBM animal models were generated to evaluate the safety and efficacy of the combined therapeutic strategy at various dosages of GD2 CAR-T with Nivolumab. GD2 CAR-T exhibited significant antigen-specific cytotoxicity in a dose-dependent manner in vitro. The persistence of cytotoxicity of GD2 CAR-T could be enhanced by addition of Nivolumab in the co-culture system. Animal studies suggested that GD2 CAR-T effectively infiltrated into tumor tissue and significantly hampered tumor progression. The optimal therapeutic outcome was obtained via using the medium dosage of CAR-T with Nivolumab, which displayed the highest efficacy in extending the survival up to 60 days. Further investigation of toxicity revealed that high-dosage of GD2 CAR-T could induce tumor apoptosis through p53/caspase-3/PARP signaling pathway. This study suggests that GD2 CAR-T in combination with Nivolumab may offer an improved therapeutic strategy for treatment of GBM.

Current status of CAR-T cell therapy for pediatric hematologic malignancies

Acute lymphoblastic leukemia (ALL) is the most common cancer in the pediatric population, and the long-term survival can reach 90%. However, approximately, 20% of pediatric ALL patients experience relapse and require second-line chemotherapy. This is frequently followed by hematopoietic stem cell transplantation, which can cause long-term sequelae. Recent advances in immunotherapy, such as monoclonal antibody therapy and chimeric antigen receptor (CAR)-T cell therapy, have revolutionized the treatment of relapsed and refractory ALL. Anti-CD19 CAR-T cells successfully eliminate B cell malignancies such as ALL. Tisagenlecleucel (Kymriah^®) is the first CAR-T cell immunotherapy approved by the FDA. CAR-T cell therapy can cause specific adverse events (AEs) such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, which are defined and graded according to the consensus grading system and treated with supportive therapies along with tocilizumab and corticosteroids. Other AEs include prolonged bone marrow suppression and hypogammaglobulinemia. Severe AEs are less common in the real-world experience than in clinical trials, probably due to better management of the patient before and during CAR-T cell therapy. The biggest challenge in CAR-T cell therapy against ALL is relapse. A high tumor burden on infusion, early loss of B cell aplasia, and minimal residual disease positivity after CAR-T cell infusion are predictive of relapse. Consolidative stem cell transplantation may improve the long-term outcome. The success of CD19 CAR-T cell therapy against B cell malignancy prompted extensive research into the use of CAR-T cells against other hematologic malignancies such as T cell leukemia or myeloid leukemia.

Allogeneic chimeric antigen receptor-T cells with CRISPR-disrupted programmed death-1 checkpoint exhibit enhanced functional fitness

BACKGROUND AIMS

Therapeutic disruption of immune checkpoints has significantly advanced the armamentarium of approaches for treating cancer. The prominent role of the programmed death-1 (PD-1)/programmed death ligand-1 axis for downregulating T cell function offers a tractable strategy for enhancing the disease-modifying impact of CAR-T cell therapy.

METHODS

To address checkpoint interference, primary human T cells were genome edited with a next-generation CRISPR-based platform (Cas9 chRDNA) by knockout of the PDCD1 gene encoding the PD-1 receptor. Site-specific insertion of a chimeric antigen receptor specific for CD19 into the T cell receptor alpha constant locus was implemented to drive cytotoxic activity.

RESULTS

These allogeneic CAR-T cells (CB-010) promoted longer survival of mice in a well-established orthotopic tumor xenograft model of a B cell malignancy compared with identically engineered CAR-T cells without a PDCD1 knockout. The persistence kinetics of CB-010 cells in hematologic tissues versus CAR-T cells without PDCD1 disruption were similar, suggesting the robust initial debulking of established tumor xenografts was due to enhanced functional fitness. By single-cell RNA-Seq analyses, CB-010 cells, when compared with identically engineered CAR-T cells without a PDCD1 knockout, exhibited fewer T_reg cells, lower exhaustion phenotypes and reduced dysfunction signatures and had higher activation, glycolytic and oxidative phosphorylation signatures. Further, an enhancement of mitochondrial metabolic fitness was observed, including increased respiratory capacity, a hallmark of less differentiated T cells.

CONCLUSIONS

Genomic PD-1 checkpoint disruption in the context of allogeneic CAR-T cell therapy may provide a compelling option for treating B lymphoid malignancies.

BiTE-Secreting CAR-γδT as a Dual Targeting Strategy for the Treatment of Solid Tumors

HLA-G is considered as an immune checkpoint protein and a tumor-associated antigen. In the previous work, it is reported that CAR-NK targeting of HLA-G can be used to treat certain solid tumors. However, the frequent co-expression of PD-L1 and HLA-G) and up-regulation of PD-L1 after adoptive immunotherapy may decrease the effectiveness of HLA-G-CAR. Therefore, simultaneous targeting of HLA-G and PD-L1 by multi-specific CAR could represent an appropriate solution. Furthermore, gamma-delta T (γδT) cells exhibit MHC-independent cytotoxicity against tumor cells and possess allogeneic potential. The utilization of nanobodies offers flexibility for CAR engineering and the ability to recognize novel epitopes. In this study, Vδ2 γδT cells are used as effector cells and electroporated with an mRNA-driven, nanobody-based HLA-G-CAR with a secreted PD-L1/CD3ε Bispecific T-cell engager (BiTE) construct (Nb-CAR.BiTE). Both in vivo and in vitro experiments reveal that the Nb-CAR.BiTE-γδT cells could effectively eliminate PD-L1 and/or HLA-G-positive solid tumors. The secreted PD-L1/CD3ε Nb-BiTE can not only redirect Nb-CAR-γδT but also recruit un-transduced bystander T cells against tumor cells expressing PD-L1, thereby enhancing the activity of Nb-CAR-γδT therapy. Furthermore, evidence is provided that Nb-CAR.BiTE redirectes γδT into tumor-implanted tissues and that the secreted Nb-BiTE is restricted to the tumor site without apparent toxicity.

CAR-T Cell Therapy: the Efficacy and Toxicity Balance

PURPOSE OF REVIEW

Chimeric antigen receptor (CAR) T cell therapy is an immunotherapy that has resulted in tremendous progress in the treatment of patients with B cell malignancies. However, the remarkable efficacy of therapy is not without significant safety concerns. Herein, we will review the unique and potentially life-threatening toxicities associated with CAR-T cell therapy and their association with treatment efficacy.

RECENT FINDINGS

Currently, CAR-T cell therapy is approved for the treatment of B cell relapsed or refractory leukemia and lymphoma, and most recently, multiple myeloma (MM). In these different diseases, it has led to excellent complete and overall response rates depending on the patient population and therapy. Despite promising efficacy, CAR-T cell therapy is associated with significant side effects; the two most notable toxicities are cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). The treatment of CAR-T-induced toxicity is supportive; however, as higher-grade adverse events occur, toxicity-directed therapy with tocilizumab, an IL-6 receptor antibody, and steroids is standard practice. Overall, a careful risk-benefit balance exists between the efficacy and toxicities of therapies. The challenge lies in the underlying pathophysiology of CAR-T-related toxicity which relies upon the activation of CAR-T cells. Some degree of toxicity is expected to achieve an effective response to therapy, and certain aspects of treatment are also associated with toxicity. As progress is made in the investigation and approval of new CARs, novel toxicity-directed therapies and toxicity-limited constructs will be the focus of attention.

Novel technologies for applying immune checkpoint blockers

Cancer cells develop several ways to subdue the immune system among others via upregulation of inhibitory immune checkpoint (ICP) proteins. These ICPs paralyze immune effector cells and thereby enable unfettered tumor growth. Monoclonal antibodies (mAbs) that block ICPs can prevent immune exhaustion. Due to their outstanding effects, mAbs revolutionized the field of cancer immunotherapy. However, current ICP therapy regimens suffer from issues related to systemic administration of mAbs, including the onset of immune related adverse events, poor pharmacokinetics, limited tumor accessibility and immunogenicity. These drawbacks and new insights on spatiality prompted the exploration of novel administration routes for mAbs for instance peritumoral delivery. Moreover, novel ICP drug classes that are adept to novel delivery technologies were developed to circumvent the drawbacks of mAbs. We therefore review the state-of-the-art and novel delivery strategies of ICP drugs.

T-cell exhaustion in CAR-T-cell therapy and strategies to overcome it

Tumour immunotherapy has achieved good therapeutic effects in clinical practice and has received increased attention. Cytotoxic T cells undoubtedly play an important role in tumour immunotherapy. As a revolutionary tumour immunotherapy approach, chimeric antigen receptor T-cell (CAR-T-cell) therapy has made breakthroughs in the treatment of haematological cancers. However, T cells are easily exhausted in vivo, especially after they enter solid tumours. The exhaustion of T cells can lead to poor results of CAR-T-cell therapy in the treatment of solid tumours. Here, we review the reasons for T-cell exhaustion and how T-cell exhaustion develops. We also review and discuss ways to improve CAR-T-cell therapy effects by regulating T-cell exhaustion.

The New Frontier of Immunotherapy: Chimeric Antigen Receptor T (CAR-T) Cell and Macrophage (CAR-M) Therapy against Breast Cancer

Breast cancer represents one of the most common tumor histologies. To date, based on the specific histotype, different therapeutic strategies, including immunotherapies, capable of prolonging survival are used. More recently, the astonishing results that were obtained from CAR-T cell therapy in haematological neoplasms led to the application of this new therapeutic strategy in solid tumors as well. Our article will deal with chimeric antigen receptor-based immunotherapy (CAR-T cell and CAR-M therapy) in breast cancer.

CAR-cell therapy in the era of solid tumor treatment: current challenges and emerging therapeutic advances

In the last decade, Chimeric Antigen Receptor (CAR)-T cell therapy has emerged as a promising immunotherapeutic approach to fight cancers. This approach consists of genetically engineered immune cells expressing a surface receptor, called CAR, that specifically targets antigens expressed on the surface of tumor cells. In hematological malignancies like leukemias, myeloma, and non-Hodgkin B-cell lymphomas, adoptive CAR-T cell therapy has shown efficacy in treating chemotherapy refractory patients. However, the value of this therapy remains inconclusive in the context of solid tumors and is restrained by several obstacles including limited tumor trafficking and infiltration, the presence of an immunosuppressive tumor microenvironment, as well as adverse events associated with such therapy. Recently, CAR-Natural Killer (CAR-NK) and CAR-macrophages (CAR-M) were introduced as a complement/alternative to CAR-T cell therapy for solid tumors. CAR-NK cells could be a favorable substitute for CAR-T cells since they do not require HLA compatibility and have limited toxicity. Additionally, CAR-NK cells might be generated in large scale from several sources which would suggest them as promising off-the-shelf product. CAR-M immunotherapy with its capabilities of phagocytosis, tumor-antigen presentation, and broad tumor infiltration, is currently being investigated. Here, we discuss the emerging role of CAR-T, CAR-NK, and CAR-M cells in solid tumors. We also highlight the advantages and drawbacks of CAR-NK and CAR-M cells compared to CAR-T cells. Finally, we suggest prospective solutions such as potential combination therapies to enhance the efficacy of CAR-cells immunotherapy.

Emerging frontiers in immuno- and gene therapy for cancer

BACKGROUND AIMS

The field of cell and gene therapy in oncology has moved rapidly since 2017 when the first cell and gene therapies, Kymriah followed by Yescarta, were approved by the Food and Drug Administration in the United States, followed by multiple other countries. Since those approvals, several new products have gone on to receive approval for additional indications. Meanwhile, efforts have been made to target different cancers, improve the logistics of delivery and reduce the cost associated with novel cell and gene therapies. Here, we highlight various cell and gene therapy-related technologies and advances that provide insight into how these new technologies will speed the translation of these therapies into the clinic.

CONCLUSIONS

In this review, we provide a broad overview of the current state of cell and gene therapy-based approaches for cancer treatment - discussing various effector cell types and their sources, recent advances in both CAR and non-CAR genetic modifications, and highlighting a few promising approaches for increasing in vivo efficacy and persistence of therapeutic drug products.

Targeting immune checkpoints: how to use natural killer cells for fighting against solid tumors

Natural killer (NK) cells are unique innate immune cells that mediate anti-viral and anti-tumor responses. Thus, they might hold great potential for cancer immunotherapy. NK cell adoptive immunotherapy in humans has shown modest efficacy. In particular, it has failed to demonstrate therapeutic efficiency in the treatment of solid tumors, possibly due in part to the immunosuppressive tumor microenvironment (TME), which reduces NK cell immunotherapy's efficiencies. It is known that immune checkpoints play a prominent role in creating an immunosuppressive TME, leading to NK cell exhaustion and tumor immune escape. Therefore, NK cells must be reversed from their dysfunctional status and increased in their effector roles in order to improve the efficiency of cancer immunotherapy. Blockade of immune checkpoints can not only rescue NK cells from exhaustion but also augment their robust anti-tumor activity. In this review, we discussed immune checkpoint blockade strategies with a focus on chimeric antigen receptor (CAR)-NK cells to redirect NK cells to cancer cells in the treatment of solid tumors.

Chimeric antigen receptor T-cell therapy for multiple myeloma

Multiple myeloma (MM) is a malignant plasma cell disorder that remains incurable for most patients, as persistent clonal evolution drives new mutations which confer MM high-risk signatures and resistance to standard care. The past two decades have significantly refashioned the therapeutic options for MM, especially adoptive T cell therapy contributing to impressive response rate and clinical efficacy. Despite great promises achieved from chimeric antigen receptor T-cell (CAR-T) therapy, the poor durability and severe toxicity (cytokine release syndrome and neurotoxicity) are still huge challenges. Therefore, relapsed/refractory multiple myeloma (RRMM), characterized by the nature of clinicopathologic and molecular heterogeneity, is frequently associated with poor prognosis. B Cell Maturation Antigen (BCMA) is the most successful target for CAR-T therapy, and other potential targets either for single-target or dual-target CAR-T are actively being studied in numerous clinical trials. Moreover, mechanisms driving resistance or relapse after CAR-T therapy remain uncharacterized, which might refer to T-cell clearance, antigen escape, and immunosuppressive tumor microenvironment. Engineering CAR T-cell to improve both efficacy and safety continues to be a promising area for investigation. In this review, we aim to describe novel tumor-associated neoantigens for MM, summarize the data from current MM CAR-T clinical trials, introduce the mechanism of disease resistance/relapse after CAR-T infusion, highlight innovations capable of enhanced efficacy and reduced toxicity, and provide potential directions to optimize manufacturing processes.

Mechanisms of CAR T cell exhaustion and current counteraction strategies

The functional state of chimeric antigen receptor T (CAR T) cells determines their efficacy in vivo. Exhausted CAR T cells exhibit decreased proliferative capacity, impaired anti-tumor activity, and attenuated persistence. CAR T cell exhaustion has been recognized as a vital cause of nonresponse and relapse after CAR T cell therapy. However, the triggers and mechanisms leading to CAR T cell exhaustion remain blurry and complicated. Therefore, it is essential to clear the regulation network of CAR T cell exhaustion and explore potent solutions. Here, we review the diverse inducers of CAR T cell exhaustion in terms of manufacture process and immunosuppressive tumor microenvironment. In addition to the admitted immune checkpoint blockade, we also describe promising strategies that may reverse CAR T cell exhaustion including targeting the tumor microenvironment, epigenetics and transcriptomics.

Modern Advances in CARs Therapy and Creating a New Approach to Future Treatment

Genetically engineered T and NK cells expressing a chimeric antigen receptor (CAR) are promising cytotoxic cells for the treatment of hematological malignancies and solid tumors. Despite the successful therapies using CAR-T cells, they have some disadvantages, such as cytokine release syndrome (CRS), neurotoxicity, or graft-versus-host-disease (GVHD). CAR-NK cells have lack or minimal cytokine release syndrome and neurotoxicity, but also multiple mechanisms of cytotoxic activity. NK cells are suitable for developing an "off the shelf" therapeutic product that causes little or no graft versus host disease (GvHD), but they are more sensitive to apoptosis and have low levels of gene expression compared to CAR-T cells. To avoid these adverse effects, further developments need to be considered to enhance the effectiveness of adoptive cellular immunotherapy. A promising approach to enhance the effectiveness of adoptive cellular immunotherapy is overcoming terminal differentiation or senescence and exhaustion of T cells. In this case, EVs derived from immune cells in combination therapy with drugs may be considered in the treatment of cancer patients, especially effector T and NK cells-derived exosomes with the cytotoxic activity of their original cells.

Advances in CAR T cell immunotherapy for paediatric brain tumours

Brain tumours are the most common solid tumour in children and the leading cause of cancer related death in children. Current treatments include surgery, chemotherapy and radiotherapy. The need for aggressive treatment means many survivors are left with permanent severe disability, physical, intellectual and social. Recent progress in immunotherapy, including genetically engineered T cells with chimeric antigen receptors (CARs) for treating cancer, may provide new avenues to improved outcomes for patients with paediatric brain cancer. In this review we discuss advances in CAR T cell immunotherapy, the major CAR T cell targets that are in clinical and pre-clinical development with a focus on paediatric brain tumours, the paediatric brain tumour microenvironment and strategies used to improve CAR T cell therapy for paediatric tumours.

CAR-T cell therapy in triple-negative breast cancer: Hunting the invisible devil

Triple-negative breast cancer (TNBC) is known as the most intricate and hard-to-treat subtype of breast cancer. TNBC cells do not express the well-known estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expressed by other breast cancer subtypes. This phenomenon leaves no room for novel treatment approaches including endocrine and HER2-specific antibody therapies. To date, surgery, radiotherapy, and systemic chemotherapy remain the principal therapy options for TNBC treatment. However, in numerous cases, these approaches either result in minimal clinical benefit or are nonfunctional, resulting in disease recurrence and poor prognosis. Nowadays, chimeric antigen receptor T cell (CAR-T) therapy is becoming more established as an option for the treatment of various types of hematologic malignancies. CAR-Ts are genetically engineered T lymphocytes that employ the body’s immune system mechanisms to selectively recognize cancer cells expressing tumor-associated antigens (TAAs) of interest and efficiently eliminate them. However, despite the clinical triumph of CAR-T therapy in hematologic neoplasms, CAR-T therapy of solid tumors, including TNBC, has been much more challenging. In this review, we will discuss the success of CAR-T therapy in hematological neoplasms and its caveats in solid tumors, and then we summarize the potential CAR-T targetable TAAs in TNBC studied in different investigational stages.

CAR-T cell therapy in triple-negative breast cancer: Hunting the invisible devil

Triple-negative breast cancer (TNBC) is known as the most intricate and hard-to-treat subtype of breast cancer. TNBC cells do not express the well-known estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expressed by other breast cancer subtypes. This phenomenon leaves no room for novel treatment approaches including endocrine and HER2-specific antibody therapies. To date, surgery, radiotherapy, and systemic chemotherapy remain the principal therapy options for TNBC treatment. However, in numerous cases, these approaches either result in minimal clinical benefit or are nonfunctional, resulting in disease recurrence and poor prognosis. Nowadays, chimeric antigen receptor T cell (CAR-T) therapy is becoming more established as an option for the treatment of various types of hematologic malignancies. CAR-Ts are genetically engineered T lymphocytes that employ the body's immune system mechanisms to selectively recognize cancer cells expressing tumor-associated antigens (TAAs) of interest and efficiently eliminate them. However, despite the clinical triumph of CAR-T therapy in hematologic neoplasms, CAR-T therapy of solid tumors, including TNBC, has been much more challenging. In this review, we will discuss the success of CAR-T therapy in hematological neoplasms and its caveats in solid tumors, and then we summarize the potential CAR-T targetable TAAs in TNBC studied in different investigational stages.

Recent findings on chimeric antigen receptor (CAR)-engineered immune cell therapy in solid tumors and hematological malignancies

Advancements in adoptive cell therapy over the last four decades have revealed various new therapeutic strategies, such as chimeric antigen receptors (CARs), which are dedicated immune cells that are engineered and administered to eliminate cancer cells. In this context, CAR T-cells have shown significant promise in the treatment of hematological malignancies. However, many obstacles limit the efficacy of CAR T-cell therapy in both solid tumors and hematological malignancies. Consequently, CAR-NK and CAR-M cell therapies have recently emerged as novel therapeutic options for addressing the challenges associated with CAR T-cell therapies. Currently, many CAR immune cell trials are underway in various human malignancies around the world to improve antitumor activity and reduce the toxicity of CAR immune cell therapy. This review will describe the comprehensive literature of recent findings on CAR immune cell therapy in a wide range of human malignancies, as well as the challenges that have emerged in recent years.

Secretory co-factors in next-generation cellular therapies for cancer

Since chimeric antigen receptor (CAR) T-cell therapies for hematologic malignancies were approved by the U.S. Food and Drug Administration, numerous "next-generation" CAR T cells have been developed to improve their safety, efficacy, and applicability. Although some of these novel therapeutic strategies are promising, it remains difficult to apply these therapies to solid tumors and to control adverse effects, such as cytokine release syndrome and neurotoxicity. CAR T cells are generated using highly scalable genetic engineering techniques. One of the major strategies for producing next-generation CAR T cells involves the integration of useful co-factor(s) into the artificial genetic design of the CAR gene, resulting in next-generation CAR T cells that express both CAR and the co-factor(s). Many soluble co-factors have been reported for CAR T cells and their therapeutic effects and toxicity have been tested by systemic injection; therefore, CAR T cells harnessing secretory co-factors could be close to clinical application. Here, we review the various secretory co-factors that have been reported to improve the therapeutic efficacy of CAR T cells and ameliorate adverse events. In addition, we discuss the different co-factor expression systems that have been used to optimize their beneficial effects. Altogether, we demonstrate that combining CAR T cells with secretory co-factors will lead to next-generation CAR T-cell therapies that can be used against broader types of cancers and might provide advanced tools for more complicated synthetic immunotherapies.

Chimeric Antigen Receptor T-cell Therapy: Current Status and Clinical Outcomes in Pediatric Hematologic Malignancies

Chimeric antigen receptor T-cell (CART) therapy has transformed the treatment paradigm for pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL), with complete remission rates in key pivotal CD19-CART trials ranging from 65% to 90%. Alongside this new therapy, new toxicity profiles and treatment limitations have emerged, necessitating toxicity consensus grading systems, cooperative group trials, and novel management approaches. This review highlights the results of key clinical trials of CART for pediatric hematologic malignancies, discusses the most common toxicities seen to date, and elucidates challenges, opportunities, and areas of active research to optimize this therapy.

The expression pattern of Immune checkpoints after chemo/radiotherapy in the tumor microenvironment

As a disease with the highest disease-associated burden worldwide, cancer has been the main subject of a considerable proportion of medical research in recent years, intending to find more effective therapeutic approaches with fewer side effects. Combining conventional methods with newer biologically based treatments such as immunotherapy can be a promising approach to treating different tumors. The concept of "cancer immunoediting" that occurs in the field of the tumor microenvironment (TME) is the aspect of cancer therapy that has not been at the center of attention. One group of the role players of the so-called immunoediting process are the immune checkpoint molecules that exert either co-stimulatory or co-inhibitory effects in the anti-tumor immunity of the host. It involves alterations in a wide variety of immunologic pathways. Recent studies have proven that conventional cancer therapies, such as chemotherapy, radiotherapy, or a combination of them, i.e., chemoradiotherapy, alter the "immune compartment" of the TME. The mentioned changes encompass a wide range of variations, including the changes in the density and immunologic type of the tumor-infiltrating lymphocytes (TILs) and the alterations in the expression patterns of the different immune checkpoints. These rearrangements can have either anti-tumor immunity empowering or immune attenuating sequels. Thus, recognizing the consequences of various chemo(radio)therapeutic regimens in the TME seems to be of great significance in the evolution of therapeutic approaches. Therefore, the present review intends to summarize how chemo(radio)therapy affects the TME and specifically some of the most important, well-known immune checkpoints' expressions according to the recent studies in this field.

CAR T-Cell-Based gene therapy for cancers: new perspectives, challenges, and clinical developments

Chimeric antigen receptor (CAR)-T cell therapy is a progressive new pillar in immune cell therapy for cancer. It has yielded remarkable clinical responses in patients with B-cell leukemia or lymphoma. Unfortunately, many challenges remain to be addressed to overcome its ineffectiveness in the treatment of other hematological and solidtumor malignancies. The major hurdles of CAR T-cell therapy are the associated severe life-threatening toxicities such as cytokine release syndrome and limited anti-tumor efficacy. In this review, we briefly discuss cancer immunotherapy and the genetic engineering of T cells and, In detail, the current innovations in CAR T-cell strategies to improve efficacy in treating solid tumors and hematologic malignancies. Furthermore, we also discuss the current challenges in CAR T-cell therapy and new CAR T-cell-derived nanovesicle therapy. Finally, strategies to overcome the current clinical challenges associated with CAR T-cell therapy are included as well.

Progress and Prospect of Immunotherapy for Triple-Negative Breast Cancer

Breast cancer is the most commonly diagnosed cancer (estimated 2.3 million new cases in 2020) and the leading cause of cancer death (estimated 685,000 deaths in 2020) in women globally. Breast cancers have been categorized into four major molecular subtypes based on the immunohistochemistry (IHC) expression of classic hormone and growth factor receptors including the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), as well as a proliferation marker Ki-67 protein expression. Triple-negative breast cancer (TNBC), a breast cancer subtype lacking ER, PR, and HER2 expression, is associated with a high metastatic potential and poor prognosis. TNBC accounts for approximately only 15%–20% of new breast cancer diagnoses; it is responsible for most breast cancer–related deaths due to the lack of targeted treatment options for this patient population, and currently, systemic chemotherapy, radiation, and surgical excision remain the major treatment modalities for these patients with TNBC. Although breast cancer patients in general do not have a robust response to the immunotherapy, a subset of TNBC has been demonstrated to have high tumor mutation burden and high tumor-infiltrating lymphocytes, resembling the features observed on melanoma or lung cancers, which can benefit from the treatment of immune checkpoint inhibitors (ICIs). Therefore, the immunogenic nature of this aggressive disease has presented an opportunity for the development of TNBC-targeting immunotherapies. The recent US Food and Drug Administration approval of atezolizumab in combination with the chemotherapeutic agent nab-paclitaxel for the treatment of PD-L1-positive unresectable, locally advanced, or metastatic TNBC has led to a new era of immunotherapy in TNBC treatment. In addition, immunotherapy becomes an active research area, both in the cancer biology field and in the oncology field. In this review, we will extend our coverage on recent discoveries in preclinical research and early results in clinical trials from immune molecule-based therapy including cytokines, monoclonal antibodies, antibody–drug conjugates, bi-specific or tri-specific antibodies, ICIs, and neoantigen cancer vaccines; oncolytic virus-based therapies and adoptive immune cell transfer–based therapies including TIL, chimeric antigen receptor-T (CAR-T), CAR-NK, CAR-M, and T-cell receptor-T. In the end, we will list a series of the challenges and opportunities in immunotherapy prospectively and reveal novel technologies such as high-throughput single-cell sequencing and CRISPR gene editing-based screening to generate new knowledges of immunotherapy.

Treatment with Living Drugs: Pharmaceutical Aspects of CAR T Cells

BACKGROUND

Adoptive therapy with genetically modified T cells achieves spectacular remissions in advanced hematologic malignancies. In contrast to conventional drugs, this kind of therapy applies viable autologous T cells that are ex vivo genetically engineered with a chimeric antigen receptor (CAR) and are classified as advanced therapy medicinal products.

SUMMARY

As "living drugs," CAR T cells differ from classical pharmaceutical drugs as they provide a panel of cellular capacities upon CAR signaling, including the release of effector molecules and cytokines, redirected cytotoxicity, CAR T cell amplification, active migration, and long-term persistence and immunological memory. Here, we discuss pharmaceutical aspects, the regulatory requirements for CAR T cell manufacturing, and how CAR T cell pharmacokinetics are connected with the clinical outcome.

KEY MESSAGES

From the pharmacological perspective, the development of CAR T cells with high translational potential needs to address pharmacodynamic markers to balance safety and efficacy of CAR T cells and to address pharmacokinetics with respect to trafficking, homing, infiltration, and persistence of CAR T cells.

Programmed death‐ligand 1 expression on CD22‐specific chimeric antigen receptor‐modified T cells weakens antitumor potential

The molecules of programmed cell death protein‐1 (PD‐1) and ligand‐1 (PD‐L1) become new therapeutic targets for cancer therapy. Although tumor‐expressed PD‐L1 molecule is frequently dispensable for checkpoint blockade in some cancer patients, recent studies suggest that T cell‐expressed PD‐L1 molecule might play a crucial role in antitumor immunity. Here, to investigate CD22 chimeric antigen receptor (CAR)‐T cell therapy, we have generated the different CD22 CAR‐T constructs. We noticed that tumor cells induced PD‐L1 expression on the surface of CD22 CAR‐T cells. The induced PD‐L1 might limit immunogenic responses of CAR‐T cells. T cell‐expressed PD‐L1 leads to a suppressive signal by PD‐1/PD‐L1 engagement of CD22 CAR‐T cells. Meanwhile, PD‐L1 suppresses CD22 CAR‐T cell differentiation into memory T cells and negatively affected secretions of several essential cytokines, such as interleukin‐2 (IL‐2) and tumor necrosis factor (TNF)‐α. We further observed that anti‐PD‐L1 monoclonal antibodies rescued cytokine secretion of CD22 CAR‐T cells rather than anti‐PD‐1 monoclonal antibodies. Our current studies provide a potential mechanism to understand the functions and roles of T cell‐expressed PD‐L1 in tumor microenvironment. These results will encourage the physicians to re‐recognize the important roles of PD‐L1 in cancer immunotherapy studies and provide the helpful guidance for clinical operation of PD‐L1 inhibition drugs.

Induced CAR-Macrophages as a Novel Therapeutic Cell Type for Cancer Immune Cell Therapies

The Chimeric antigen receptor (CAR)-T cell therapy has made inroads in treating hematological malignancies. Nonetheless, there are still multiple hurdles in CAR-T cell therapy for solid tumors. Primary CAR-expressing macrophage cells (CAR-Ms) and induced pluripotent stem cells (iPSCs)-derived CAR-expressing macrophage cells (CAR-iMacs) have emerged as attractive alternatives in our quest for an efficient and inexpensive approach for tumor immune cell therapy. In this review, we list the current state of development of human CAR-macrophages and provide an overview of the crucial functions of human CAR-macrophages in the field of tumor immune cell therapy.

Evolving Strategies to Eliminate the CD4 T Cells HIV Viral Reservoir via CAR T Cell Immunotherapy

Although the advent of ART has significantly reduced the morbidity and mortality associated with HIV infection, the stable pool of HIV in latently infected cells requires lifelong treatment adherence, with the cessation of ART resulting in rapid reactivation of the virus and productive HIV infection. Therefore, these few cells containing replication-competent HIV, known as the latent HIV reservoir, act as the main barrier to immune clearance and HIV cure. While several strategies involving HIV silencing or its reactivation in latently infected cells for elimination by immune responses have been explored, exciting cell based immune therapies involving genetically engineered T cells expressing synthetic chimeric receptors (CAR T cells) are highly appealing and promising. CAR T cells, in contrast to endogenous cytotoxic T cells, can function independently of MHC to target HIV-infected cells, are efficacious and have demonstrated acceptable safety profiles and long-term persistence in peripheral blood. In this review, we present a comprehensive picture of the current efforts to target the HIV latent reservoir, with a focus on CAR T cell therapies. We highlight the current challenges and advances in this field, while discussing the importance of novel CAR designs in the efforts to find a HIV cure.

Role of Senescence in Tumorigenesis and Anticancer Therapy

Although the role of senescence in many physiological and pathological processes is becoming more identifiable, many aspects of senescence are still enigmatic. A special attention is paid to the role of this phenomenon in tumor development and therapy. This review mainly deals with a large spectrum of oncological issues, beginning with therapy-induced senescence and ending with oncogene-induced senescence. Moreover, the role of senescence in experimental approaches, such as primary cancer cell culture or reprogramming into stem cells, is also beginning to receive further consideration. Additional focus is made on senescence resulting from mitotic catastrophe processes triggered by events occurring during mitosis and jeopardizing chromosomal stability. It has to be also realized that based on recent findings, the basics of senescent cell property interpretation, such as irreversibility of proliferation blockade, can be undermined. It shows that the definition of senescence probably requires updating. Finally, the role of senescence is lately more understandable in the immune system, especially since senescence can diminish the effectiveness of the chimeric antigen receptor T-cell (CAR-T) therapy. In this review, we summarize the current knowledge regarding all these issues.