Tumor Antigen Escape from CAR T-cell Therapy

Overcoming antigen loss in CAR T therapy with Vγ9Vδ2 CAR T-cells

Background

Vγ9Vδ2 T-cells demonstrate potent antitumor activity in vitro but, despite successful safety studies, the clinical benefit of Vγ9Vδ2 in adoptive cell therapy has been limited. One approach to enhance the therapeutic potential of Vγ9Vδ2 T-cells while maintaining their safety profile is genetic engineering to express a chimeric antigen receptor (CAR). Vγ9Vδ2 CAR T-cells retain the ability to target tumor cells even after target antigen loss, a major cause of CAR treatment relapse.

Methods

Vγ9Vδ2 T-cells were expanded from peripheral blood mononuclear cells in the presence of high levels of interleukin 2 (IL-2) or IL-2 in combination with IL-15. Cells were then virally transduced with a CD19-directed CAR and underwent antigen-specific stimulation to enrich CAR-expressing cells.

Results

Vγ9Vδ2 CAR T-cells showed similar cytotoxic activity to conventional αβ-CAR T-cells against CD19-positive tumor cells. They demonstrated superior responses against CD19-negative tumor cells, however, particularly when IL-15 was included during expansion. This enhanced function was further confirmed in co-culture assays with mixed CD19-positive and CD19-negative tumor populations, simulating antigen loss.

Conclusions

Vγ9Vδ2 CAR T-cell therapy presents a promising strategy for B-cell malignancies, offering sustained antitumor activity even after antigen loss. This approach may help overcome a major limitation of conventional CAR T-cell therapy, potentially improving clinical outcomes.

The IAP antagonist tolinapant enhances the anti-tumor activity of cell therapies

Various gene-modified cell therapies have been investigated in clinical trials, among which chimeric antigen receptor (CAR)-T cell therapy has been approved for the treatment of B cell tumors and has shown remarkable therapeutic effects. However, challenges, such as, cancer recurrence and manufacturing issues remain. To overcome such limitations, we investigated whether combining CAR-T cells with tolinapant, an inhibitor of apoptosis proteins (IAP) antagonist with immunomodulatory activity, could enhance the anti-tumor effect. Tolinapant induced cancer cell death in the presence of TNF-α. Tumor killing by CAR-T, TCR-T or CÊNK cells was enhanced by tolinapant in vitro in a TNF-α-dependent manner. TNF-α secreted from CAR-T cells, in the presence of tolinapant, also induced cell death of antigen-negative cancer cells not in cell-cell contact with CAR-T cells. Addition of tolinapant potentiated efficacy of not only two different CAR-T, but also TCR-T and CAR-NK cells in vivo. Tolinapant treatment led to faster expansion of stimulated CAR-T cells in vitro and in vivo. Our study suggests that the combination of tolinapant improves the efficacy of cell-based cancer therapies by inducing both cancer cell death and CAR-T cell proliferation. This combination therapy may overcome the current limitations of cell-based therapies and enhance their anti-cancer effect.

Chimeric antigen receptor T cell immunotherapy for gynecological malignancies

Gynecologic malignancies pose a serious threat to women's health worldwide. Although immunotherapy has significantly revolutionized cancer treatment strategies, effective therapeutic options for recurrent or advanced gynecologic malignancies are still deficient, posing significant challenges to clinical therapy. Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable efficacy in treating hematologic malignancies, marking a significant change in the oncology treatment paradigm. However, despite the gradual increase in CAR T cell therapy used in treating solid tumors in recent years, its efficacy in treating gynecologic malignancies still needs further validation. This review will thoroughly examine CAR-T cell engineering and its mechanism of action on specific antigens associated with gynecologic malignancies, systematically assess the current application of CAR T cell therapy in gynecologic tumors and the advancements in clinical trials, and discuss the significant challenges and corresponding strategies, thereby offering a scientific foundation and guidance for future research in this area.

Unravelling the modified T cell receptor through Gen-Next CAR T cell therapy in Glioblastoma: Current status and future challenges

PURPOSE

Despite current technological advancements in the treatment of glioma, immediate alleviation of symptoms can be catered by therapeutic modalities, including surgery, chemotherapy, and combinatorial radiotherapy that exploit aberrations of glioma. Additionally, a small number of target antigens, their heterogeneity, and immune evasion are the potential reasons for developing targeted therapies. This oncologic milestone has catalyzed interest in developing immunotherapies against Glioblastoma to improve overall survival and cure patients with high-grade glioma. The next-gen CAR-T Cell therapy is one of the effective immunotherapeutic strategies in which autologous T cells have been modified to express receptors against GBM and it modulates cytotoxicity.

METHODS

In this review article, we examine preclinical and clinical outcomes, and limitations as well as present cutting-edge techniques to improve the function of CAR-T cell therapy and explore the possibility of combination therapy.

FINDINGS

To date, several CAR T-cell therapies are being evaluated in clinical trials for GBM and other brain malignancies and multiple preclinical studies have demonstrated encouraging outcomes.

IMPLICATIONS

CAR-T cell therapy represents a promising therapeutic paradigm in the treatment of solid tumors but a few limitations include, the blood-brain barrier (BBB), antigen escape, tumor microenvironment (TME), tumor heterogeneity, and its plasticity that suppresses immune responses weakens the ability of this therapy. Additional investigation is required that can accurately identify the targets and reflect the similar architecture of glioblastoma, thus optimizing the efficiency of CAR-T cell therapy; allowing for the selection of patients most likely to benefit from immuno-based treatments.

Novel humanized CD19-CAR-T (Now talicabtagene autoleucel, Tali-cel™) cells in relapsed/ refractory pediatric B-acute lymphoblastic leukemia- an open-label single-arm phase-I/Ib study

Chimeric Antigen Receptor-T (CAR-T) cell therapy is effective for relapsed/refractory B-acute lymphoblastic leukemia (r/r B-ALL) but is not universally available. We developed a novel humanized CD19-directed CAR-T (HCAR19) approved for Phase 1/1b/2 trials. Patients aged 3-25 years were enrolled with r/r B-ALL and ineligible for allogeneic stem cell transplant. Lymphodepletion utilized standard-dose fludarabine and cyclophosphamide. A 3 + 3 design testing 3 dose-ranges was used to determine Phase-2 Dose (P2D): Dose-A, 1 × 106 HCAR19 cells/kg, Dose-B, 3-5 × 106/kg, and Dose-C, 10-15 × 106/kg. Primary endpoint was overall response rate (ORR) at day-30 on bone-marrow flow-cytometry. From May-2021 to September-2023 12 patients [median age-14 (range: 5-24) years] were enrolled with median bone marrow blasts 19.5% at screening. Cytokine release syndrome occurred in 10 (83%) patients, predominantly Grades 1-2, and Grade-2 immune-cell associated neurotoxicity (ICANS) in 1. All patients had Grade-3 cytopenia. ORR was 91.7% (11/12), complete response (CR) in 8 (66.7%) and partial response in 3 (25%). Seven of 8 CRs were at Dose-levels B and C, all of which were sustained till 12 months follow-up. Patients who received dose levels below 3 × 106/kg, or did not achieve CR, had early loss of response or rapid progression. HCAR19 demonstrated safety, manageable toxicity, and durable remissions. and P2D was determined as 5-10 × 106 HCAR19-cells/kg. CLINICAL TRIAL REGISTRATION: The study is registered in the Clinical Trials Registry- India (CTRI/2021/05/033348 and CTRI/2023/03/050689).

The potential of chimeric antigen receptor -T cell therapy for endocrine cancer

Endocrine cancer, a relatively rare and heterogeneous tumor with diverse clinical features. The facile synthesis of hormones further complicates endocrine cancer treatment. Thus, the development of safe and effective systemic treatment approaches, such as chimeric antigen receptor (CAR) T cell therapy, is imperative to enhance the prognosis of patients with endocrine cancer. Although this therapy has achieved good results in the treatment of hematological malignancies, it encounters diverse complications and challenges in the context of endocrine cancer. This review delineates the generation of CAR-T cells, examines the potential of CAR-T cell therapy for endocrine cancer, enumerates pivotal antigens linked to endocrine cancer, encapsulates the challenges confronted with CAR-T cell therapy for endocrine cancer, and expounds upon strategies to overcome these limitations. The primary objective is to provide insightful perspectives that can contribute to the advancement of CAR-T cell therapy in the field of endocrine cancer.

DAP12-associated synthetic antigen receptors enable multi-targeting of T cells with independent chimeric receptors in a small genetic payload

We describe a series of DAP12-associated receptors that can be used to achieve multi-targeting within a small genetic payload. Empirical evaluation of scaffold/binder combinations is required to define the optimal synthetic receptor configuration. When two DAP12-associated synthetic receptors were expressed in T cells from a single vector, the surface levels of individual receptors was reduced when compared to T cells engineered with vectors that express a single receptor. The reduction in receptor expression had a pronounced effect on early, but not late, signaling events and primarily affected cytokine production. The functional deficiency was overcome by increasing synthetic receptor levels demonstrating that there is no fundamental issue related to co-expression of multiple DAP12-associated synthetic receptors in a single T cell. Our data show that T cells can be engineered with multiple recombinant DAP12-based receptors to yield multi-target specific T cells, however, thoughtful design and optimization are necessary.

Novel and effective tandem CD38 and CD19 targeting CAR-T cells inhibit hematological tumor immune escape

Targeting CD19 with chimeric antigen receptor (CAR)-T cells is clinically effective, but tumor immune escape and tumor recurrence still occur. Designing CAR-T cells that target multiple antigens simultaneously is a viable approach for inhibiting tumor immune escape, and promising findings have been reported. In this study, we designed new CD19 and CD38 dual-target CAR-T cells that are strongly cytotoxic to target cells expressing CD19 or CD38. In vitro studies, compared with single-target CAR-T cells or CD19/CD38 tandem (Tan) CAR-T cells, CD38/CD19 Tan CAR-T cells presented similar CAR expression, superior cytotoxicity and antigen-stimulated T-cell proliferation. In vivo studies, CD38/CD19 Tan CAR-T cells demonstrated the same efficacy and safety as single-target CAR-T. These CD19/CD38 Tan CAR-T cells are fully compatible with existing clinical-grade T-cell manufacturing procedures and can be implemented using current clinical protocols. In summary, our findings provide an effective solution to the challenge of tumor immune escape in anti-CD19 CAR-T-cell therapy.

Autologous T cell therapy for PRAME+ advanced solid tumors in HLA-A*02+ patients: a phase 1 trial

In contrast to chimeric antigen receptor T cells, T cell receptor (TCR)-engineered T cells can target intracellular tumor-associated antigens crucial for treating solid tumors. However, most trials published so far show limited clinical activity. Here we report interim data from a first-in-human, multicenter, open-label, 3 + 3 dose-escalation/de-escalation phase 1 trial studying IMA203, an autologous preferentially expressed antigen in melanoma (PRAME)-directed TCR T cell therapy in HLA-A*02+ patients with PRAME+ recurrent and/or refractory solid tumors, including melanoma and sarcoma. Primary objectives include the evaluation of safety and tolerability and the determination of the maximum tolerated dose (MTD) and/or recommended dose for extension. Secondary objectives include the evaluation of IMA203 TCR-engineered T cell persistence in peripheral blood, tumor response as well as duration of response. A total of 27 patients were enrolled in the phase 1a dose escalation and 13 patients in the phase 1b dose extension. IMA203 T cells were safe, and the MTD was not reached. Of the 41 patients receiving treatment (that is, who started lymphodepletion), severe cytokine release syndrome was observed in 4.9% (2/41), and severe neurotoxicity did not occur. In the 40 patients treated with IMA203, an overall response rate consisting of patients with unconfirmed or confirmed response (u/cORR) of 52.5% (21/40) and a cORR of 28.9% (11/38) was observed with a median duration of response of 4.4 months (range, 2.4-23.0, 95% confidence interval: 2.6-not reached) across multiple indications. Rapid T cell engraftment and long-term persistence of IMA203 T cells were observed. IMA203 T cells trafficked to all organs, and confirmed responses were more frequent in patients with higher dose. T cell exhaustion was not observed in the periphery; deep responses were enriched at higher PRAME expression; and higher T cell infiltration resulted in longer progression-free survival. Overall, IMA203 showed promising anti-tumor activity in multiple solid tumors, including refractory melanoma. ClinicalTrials.gov identifier: NCT03686124 .

NKG2D/CD28 chimeric receptor boosts cytotoxicity and durability of CAR-T cells for solid and hematological tumors

BACKGROUND

CAR-T cell therapy faces challenges in solid tumor treatment and hematologic malignancy relapse, among which the limited persistence of CAR-T cells and target antigen downregulation are prominent factors. Therefore, we engineered an NKG2D/CD28 chimeric co-stimulatory receptor (CCR), leveraging its broad ligand expression on tumors to enhance the antitumor activity of MSLN CAR and CD19 CAR-T cells.

METHODS

We generated MSLN CAR-T and CD19 CAR-T cells co-expressing the NKG2D/CD28 CCR and assessed their antitumor efficacy in vitro and in vivo. CAR-T cell activation, differentiation, and exhaustion were analyzed over time following tumor antigen stimulation. Furthermore, a chronic antigen stimulation model was established using tumor cells with low antigen density to simulate the sustained antigenic pressure encountered in vivo treatment conditions.

RESULTS

Our study shows that NKG2D/CD28&CAR-T cells exhibit enhanced cytotoxicity against tumor cells, especially those with low antigen density, both in vitro and in vivo. Compared to conventional second-generation MSLN CAR or CD19 CAR-T cells, these dual-targeted NKG2D/CD28&CAR-T cells demonstrate superior sensitivity in recognizing and lysing low-density antigen-expressing lung cancer and leukemia cells, and they are capable of eradicating tumors with low-density antigen expression in vivo. Furthermore, the complementary co-stimulation provided by the 4-1BB and CD28 intracellular domains in the CAR and NKG2D/CD28 promotes cytokine secretion, reduces CAR-T cell exhaustion, and enhances the in vivo persistence of CAR-T cells, significantly improving their antitumor efficacy.

CONCLUSION

The combination of CAR and NKG2D/CD28 offers a potent strategy to enhance the cytotoxicity and durability of CAR-T cells. This approach is promising for improving therapeutic outcomes in solid and hematological tumors and preventing recurrence in tumors with low target antigen density.

Advancements in immunotherapy for gastric cancer: Unveiling the potential of immune checkpoint inhibitors and emerging strategies

Gastric cancer (GC) is linked to high morbidity and mortality rates. Approximately two-thirds of GC patients are diagnosed at an advanced or metastatic stage. Conventional treatments for GC, including surgery, radiotherapy, and chemotherapy, offer limited prognostic improvement. Recently, immunotherapy has gained attention for its promising therapeutic effects in various tumors. Immunotherapy functions by activating and regulating the patient's immune cells to target and eliminate tumor cells, thereby reducing the tumor burden in the body. Among immunotherapies, immune checkpoint inhibitors (ICIs) are the most advanced. ICIs disrupt the inhibitory protein-small molecule (PD-L1, CTLA4, VISTA, TIM-3 and LAG3) interactions produced by immune cells, reactivating these cells to recognize and attack tumor cells. However, adverse reactions and resistance to ICIs hinder their further clinical and experimental development. Therefore, a comprehensive understanding of the advancements in ICIs for GC is crucial. This article discusses the latest developments in clinical trials of ICIs for GC and examines combination therapies involving ICIs (targeted therapy, chemotherapy, radiotherapy), alongside ongoing clinical trials. Additionally, the review investigates the tumor immune microenvironment and its role in non-responsiveness to ICIs, highlighting the function of tumor immune cells in ICI efficacy. Finally, the article explores the prospects and limitations of new immunotherapy-related technologies, such as tumor vaccines, nanotechnologies, and emerging therapeutic strategies, aiming to advance research into personalized and optimized immunotherapy for patients with locally advanced gastric cancer.

The development and potent antitumor efficacy of CD44/CD133 dual-targeting IL7Rα-armored CAR-T cells against glioblastoma

Tumor heterogeneity and an immunosuppressive microenvironment pose significant challenges for immunotherapy against solid tumors, particularly glioblastoma multiforme (GBM). Recent studies have highlighted the crucial role of glioma stem cells (GSCs) in tumor recurrence and therapeutic resistance. In this context, we developed a tandem chimeric antigen receptor (CAR)-T cell targeting CD44 and CD133 (PROM1), containing a truncated IL-7 receptor alpha intracellular domain (Δ7R) between the CD28 costimulatory receptor and the CD3ζ signaling chain (Tanζ-T28-Δ7R). Our target identification and validation were carried out using GSCs, samples from GBM patients, and the corresponding sequencing data. The antitumor efficacy of CAR-T cells was evaluated in patient-derived GSCs, intracranial xenograft models, patient-derived xenograft models, and glioblastoma organoids (GBOs). Single-cell RNA sequencing and mass cytometry were used to determine the immune phenotypes of CAR-T cells. We showed that locoregionally administered Tanζ-T28-Δ7R CAR-T cells induced long-term tumor regression with the desired safety outcomes. Patient-derived autologous Tanζ-T28-Δ7R CAR-T cells showed robust antitumor activity against GBOs. Our pre-clinical data has demonstrated the translational potential of Tanζ-T28-Δ7R CAR-T cell against GBM.

Transplantation of the MSLN-deficient Thymus Generates MSLN Epitope Reactive T Cells to Attenuate Tumor Progression

The development of mesothelin (MSLN) epitope reactive T cells is observed in mice that are immunized with the MSLN vaccine. Engineered T cells expressing MSLN-reactive high-affinity TCR exhibit extraordinary therapeutic effects for invasive pancreatic ductal adenocarcinoma in a mouse model. However, the generation of MSLN-reactive T cells through the introduction of MSLN-deficient thymus and the transplantation of the latter as a cure for cancer treatment have not been tested to date. In the present study, the expression of MSLN was mainly identified in medullary thymic epithelial cells (mTECs) but not in hematopoietic cells, cortical thymic epithelial cells (cTECs), endothelial cells, or fibroblast cells in the thymus. The increasement of activated T cells was observed in MSLN-expressing tumors from MSLN-deficient mice, indicating that MSLN-reactive T cells had developed. Finally, in an AOM-DSS-induced mouse model of colorectal cancer (CRC), transplantation of MSLN-deficient thymus repressed the progression of CRC, accompanied by an increased number of IFNγ-expressing T lymphocytes in the tumors. The data from this study demonstrated that ectopic transplantation of MSLN-deficient thymus induced MSLN-specific antitumor responses to MSLN-expressing tumors, and thus attenuated tumor progression.

Redirecting glucose flux during in vitro expansion generates epigenetically and metabolically superior T cells for cancer immunotherapy

Cellular therapies are living drugs whose efficacy depends on persistence and survival. Expansion of therapeutic T cells employs hypermetabolic culture conditions to promote T cell expansion. We show that typical in vitro expansion conditions generate metabolically and functionally impaired T cells more reliant on aerobic glycolysis than those expanding in vivo. We used dichloroacetate (DCA) to modulate glycolytic metabolism during expansion, resulting in elevated mitochondrial capacity, stemness, and improved antitumor efficacy in murine T cell receptor (TCR)-Tg and human CAR-T cells. DCA-conditioned T cells surprisingly show no elevated intratumoral effector function but rather have improved engraftment. DCA conditioning decreases reliance on glucose, promoting usage of serum-prevalent physiologic carbon sources. Further, DCA conditioning promotes metabolic flux from mitochondria to chromatin, resulting in increased histone acetylation at key longevity genes. Thus, hyperglycemic culture conditions promote expansion at the expense of metabolic flexibility and suggest pharmacologic metabolic rewiring as a beneficial strategy for improvement of cellular immunotherapies.

Natural killer cells: a new promising source for developing chimeric antigen receptor anti-cancer cells in hematological malignancies

In recent times, the application of CAR-T cell treatment has significantly progressed, showing auspicious treatment outcomes in hematologic malignancies. However, along with these advances, certain limitations and challenges hurdle the widespread utilization of this technology. Recently, CAR-NK cells have gained attention in cancer treatment, as this approach has an important advantage over CART therapy (i.e. no need for HLA matching) for targeting foreign cells. This review aims to explore the benefits of CAR NK cell therapy, and generation strategies, as well as the challenges and limitations hindering the application of CAR NK cells in experimental studies and trials on hematologic malignancies.

Current Landscape of Adoptive Cell Therapy and Challenge to Develop "Off-The-Shelf" Therapy for Hepatocellular Carcinoma

Adoptive cell therapy (ACT) is a type of immunotherapy in which autologous or allogeneic immune cells, such as tumor-infiltrating lymphocytes or engineered lymphocytes, are infused into patients with cancer to eliminate malignant cells. Recently, autologous T cells modified to express a chimeric antigen receptor (CAR) targeting CD19 showed a positive response in clinical studies for hematologic malignancies and have begun to be used in clinical practice. This article discusses the current status and promise of ACT research in hepatocellular carcinoma (HCC), focusing on challenges in off-the-shelf ACT using primary cells or induced pluripotent stem cells (iPSCs) with or without genetic engineering. Early clinical trials of autologous GPC-3-, MUC1-, or CEA-targeted CAR-T cell therapies are underway for HCC. There is a growing demand for the development of off-the-shelf therapies due to the high cost and manufacturing issues associated with autologous CAR-T. The development of ACT from various cell sources, such as NK cells, NKT cells, macrophages, and γδ T cells without MHC restriction other than T cells has been proposed. Advances in genome editing, including HLA gene knockout to avoid GvHD, and strategies to enhance efficacy in overcoming the suppressive tumor microenvironment, are used to create universal 'off-the-shelf' CAR-T cells which can be used immediately as therapeutic products from healthy donors or iPSC-derived immune cells. Despite several limitations, cell-based immunotherapy is expected to become a key cancer treatment modality for both hematologic malignancies and solid tumors including HCC, thanks to technological advancements overcoming these challenges.

Targeting cardiac fibrosis with Chimeric Antigen Receptor-Engineered Cells

Cardiac fibrosis poses a significant challenge in cardiovascular diseases due to its intricate pathogenesis, and there is currently no standardized and effective treatment approach. The fibrotic process entails the involvement of various cell types and molecular mechanisms, such as fibroblast activation and proliferation, increased collagen synthesis, and extracellular matrix rearrangement. Traditional therapies often fall short in efficacy or carry substantial side effects. However, recent studies have shown that Chimeric Antigen Receptor T (CAR-T) cells can selectively target and eliminate activated cardiac fibroblasts (CFs) in mice, leading to reduced cardiac fibrosis and improved myocardial tissue compliance. This breakthrough presents a new and promising avenue for treating cardiac fibrosis. Currently, CAR-T cell-based therapy for cardiac fibrosis is undergoing animal experimentation, indicating ample scope for enhancement. Future investigations could explore the application of CAR cell therapy in cardiac fibrosis treatment, including the potential of CAR-natural killer (CAR-NK) cells and CAR macrophages (CAR-M), offering novel insights and strategies for combating cardiac fibrosis.

Precision epitope editing: A path to advanced immunotherapies

The ability to recognize antigen epitope is crucial for generating an effective immune response. By engineering these epitopes, researchers can reduce on-target/off-tumor toxicity associated with targeted immunotherapy. Recent studies indicate that employing various gene editing tools to modify the epitopes of healthy hematopoietic stem and progenitor cells (HSPCs) can protect these cells from toxicity during tumor eradication, all while preserving their differentiation and function. This advancement greatly enhances the safety and efficacy of tumor immunotherapy.

Tonic signaling in CAR-T therapy: the lever long enough to move the planet

Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable efficacy in treating hematological malignancies and is expanding into other indications such as autoimmune diseases, fibrosis, aging and viral infection. However, clinical challenges persist in treating solid tumors, including physical barriers, tumor heterogeneity, poor in vivo persistence, and T-cell exhaustion, all of which hinder therapeutic efficacy. This review focuses on the critical role of tonic signaling in CAR-T therapy. Tonic signaling is a low-level constitutive signaling occurring in both natural and engineered antigen receptors without antigen stimulation. It plays a pivotal role in regulating immune cell homeostasis, exhaustion, persistence, and effector functions. The "Peak Theory" suggests an optimal level of tonic signaling for CAR-T function: while weak tonic signaling may result in poor proliferation and persistence, excessively strong signaling can cause T cell exhaustion. This review also summarizes the recent progress in mechanisms underlying the tonic signaling and strategies to fine-tune the CAR tonic signaling. By understanding and precisely modulating tonic signaling, the efficacy of CAR-T therapies can be further optimized, offering new avenues for treatment across a broader spectrum of diseases. These findings have implications beyond CAR-T cells, potentially impacting other engineered immune cell therapies such as CAR-NK and CAR-M.

Tumor Heterogeneity and the Immune Response in Non-Small Cell Lung Cancer: Emerging Insights and Implications for Immunotherapy

Resistance to immune checkpoint inhibitors (ICIs) represents a major challenge for the effective treatment of non-small cell lung cancer (NSCLC). Tumor heterogeneity has been identified as an important mechanism of treatment resistance in cancer and has been increasingly implicated in ICI resistance. The diversity and clonality of tumor neoantigens, which represent the target epitopes for tumor-specific immune cells, have been shown to impact the efficacy of immunotherapy. Advances in genomic techniques have further enhanced our understanding of clonal landscapes within NSCLC and their evolution in response to therapy. In this review, we examine the role of tumor heterogeneity during immune surveillance in NSCLC and highlight its spatial and temporal evolution as revealed by modern technologies. We explore additional sources of heterogeneity, including epigenetic and metabolic factors, that have come under greater scrutiny as potential mediators of the immune response. We finally discuss the implications of tumor heterogeneity on the efficacy of ICIs and highlight potential strategies for overcoming therapeutic resistance.

The T cell receptor landscape of childhood brain tumors

The diverse T cell receptor (TCR) repertoire confers the ability to recognize an almost unlimited array of antigens. Characterization of antigen specificity of tumor-infiltrating lymphocytes (TILs) is key for understanding antitumor immunity and for guiding the development of effective immunotherapies. Here, we report a large-scale comprehensive examination of the TCR landscape of TILs across the spectrum of pediatric brain tumors, the leading cause of cancer-related mortality in children. We show that a T cell clonality index can inform patient prognosis, where more clonality is associated with more favorable outcomes. Moreover, TCR similarity groups' assessment revealed patient clusters with defined human leukocyte antigen associations. Computational analysis of these clusters identified putative tumor antigens and peptides as targets for antitumor T cell immunity, which were functionally validated by T cell stimulation assays in vitro. Together, this study presents a framework for tumor antigen prediction based on in situ and in silico TIL TCR analyses. We propose that TCR-based investigations should inform tumor classification and precision immunotherapy development.

Multi-Targeting CAR-T Cell Strategies to Overcome Immune Evasion in Lymphoid and Myeloid Malignancies

BACKGROUND

Chimeric antigen receptor (CAR)-T cell therapy has become a groundbreaking treatment for hematological malignancies, particularly lymphomas and multiple myeloma, with high remission rates in refractory and relapsed patients. However, most CAR-T therapies target a single antigen, such as CD19, which can result in immune evasion through antigen escape. This mechanism describes the downregulation or complete loss of the targeted antigen by the tumor cells, eventually leading to relapse. To address this issue, multi-targeting strategies like logic-gated CARs, adapter CARs, or combination therapies can increase the potency of CAR-T cells. These approaches aim to minimize immune evasion by targeting multiple antigens simultaneously, thereby increasing treatment durability. Additionally, advanced tools such as next-generation sequencing (NGS), direct stochastic optical reconstruction microscopy (dSTORM), or multiparametric flow cytometry are helping to identify novel tumor-specific targets and improve therapy designs.

SUMMARY

This review explores the current landscape of CAR-T cell therapies in lymphoid and myeloid malignancies, highlights ongoing clinical trials, and discusses the future of these innovative multi-targeting approaches to improve patient outcome.

KEY MESSAGES

Antigen escape limits CAR-T cell therapy success, but multi-targeting strategies like logic gates and adapter CARs offer solutions. Optimizing antigen selection and CAR design, along with larger clinical trials, is essential for improving patient outcomes. Personalization using advanced technologies like CRISPR screening and single-cell RNA sequencing can enhance durability and effectiveness of treatments for heavily pretreated patients.

Targeting B7-H3 in solid tumors: Development and evaluation of novel CAR-T Cell therapy

Ovarian and gastric cancers, representative of many solid tumors, remain among the most challenging malignancies to treat due to limited therapeutic options and poor outcomes at advanced stages. Although immunotherapies have revolutionized cancer treatment, their efficacy in solid tumors has been hindered by issues such as antigen heterogeneity and the immunosuppressive tumor microenvironment. This study presents the development and evaluation of third-generation chimeric antigen receptor T (CAR-T) cells targeting B7-H3, an immune checkpoint molecule widely overexpressed in solid tumors. The B7-H3 CAR-T cells exhibited robust and selective cytotoxicity against B7-H3-positive tumor cells, sparing normal tissues. In preclinical animal models, these cells significantly inhibited tumor growth, demonstrating higher targeting specificity and preferential accumulation in tumor sites. These results highlight B7-H3-targeted CAR-T cells as a potential breakthrough in immunotherapy for solid tumors, offering a foundation for future clinical trials to refine their safety and efficacy.

A chimeric antigen receptor tailored to integrate complementary activation signals potentiates the antitumor activity of NK cells

BACKGROUND

Chimeric antigen receptors (CARs) are synthetic receptors that reprogram the target specificity and functions of CAR-expressing effector cells. The design of CAR constructs typically includes an extracellular antigen-binding moiety, hinge (H), transmembrane (TM), and intracellular signaling domains. Conventional CAR constructs are primarily designed for T cells but have been directly adopted for other effector cells, including natural killer (NK) cells, without tailored optimization. Given the benefits of CAR-NK cells over CAR-T cells in terms of safety, off-the-shelf utility, and antigen escape, there is an increasing emphasis on tailoring them to NK cell activation mechanisms.

METHODS

We first have taken a stepwise approach to modifying CAR components such as the combination and order of the H, TM, and signaling domains to achieve such tailoring in NK cells. Functionality of NK-tailored CARs were evaluated in vitro and in vivo in a model of CD19-expressing lymphoma, along with their expression and signaling properties in NK cells.

RESULTS

We found that NK-CAR driven by the synergistic combination of NK receptors NKG2D and 2B4 rather than DNAM-1 and 2B4 induces potent activation in NK cells. Further, more effective CAR-mediated cytotoxicity was observed following the sequential combination of DAP10, but not NKG2D TM, with 2B4 signaling domain despite the capacity of NKG2D TM to recruit endogenous DAP10 for signaling. Accordingly, an NK-CAR incorporating DAP10, 2B4, and CD3ζ signaling domains coupled to CD8α H and CD28 TM domains was identified as the most promising candidate to improve CAR-mediated cytotoxicity. This NK-tailored CAR provided more potent antitumor activity than a conventional T-CAR when delivered to NK cells both in vitro and in vivo.

CONCLUSIONS

Hence, NK receptor-based domains hold great promise for the future of NK-CAR design with potentially significant therapeutic benefits.

Bispecific antibody and chimeric antigen receptor (CAR) modified T-cell in the treatment of multiple myeloma: Where do we stand today?

Although the prognosis of patients with multiple myeloma (MM) has been significantly improved by the introduction of proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies, MM is still considered an incurable disease in the vast majority of the patients. In recent years, T-cell based immunotherapy represents a novel treatment strategy for relapsed/refractory (RR) MM. So far, chimeric antigen receptor (CAR) modified T-cells and bispecific T-cell engaging antibodies (bsAb) have shown promising anti-MM efficacy and manageable safety profile within clinical trials, and B-cell maturation antigen (BCMA) is the most commonly used immune target for T-cell based immunotherapies in MM. To date, several CAR T-cell and bsAb products have already been approved for the treatment of RRMM, leading to a paradigm shift in the MM therapy and providing a potential curative option. In this review, we provide a summary of mechanisms of action, immune targets, selected clinical data, resistance mechanisms and therapy sequencing of CAR T-cell and bsAb in MM.

Generation of allogeneic CAR-NKT cells from hematopoietic stem and progenitor cells using a clinically guided culture method

Cancer immunotherapy with autologous chimeric antigen receptor (CAR) T cells faces challenges in manufacturing and patient selection that could be avoided by using 'off-the-shelf' products, such as allogeneic CAR natural killer T (AlloCAR-NKT) cells. Previously, we reported a system for differentiating human hematopoietic stem and progenitor cells into AlloCAR-NKT cells, but the use of three-dimensional culture and xenogeneic feeders precluded its clinical application. Here we describe a clinically guided method to differentiate and expand IL-15-enhanced AlloCAR-NKT cells with high yield and purity. We generated AlloCAR-NKT cells targeting seven cancers and, in a multiple myeloma model, demonstrated their antitumor efficacy, expansion and persistence. The cells also selectively depleted immunosuppressive cells in the tumor microenviroment and antagonized tumor immune evasion via triple targeting of CAR, TCR and NK receptors. They exhibited a stable hypoimmunogenic phenotype associated with epigenetic and signaling regulation and did not induce detectable graft versus host disease or cytokine release syndrome. These properties of AlloCAR-NKT cells support their potential for clinical translation.

Personalized, autologous neoantigen-specific T cell therapy in metastatic melanoma: a phase 1 trial

New treatment approaches are warranted for patients with advanced melanoma refractory to immune checkpoint blockade (ICB) or BRAF-targeted therapy. We designed BNT221, a personalized, neoantigen-specific autologous T cell product derived from peripheral blood, and tested this in a 3 + 3 dose-finding study with two dose levels (DLs) in patients with locally advanced or metastatic melanoma, disease progression after ICB, measurable disease (Response Evaluation Criteria in Solid Tumors version 1.1) and, where appropriate, BRAF-targeted therapy. Primary and secondary objectives were evaluation of safety, highest tolerated dose and anti-tumor activity. We report here the non-pre-specified, final results of the completed monotherapy arm consisting of nine patients: three at DL1 (1 × 108-1 × 109 cells) and six at DL2 (2 × 109-1 × 1010 cells). Drug products (DPs) were generated for all enrolled patients. BNT221 was well tolerated across both DLs, with no dose-limiting toxicities of grade 3 or higher attributed to the T cell product observed. Specifically, no cytokine release, immune effector cell-associated neurotoxicity or macrophage activation syndromes were reported. A dose of 5.0 × 108-1.0 × 1010 cells was identified for further study conduct. Six patients showed stable disease as best overall response, and tumor reductions (≤20%) were reported for four of these patients. In exploratory analyses, multiple mutant-specific CD4+ and CD8+ T cell responses were generated in each DP. These were cytotoxic, polyfunctional and expressed T cell receptors with broad functional avidities. Neoantigen-specific clonotypes were detected after treatment in blood and tumor. Our results provide key insights into this neoantigen-specific adoptive T cell therapy and demonstrate proof of concept for this new therapeutic approach. ClinicalTrials.gov registration: NCT04625205 .

Tandem CAR-T cell therapy: recent advances and current challenges

CAR-T cell therapy has revolutionized cancer treatment. However, despite the achievements of this approach, there are still clinical challenges to address, such as antigen loss and the design of an optimal CAR structure. Multi-targeted CAR-T therapies, including tandem CAR-T cells, have emerged as a strategy to overcome some of these limitations and improve outcomes. Tandem CAR-T cells are currently being evaluated in preclinical and clinical studies for the treatment of hematological malignancies and solid tumors, showing promising results. These CARs have demonstrated efficacy, safety, and a relatively low relapse rate in these studies. Research suggests that TanCAR-T cells can enhance the outcomes and benefits of CAR-T cell therapy. However, challenges such as identifying the ideal CAR construct, selecting appropriate targets, and improving transduction efficiency remain unresolved, and further research is essential to address these limitations. This review highlights the potential of tandem CAR-T cells as a cancer treatment, summarizing preclinical and clinical studies with this innovative therapy and emphasizing the importance of continued research to overcome its limitations and improve its effectiveness.

Adopting tomorrow's therapies today: a perspective review of adoptive cell therapy in lung cancer

Lung cancer is the leading cause of all cancer-related deaths in the United States and remains a global health challenge. While targeted therapy has revolutionized the treatment landscape of nonsmall cell lung cancer, many patients lack actionable mutations. Immunotherapy, particularly immune checkpoint inhibitors (ICIs), have significantly impacted outcomes in lung cancer in the last decade. Some patients, however, never respond or become refractory to ICIs. Newer therapies aimed at augmenting the immune system and enhancing antitumor effects are currently being explored. Adoptive cell therapy (ACT) employs T cells isolated from either tumors or peripheral blood and often engineers them to effect antitumor immune response. Chimeric antigen receptor T (CAR-T) cell therapy, engineered T cell receptor therapy, and tumor-infiltrating lymphocytes are examples of adoptive cellular therapies. CAR-T cell therapy has been successful in the treatment of hematological malignancies with several CAR products gaining approval in the treatment of refractory blood cancers. The success of ACTs in hematological cancers has fueled research into the role of these therapies in solid cancers including lung cancer. Many trials have had early promising results, with many clinical trials currently enrolling. There are many limitations to the efficacy of ACTs, as well as risks and benefits with the individual subtypes of ACT. With growing knowledge about tumor antigens and more advanced cell engineering, there is potential for ACT to result in durable responses in immunologically "cold" tumors. Here, we review the major subtypes of ACTs, evidence supporting their use in lung cancer, challenges, and future perspectives in ACTs. Additionally, we include T cell engagers and mRNA vaccine studies and potential combinatorial strategies in lung cancer.

Overcoming chimeric antigen receptor-T (CAR-T) resistance with checkpoint inhibitors: Existing methods, challenges, clinical success, and future prospects : A comprehensive review

Immune checkpoint blockade is, as of today, the most successful form of cancer immunotherapy, with more than 43 % of cancer patients in the US eligible to receive it; however, only up to 12.5 % of patients respond to it. Similarly, adoptive cell therapy using bioengineered chimeric antigen receptorT (CAR-T) cells and T-cell receptor (TCR) cells has provided excellent responses against liquid tumours, but both forms of immunotherapy have encountered challenges within a tumour microenvironment that is both lacking in tumour-specific T-cells and is strongly immunosuppressive toward externally administered CAR-T and TCR cells. This review focuses on understanding approved checkpoint blockade and adoptive cell therapy at both biological and clinical levels before delving into how and why their combination holds significant promise in overcoming their individual shortcomings. The advent of next-generation checkpoint inhibitors has further strengthened the immune checkpoint field, and a special section explores how these inhibitors can address existing hurdles in combining checkpoint blockade with adoptive cell therapy and homing in on our cancer target for long-term immunity.

CV1-secreting sCAR-T cells potentiate the abscopal effect of microwave ablation in heterogeneous tumors

Microwave ablation (MWA) triggers a weak systemic immune response that leads to the abscopal regression of distant metastases while killing local tumors, known as the abscopal effect. Combining MWA with chimeric antigen receptor (CAR)-T cells demonstrates promise in enhancing the abscopal effect in antigen-homogeneous tumors. However, the loss of the antigen recognized by CAR or intrinsic antigenic heterogeneity in solid tumors poses a major obstacle. SIRPα variant (CV1)-secreting CAR-T (sCAR-T) cells elicit an abscopal effect on distant tumors with antigen heterogeneity in mice receiving local MWA. Mechanistically, sCAR-T cells can locally eliminate antigen-positive tumors and secrete CV1, whereas the secreted CV1 can activate macrophages that migrate to non-ablated tumor sites in response to post-MWA chemokines, eliciting a macrophage-dependent abscopal effect that enables phagocytosis of antigen-heterogeneous cancer cells. This macrophage-dependent abscopal effect instigated by MWA and sCAR-T cells offers a clinically translatable strategy in metastatic solid tumors with antigen heterogeneity.

Use of a universal targeting CAR T cell to simultaneously kill cancer cells and cancer-associated fibroblasts

CAR T cells therapies have demonstrated success in treating hematologic malignancies, but have proven less effective in eradicating solid tumors. While suppressive immune cells may contribute to reduced CAR T cell efficacies in malignant masses, cancer-associated fibroblasts (CAFs) are also believed to facilitate tumor survival by secreting growth factors, immunosuppressive cytokines, and extracellular matrix components that inhibit drug and immune cell filtration and facilitate metastasis. In an effort to eliminate both CAFs and cancer cells simultaneously, we have employed a universal CAR T cell that can attack both cell types when supplemented with appropriate bispecific adapters. We show here that tumor regression is indeed enhanced when CAR T cells are directed to concurrently kill both cancer cells and CAFs. We further demonstrate that simultaneous targeting of both cell types enhances CAR T cell proliferation, activation, tumor infiltration, and tumor distribution relative to targeting only a single cell type. Because all of these benefits are achieved in both cold and hot tumors without significant toxicity, we conclude that use of a universal CAR T cell in combination with multiple bispecific adapters can provide a safe, potent, cost-effective, and scalable alternative to the treatment of solid tumors with conventional CAR T cells.

Targeting HLA-E-overexpressing cancers with a NKG2A/C switch receptor

BACKGROUND

Human leukocyte antigen (HLA)-E is overexpressed by a large proportion of solid tumors, including malignant glioblastoma, and acts as a major checkpoint for NKG2A+ CD8+ T cells and natural killer (NK) cells in the tumor microenvironment and circulation. This axis operates alongside PD-L1 to inhibit effector responses by T and NK cells.

METHODS

We engineered a chimeric A/C switch receptor, combining the high HLA-E binding affinity of the NKG2A receptor ectodomain with the activating signaling of the NKG2C receptor endodomain. The cytotoxic function of A/C switch-transduced NK and T cells was evaluated against tumor cells with varying levels of HLA-E expression. In vivo efficacy was assessed using a xenograft model of glioblastoma.

FINDINGS

A/C switch-transduced NK and T cells exhibited superior and specific cytotoxicity against tumor cells with medium to high HLA-E expression. A/C switch-expressing human T cells demonstrated enhanced anti-tumor function in a glioblastoma xenograft model. The activity of the modified T cells was governed by an equilibrium between A/C switch levels and HLA-E expression, creating a therapeutic window to minimize on-target, off-tumor toxicities. Normal cells remained insensitive to A/C switch T cells, even after interferon (IFN)-γ pretreatment to induce HLA-E expression.

CONCLUSIONS

The A/C switch receptor effectively targets tumor cells expressing high levels of HLA-E, either alone or in combination with other engineered specificities, to overcome the suppressive NKG2A/HLA-E checkpoint. This approach offers a promising therapeutic strategy with a favorable safety profile for targeting HLA-E-overexpressing tumors.

FUNDING

This work was funded by The Research Council of Norway, the Norwegian Cancer Society, and the National Cancer Institute.

Spatial Control of CAR T Cell Activation Using Tumor-Homing Polymers

CAR T cell therapies often lack specificity, leading to issues ranging from inadequate antigen targeting to off-tumor toxicities. To counter that lack of specificity, we expanded tumor targeting capabilities with universal CAR and spatially defined CAR T cell engagement with targets through a combination of synthetic biology and biomaterial approaches. We developed a novel framework, called "In situ Mobilization: Polymer Activated Cell Therapies" (IMPACT) for polymer-mediated, anatomical control of IF-THEN gated CAR T cells. With IMPACT, a regulated payload such as a BiTE or tumor-targeting CAR will only be expressed after engineered cells engage a tumor-localizing polymer ("IF" condition). In this first demonstration of IMPACT, we engineered CAR T cells to respond to fluorescein that is displayed by an injectable polymer that binds to and is retained in fibrin deposits in tumor microenvironments. This interaction then drives selective and conditional expression of a protein within tumors ("THEN" condition). Here, we develop the polymer and CAR T cell infrastructure of IMPACT and demonstrate tumor-localized CAR T cell activation in a murine tumor model after the intravenous administration of polymer and engineered T cells.

Gp350-targeted CAR-T therapy in EBV-positive Burkitt lymphoma: pre-clinical development of gp350 CAR-T

BACKGROUND

Epstein-Barr virus (EBV) is an oncovirus belonging to the herpesvirus family, associated with the pathogenesis of multiple malignancies, particularly Burkitt lymphoma (BL). The virus remains latent in host cells and plays a critical role in tumor progression through various mechanisms. A key glycoprotein, gp350, expressed during the lytic phase of EBV, is instrumental in viral entry into B cells and presents a unique antigenic target, making it a promising candidate for immunotherapeutic approaches, such as chimeric antigen receptor T-cell (CAR-T) therapy.

METHODS

In this study, we engineered CAR-T cells targeted against the gp350 glycoprotein and assessed their therapeutic potential through a series of in vitro and in vivo experiments. The efficacy of the gp350-CAR-T cells was evaluated by comparing their cytotoxic effects against both EBV-positive and -negative tumor cell lines. We utilized a xenograft model of Burkitt lymphoma to monitor the impact of gp350-CAR-T cell administration on tumor progression and overall survival.

RESULTS

The engineered gp350-CAR-T cells demonstrated potent cytotoxicity specifically against EBV-positive tumor cell lines. In our in vivo xenograft model, administration of gp350-CAR-T cells resulted in significant inhibition of tumor growth, highlighting their capability to effectively target and eliminate EBV-positive lymphomas. This selectivity underscores the potential of utilizing gp350 as a specific target for immunotherapy.

CONCLUSION

Our findings advocate for the clinical application of gp350-directed CAR-T therapy as a prospective treatment strategy for patients with relapsed or refractory EBV-positive tumors. Given the encouraging preclinical results, further research is warranted to optimize CAR-T cell production processes and extend the potential of this therapy to other EBV-associated malignancies, paving the way for improved outcomes in affected patient populations.

Enhancing CAR T-Cell Function with Domains of Innate Immunity Sensors

The innate immune system plays an important role in protecting the organism via recognizing the danger signals and pathogens through pattern recognition receptors. By sensing the danger signal and conveying the signaling towards the elimination of the threat, several families of these receptors, expressed on different myeloid and innate lymphoid cells, serve as the first defense line in the innate immunity. Toll-like receptors, C-type lectin receptors, and many other receptors therefore illustrate the importance of the protective role of the immune system. This was additionally confirmed by CAR T-cell-based cancer immunotherapy, where the patient's own immune system is being used for successful tumor elimination. CAR T-cells have proven themselves to be a potent therapeutic option, yet in some cases their efficiency could be enhanced. Innate immune sensors that include strong activation and signaling domains, for instance, part of the Toll-like receptors, MyD88 (Myeloid Differentiation Primary Response gene), NKG2D (Natural killer group 2-member D), and many other domains, could be used as a CAR building module to increase the functionality and potency of the CAR T-cells.

Reconfiguring the immune system to target cancer: Therapies based on T cells, cytokines, and vaccines

Over the years, extensive research has been dedicated to performing in-depth analysis of cancer to uncover the intricate details of its nature - including the types of cancer, causative agents, stimulators of disease progression, factors contributing to poor prognosis, and efficient therapies to restrict the metastatic aggressiveness. This chapter highlights the mechanisms through which different arms of the host immune system - namely cytokines, lymphocytes, antigen-presenting cells (APCs) -can be mobilized to eradicate cancer. Most malignant tumors are either poorly immunogenic, or are harbored in a highly immuno-suppressive microenvironment. This is why reinforcing the host's anti-tumor defenses, through infusion of pro-inflammatory cytokines, tumor antigen-loaded APCs, and anti-tumor cytotoxic cells has emerged as a viable treatment option against cancer. The chapter also highlights the ongoing preclinical and clinical studies in different malignancies and the outcome of various therapies. Although these methods are not foolproof, and antigen escape variants can still evade or develop resistance to customized therapies, they achieve disease stabilization in several cases when conventional treatments fail. In many instances, combination therapies involving cytokines, T cells, and vaccinations prove more effective than monotherapies. The limitations of the current therapies are also discussed, along with ongoing modifications aimed at improving efficacy.

Advances in engineered T cell immunotherapy for autoimmune and other non-oncological diseases

Adoptive immunotherapy using engineered T cells expressing chimeric antigen receptors has shown remarkable success in treating patients with hematological malignancies. However, realizing broader therapeutic applications of engineered T cells in other diseases requires further exploration in clinical investigations. In this review, we highlight recent advances in the engineering of T cells in non-oncology areas, including autoimmune and inflammatory diseases, infections, fibrosis, hemophilia, and aging. Chimeric antigen receptor immunotherapy has shown good outcomes in non-oncology areas, but many challenges remain in improving its safety and efficacy and and expanding its application to the treatment of non-oncological diseases.

TBK1 Targeting Is Identified as a Therapeutic Strategy to Enhance CAR T-Cell Efficacy Using Patient-Derived Organotypic Tumor Spheroids

Novel therapeutic strategies are needed to improve the efficacy of chimeric antigen receptor (CAR) T cells as a treatment of solid tumors. Multiple tumor microenvironmental factors are thought to contribute to resistance to CAR T-cell therapy in solid tumors, and appropriate model systems to identify and examine these factors using clinically relevant biospecimens are limited. In this study, we examined the activity of B7-H3-directed CAR T cells (B7-H3.CAR-T) using 3D microfluidic cultures of patient-derived organotypic tumor spheroids (PDOTS) and then confirmed the activity of B7-H3.CAR T cells in PDOTS. Although B7-H3 expression in PDOTS was associated with B7-H3.CAR-T sensitivity, mechanistic studies revealed dynamic upregulation of co-inhibitory receptors on CAR T-cells following target cell encounter that led to CAR T-cell dysfunction and limited efficacy against B7-H3-expressing tumors. PD-1 blockade restored CAR T-cell activity in monotypic and organotypic tumor spheroids with improved tumor control and upregulation of effector cytokines. Given the emerging role of TANK-binding kinase 1 (TBK1) as an immune evasion gene, we examined the effect of TBK1 inhibition on CAR T-cell efficacy. Similar to PD-1 blockade, TBK1 inhibition restored CAR T-cell activity in monotypic and organotypic tumor spheroids, prevented CAR T-cell dysfunction, and enhanced CAR T-cell proliferation. Inhibition or deletion of TBK1 also enhanced the sensitivity of cancer cells to immune-mediated killing. Taken together, our results demonstrate the feasibility and utility of ex vivo profiling of CAR T cells using PDOTS and suggest that targeting TBK1 could be used to enhance CAR T-cell efficacy by overcoming tumor-intrinsic and -extrinsic resistance mechanisms.

CAR-T cell therapy in the treatment of relapsed or refractory primary central nervous system lymphoma: recent advances and challenges

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive lymphoma that is isolated in the central nervous system (CNS) or vitreoretinal space. High-dose methotrexate (HD-MTX)-based immunochemotherapy is the frontline for its treatment, with a high early response rate. However, relapsed or refractory (R/R) patients present numerous difficulties and challenges in clinical treatment. Chimeric antigen receptor (CAR)-T cells offer a promising option for the treatment of hematologic malignancies, especially in the R/R B-cell lymphoma and multiple myeloma. Despite the exclusion of most PCNSL cases from pivotal CAR-T cell trials due to their specific tumor microenvironment (TME), available preclinical and clinical studies with small cohorts suggest an overall acceptable safety profile and remarkable anti-tumor effects. In this review, we will provide the development process of CAR-T cells and summarize the research progress, limitations, and future perspectives of CAR-T cell therapy in patients with R/R PCNSL.

Trogocytosis-mediated immune evasion in the tumor microenvironment

Trogocytosis is a dynamic cellular process characterized by the exchange of the plasma membrane and associated cytosol during cell-to-cell interactions. Unlike phagocytosis, this transfer maintains the surface localization of transferred membrane molecules. For example, CD4 T cells engaging with antigen-presenting cells undergo trogocytosis, which facilitates the transfer of antigen-loaded major histocompatibility complex (MHC) class II molecules from antigen-presenting cells to CD4 T cells. This transfer results in the formation of antigen-loaded MHC class II molecule-dressed CD4 T cells. These "dressed" CD4 T cells subsequently participate in antigen presentation to other CD4 T cells. Additionally, trogocytosis enables the acquisition of immune-regulatory molecules, such as CTLA-4 and Tim3, in recipient cells, thereby modulating their anti-tumor immunity. Concurrently, donor cells undergo plasma membrane loss, and substantial loss can trigger trogocytosis-mediated cell death, termed trogoptosis. This review aims to explore the trogocytosis-mediated transfer of immune regulatory molecules and their implications within the tumor microenvironment to elucidate the underlying mechanisms of immune evasion in cancers.

Targeting BCMA in multiple myeloma: designs, challenges, and future directions

Chimeric antigen receptor (CAR) T cell therapy has emerged as a groundbreaking immunotherapy, demonstrating significant efficacy in treating B cell malignancies. In the context of multiple myeloma (MM), B cell maturation antigen (BCMA) has been identified as a critical target, driving the development of CAR T cell therapies designed to address this plasma cell cancer. Various CAR designs, utilizing different BCMA recognition domains, have yielded promising clinical results, leading to the approval of two BCMA-targeting CAR T cell therapies by the US Food and Drug Administration (FDA) for the treatment of MM. This review uniquely examines the BCMA CAR T cell landscape, emphasizing the design of recognition domains, clinical efficacy, and patient outcomes. It critically addresses emerging challenges such as antigen escape and toxicity profiles, which have surfaced alongside therapeutic advances. Moreover, the review spotlights cutting-edge developments, including dual-targeting CAR T strategies, advancements in CAR T cell manufacturing, and innovative allogeneic CAR T approaches utilizing healthy donor cells. By detailing both the breakthroughs and ongoing challenges in BCMA CAR T cell therapy, this review offers a comprehensive perspective on the current state and future possibilities of CAR T cell therapy for MM and its expanding role in treating hematologic malignancies and beyond.

Adoptive cell therapy in acute myeloid leukemia: the current landscape and emerging strategies

Efforts to produce adoptive cell therapies in AML have been largely unfruitful, despite the success seen in lymphoid malignancies. Identifying targetable antigens on leukemic cells that are absent on normal progenitor cells remains a major obstacle, as is the hostile tumor microenvironment created by AML blasts. In this review, we summarize the challenges in the development of adoptive cell therapies such as CAR-T, CAR-NK, and TCR-T cells in AML, discussing both autologous and allogeneic therapies. We also discuss methods to address myelotoxicity associated with these therapies, including rapidly switchable CAR platforms and CRISPR-Cas9 genetic engineering of hematopoietic stem cells. Finally, we present the current clinical landscape in these areas, along with future directions in the field.

Current status and perspectives of clinical trials for tumor-infiltrating lymphocyte therapy

Immunotherapies, mainly immune checkpoint inhibitors (ICIs), have revolutionized cancer treatment strategies over the past decade, but their limitations have limited clinical applications. Tumor-infiltrating lymphocyte (TIL) therapy is a type of adoptive cell therapy (ACT), which collects infiltrating lymphocytes at the tumor site and expands them in vitro to obtain TIL final products cloned by various T-cell receptors, subsequently reinfused TIL into the patient, which is effective for the treatment of solid tumors. The approval of Lifileucel for commercialization marks the success of TIL therapy. This review summarizes the current status of clinical trials of TIL treatment. In addition, it is suggested that the current research trend of TIL should focus on improving the survival time of TIL in vivo, reducing drug toxicity, and searching for prognostic markers. Finally, it is expected that TIL therapy can be applied to a more wide range of clinical treatments.

Low-dose SAHA enhances CD8+ T cell-mediated antitumor immunity by boosting MHC I expression in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is a highly aggressive type of lung cancer with poor responses to traditional therapies such as surgery, radiotherapy, and chemotherapy. While immunotherapy has become an effective approach for treating multiple types of cancer, solid tumors frequently exhibit immune escape through various mechanisms, including downregulation of MHC I expression. However, whether the upregulation of MHC I expression can improve the immunotherapeutic effect on NSCLC remains unexplored. Suberoylanilide hydroxamic acid (SAHA) is a potent histone deacetylase (HDAC) inhibitor that has been applied clinically to treat lymphoma, but a high dose of SAHA kills tumor cells and normal cells without preference. Here, we report that low-dose SAHA enhances CD8+ T cell-mediated antitumor immunity by upregulating MHC I expression in NSCLC cells.

METHODS

Flow cytometric analysis, quantitative real-time PCR and western blot were used to analyze the expression of MHC I, STAT1 and Smad2/3 in both human and mouse NSCLC cell lines after SAHA treatment. The nuclear translocation of phosphorylated STAT1 and Smad2/3 was investigated by western blot and immunofluorescence staining. The mechanisms underlying STAT1 and Smad2/3 upregulation were analyzed through database searches and chromatin immunoprecipitation-qPCR. Finally, we assessed the antitumor effect of specific CD8+ T cells with SAHA treatment in vivo and in vitro.

RESULTS

We showed that low-dose SAHA upregulated the expression of MHC I in NSCLC cell lines without affecting cell viability. We also provided evidence that high levels of MHC I induced by SAHA promoted the activation, proliferation, and cytotoxicity of specific CD8+ T cells in mouse models. Mechanistically, low-dose SAHA increased the levels of H3K9ac and H3K27ac in the promoters of the STAT1, Smad2 and Smad3 genes in NSCLC cells by inhibiting HDAC activity, resulting in elevated expression levels of STAT1, Smad2 and Smad3. The nuclear translocation of phosphorylated STAT1 and Smad2/3 markedly upregulated the expression of MHC I in NSCLC cells.

CONCLUSIONS

Low-dose SAHA enhances CD8+ T cell-mediated antitumor immunity by boosting MHC I expression in NSCLC cells. Thus, we revealed a key mechanism of SAHA-mediated enhanced antitumor immunity, providing insights into a novel immunotherapy strategy for NSCLC.

The Role and Challenges of Investigator-Initiated Trials in the Cell and Gene Therapy Products Boom in Mainland China

As cutting-edge technologies in biomedicine, cell and gene therapy (CGT) products demonstrate immense potential in treating cancer, rare diseases, and genetic disorders, thereby driving the importance of clinical research in this area. This study analyzes the growth trends and key characteristics of 1033 Investigator-Initiated Trials (IITs) conducted by mainland Chinese institutions in the CGT field. The results show that IITs have played a positive role in the early proof-of-concept of CGT products, helping to obtain preliminary safety and efficacy data, and exploring the combination of CGT products with other therapies. Additionally, this study discusses the regional distribution, therapeutic areas, and challenges faced by IITs in the development of CGT products in China. Based on these findings, policy suggestions are proposed to optimize the regulation of IITs in mainland China, such as improving regulatory frameworks and enhancing technical guidance. It is hoped that these measures will further improve the efficiency and quality of IITs, fully utilize the large patient base and abundant clinical resources, and support the development of high-quality CGT products in mainland China.

Clinical progress in the development of CAR T cells to treat malignant glioma

CONTEXT

Chimeric antigen receptor (CAR) T cell therapy is an exciting modality of immunotherapy that has revolutionized the treatment of hematologic malignancies. However, translating this success to malignant gliomas such as glioblastoma (GBM) and diffuse midline glioma (DMG) remains a formidable challenge due to multiple biologic, anatomic, and immunologic factors. Despite these hurdles, a number of clinical trials deployed over the last decade have increased optimism for the potential of CAR T cell therapy in glioma treatment.

EVIDENCE SYNTHESIS

We highlight historical and ongoing clinical trials of CAR T cell therapy in glioma, with a focus on key tumor-associated antigens such as IL-13Rα2, HER2, EGFR, EGFRvIII, EphA2, GD2, and B7-H3. Early studies established proof-of-concept for antigen-specific CAR T cell targeting, yet immune evasion mechanisms such as antigen downregulation and limited CAR T cell persistence remain significant obstacles. Recent approaches, including multiantigen targeting, alternative cell sources, and innovations in delivery routes offer promising strategies to overcome these challenges.

CONCLUSIONS

The rapid evolution of investigational CAR T cell therapies portends great potential for the future of glioma treatment. Future studies will need to refine antigen targeting strategies, optimize CAR T cell persistence, and integrate combinatorial approaches to fully harness the therapeutic potential of this modality and improve the therapeutic window against brain tumors.

The molecular receptor NKBB enhances the persistence and anti-hepatocellular carcinoma activity of GPC3 CAR-T cells

Chimeric antigen receptor (CAR) T cells have encouraging results in the treatment of hematological malignancies. However, CAR-T therapy still faces numerous challenges against solid tumors, such as hepatocellular carcinoma (HCC), owing to heterogeneous antigen expression in tumor cells, limited persistence of CAR-T cells, etc. Therefore, to treat HCC more effectively, we connected the molecular receptor NKBB to a second-generation glypican-3 (GPC3) CAR to construct GC3328z-NKBB CAR-T cells, which have double specific targets of GPC3 and NKG2DLs (natural killer group 2, member D ligands), dual co-stimulation of CD28 and 41BB, and a single CD3ζ chain. Our study showed that the molecular receptor NKBB conferred GPC3 CAR-T cells with enhanced migration and infiltration abilities towards HCC, higher central memory T (TCM) cell proportion and proliferation capacity, and reduced exhaustion level. GC3328z-NKBB CAR-T cells exhibited improved cytotoxicity against HCC cells and prolonged persistence. The cathepsin L/interleukin-17 (CTSL/IL-17) axis contributed to the superior anti-HCC activity of GC3328z-NKBB CAR-T cells. Overall, the molecular receptor NKBB significantly increased the persistence of GPC3 CAR-T cells, and GC3328z-NKBB CAR-T cells possessed potent anti-HCC activity in mice, providing a new strategy for the potential improvement of adoptive T cell therapy in the treatment of HCC.

Boosting CAR-T cell therapy through vaccine synergy

Chimeric antigen receptor (CAR)-T cell therapy has transformed the treatment landscape for hematological cancers. However, achieving comparable success in solid tumors remains challenging. Factors contributing to these limitations include the scarcity of tumor-specific antigens (TSAs), insufficient CAR-T cell infiltration, and the immunosuppressive tumor microenvironment (TME). Vaccine-based strategies are emerging as potential approaches to address these challenges, enhancing CAR-T cell expansion, persistence, and antitumor efficacy. In this review, we explore diverse vaccine modalities, including mRNA, peptide, viral vector, and dendritic cell (DC)-based vaccines, and their roles in augmenting CAR-T cell responses. Special focus is given to recent clinical advancements combining mRNA-based vaccines with CAR-T therapy for the treatment of genitourinary cancers. In addition, we discuss crucial considerations for optimizing vaccine dosing, scheduling, and delivery to maximize CAR-T synergy, aiming to refine this combination strategy to improve treatment efficacy and safety.