Treatment of metastatic renal cell carcinoma with CAIX CAR-engineered T cells: clinical evaluation and management of on-target toxicity

Carbonic anhydrase IX: An atypical target for innovative therapies in cancer

Carbonic anhydrases (CAs), are metallo-enzymes implicated in several pathophysiological processes where tissue pH regulation is required. CA IX is a tumor-associated CA isoform induced by hypoxia and involved in the adaptation of tumor cells to acidosis. Indeed, several tumor-driving pathways can induce CA IX expression, and this in turn has been associated to cancer cells invasion and metastatic features as well as to induction of stem-like features, drug resistance and recurrence. After its functional and structural characterization CA IX targeting approaches have been developed to inhibit its activity in neoplastic tissues, and to date this field has seen an incredible acceleration in terms of therapeutic options and biological readouts. Small molecules inhibitors, hybrid/dual targeting drugs, targeting antibodies and adoptive (CAR-T based) cell therapy have been developed at preclinical level, whereas a sulfonamide CA IX inhibitor and an antibody entered Phase Ib/II clinical trials for the treatment and imaging of different solid tumors. Here recent advances on CA IX biology and pharmacology in cancer, and its therapeutic targeting will be discussed.

Receptor tyrosine kinase-like orphan receptor 1: A novel antitumor target in gastrointestinal cancers

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a member of the type I receptor tyrosine kinase family. ROR1 is pivotal in embryonic development and cancer, and serves as a biomarker and therapeutic target. It has soluble and membrane-bound subtypes, with the latter highly expressed in tumors. ROR1 is conserved throughout evolution and may play a role in the development of gastrointestinal cancer through multiple signaling pathways and molecular mechanisms. Studies suggest that overexpression of ROR1 may increase tumor invasiveness and metastasis. Additionally, ROR1 may regulate the cell cycle, stem cell characteristics, and interact with other signaling pathways to affect cancer progression. This review explores the structure, expression and role of ROR1 in the development of gastrointestinal cancers. It discusses current antitumor strategies, outlining challenges and prospects for treatment.

Targeting apoptosis in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most prevalent subtype of renal cancer, accounting for approximately 80% of all renal cell cancers. Due to its exceptional inter- and intratumor heterogeneity, it is highly resistant to conventional systemic therapies. Targeting the evasion of cell death, one of cancer's hallmarks, is currently emerging as an alternative strategy for ccRCC. In this article, we review the current state of apoptosis-inducing therapies against ccRCC, including antisense oligonucleotides, BH3 mimetics, histone deacetylase inhibitors, cyclin-kinase inhibitors, inhibitors of apoptosis protein antagonists, and monoclonal antibodies. Although preclinical studies have shown encouraging results, these compounds fail to improve patients' outcomes significantly. Current evidence suggests that inducing apoptosis in ccRCC may promote tumor progression through apoptosis-induced proliferation, anastasis, and apoptosis-induced nuclear expulsion. Therefore, re-evaluating this approach is expected to enable successful preclinical-to-clinical translation.

Challenges and strategies in relation to effective CAR-T cell immunotherapy for solid tumors

Chimeric Antigen Receptor T cell (CAR-T) therapy has revolutionized cancer treatment, but its application to solid tumors is limited. CAR-T cells have poor incapability of entering, surviving, proliferating, and finally exerting function in the tumor microenvironment. This review summarizes the main strategies related to enhancing the infiltration, efficacy, antigen recognition, and production of CAR-T in solid tumors. Additional applications of CAR-γδ T and macrophages are also discussed. We believe CAR-T will be a milestone in treating solid tumors once these problems are solved.

The dilemmas and possible solutions for CAR-T cell therapy application in solid tumors

Chimeric antigen receptor T (CAR-T) cell therapy, as an adoptive immunotherapy, is playing an increasingly important role in the treatment of malignant tumors. CAR-T cells are referred to as "living drugs" as they not only target tumor cells directly, but also induce long-term immune memory that has the potential to provide long-lasting protection. CD19.CAR-T cells have achieved complete response rates of over 90 % for acute lymphoblastic leukemia and over 60 % for non-Hodgkin's lymphoma. However, the response rate of CAR-T cells in the treatment of solid tumors remains extremely low and the side effects potentially severe. In this review, we discuss the limitations that the solid tumor microenvironment poses for CAR-T application and the solutions that are being developed to address these limitations, in the hope that in the near future, CAR-T cell therapy for solid tumors can attain the same success rates as are now being seen clinically for hematological malignancies.

In vivo manufacture and manipulation of CAR-T cells for better druggability

The current CAR-T cell therapy products have been hampered in their druggability due to the personalized preparation required, unclear pharmacokinetic characteristics, and unpredictable adverse reactions. Enabling standardized manufacturing and having clear efficacy and pharmacokinetic characteristics are prerequisites for ensuring the effective practicality of CAR-T cell therapy drugs. This review provides a broad overview of the different approaches for controlling behaviors of CAR-T cells in vivo. The utilization of genetically modified vectors enables in vivo production of CAR-T cells, thereby abbreviating or skipping the lengthy in vitro expansion process. By equipping CAR-T cells with intricately designed control elements, using molecule switches or small-molecule inhibitors, the control of CAR-T cell activity can be achieved. Moreover, the on-off control of CAR-T cell activity would yield potential gains in phenotypic remodeling. These methods provide beneficial references for the future development of safe, controllable, convenient, and suitable for standardized production of CAR-T cell therapy products.

Selection, engineering, and in vivo testing of a human leukocyte antigen-independent T-cell receptor recognizing human mesothelin

BACKGROUND

Canonical α/β T-cell receptors (TCRs) bind to human leukocyte antigen (HLA) displaying antigenic peptides to elicit T cell-mediated cytotoxicity. TCR-engineered T-cell immunotherapies targeting cancer-specific peptide-HLA complexes (pHLA) are generating exciting clinical responses, but owing to HLA restriction they are only able to target a subset of antigen-positive patients. More recently, evidence has been published indicating that naturally occurring α/β TCRs can target cell surface proteins other than pHLA, which would address the challenges of HLA restriction. In this proof-of-concept study, we sought to identify and engineer so-called HLA-independent TCRs (HiTs) against the tumor-associated antigen mesothelin.

METHODS

Using phage display, we identified a HiT that bound well to mesothelin, which when expressed in primary T cells, caused activation and cytotoxicity. We subsequently engineered this HiT to modulate the T-cell response to varying levels of mesothelin on the cell surface.

RESULTS

The isolated HiT shows cytotoxic activity and demonstrates killing of both mesothelin-expressing cell lines and patient-derived xenograft models. Additionally, we demonstrated that HiT-transduced T cells do not require CD4 or CD8 co-receptors and, unlike a TCR fusion construct, are not inhibited by soluble mesothelin. Finally, we showed that HiT-transduced T cells are highly efficacious in vivo, completely eradicating xenografted human solid tumors.

CONCLUSION

HiTs can be isolated from fully human TCR-displaying phage libraries against cell surface-expressed antigens. HiTs are able to fully activate primary T cells both in vivo and in vitro. HiTs may enable the efficacy seen with pHLA-targeting TCRs in solid tumors to be translated to cell surface antigens.

Recent advances in CAR T-cell engineering using synthetic biology: Paving the way for next-generation cancer treatment

This book chapter highlights a comprehensive exploration of the transformative innovations in the field of cancer immunotherapy. CAR (Chimeric Antigen Receptor) T-cell therapy represents a groundbreaking approach to treat cancer by reprogramming a patient immune cells to recognize and destroy cancer cells. This chapter underscores the critical role of synthetic biology in enhancing the safety and effectiveness of CAR T-cell therapies. It begins by emphasizing the growing importance of personalized medicine in cancer treatment, emphasizing the shift from one-size-fits-all approaches to patient-specific solutions. Synthetic biology, a multidisciplinary field, has been instrumental in customizing CAR T-cell therapies, allowing for fine-tuned precision and minimizing unwanted side effects. The chapter highlights recent advances in gene editing, synthetic gene circuits, and molecular engineering, showcasing how these technologies are optimizing CAR T-cell function. In summary, this book chapter sheds light on the remarkable progress made in the development of CAR T-cell therapies using synthetic biology, providing hope for cancer patients and hinting at a future where highly personalized and effective cancer treatments are the norm.

Enhancing the safety of CAR-T cell therapy: Synthetic genetic switch for spatiotemporal control

Chimeric antigen receptor T (CAR-T) cell therapy is a promising and precise targeted therapy for cancer that has demonstrated notable potential in clinical applications. However, severe adverse effects limit the clinical application of this therapy and are mainly caused by uncontrollable activation of CAR-T cells, including excessive immune response activation due to unregulated CAR-T cell action time, as well as toxicity resulting from improper spatial localization. Therefore, to enhance controllability and safety, a control module for CAR-T cells is proposed. Synthetic biology based on genetic engineering techniques is being used to construct artificial cells or organisms for specific purposes. This approach has been explored in recent years as a means of achieving controllability in CAR-T cell therapy. In this review, we summarize the recent advances in synthetic biology methods used to address the major adverse effects of CAR-T cell therapy in both the temporal and spatial dimensions.

Synthetic Gene Circuits for Regulation of Next-Generation Cell-Based Therapeutics

Arming human cells with synthetic gene circuits enables to expand their capacity to execute superior sensing and response actions, offering tremendous potential for innovative cellular therapeutics. This can be achieved by assembling components from an ever-expanding molecular toolkit, incorporating switches based on transcriptional, translational, or post-translational control mechanisms. This review provides examples from the three classes of switches, and discusses their advantages and limitations to regulate the activity of therapeutic cells in vivo. Genetic switches designed to recognize internal disease-associated signals often encode intricate actuation programs that orchestrate a reduction in the sensed signal, establishing a closed-loop architecture. Conversely, switches engineered to detect external molecular or physical cues operate in an open-loop fashion, switching on or off upon signal exposure. The integration of such synthetic gene circuits into the next generation of chimeric antigen receptor T-cells is already enabling precise calibration of immune responses in terms of magnitude and timing, thereby improving the potency and safety of therapeutic cells. Furthermore, pre-clinical engineered cells targeting other chronic diseases are gathering increasing attention, and this review discusses the path forward for achieving clinical success. With synthetic biology at the forefront, cellular therapeutics holds great promise for groundbreaking treatments.

Intraperitoneal administration of carcinoembryonic antigen-directed chimeric antigen receptor T cells is a robust delivery route for effective treatment of peritoneal carcinomatosis from colorectal cancer in pre-clinical study

BACKGROUND AIMS

Peritoneal carcinomatosis (PC) from colorectal cancer (CRC) is a highly challenging disease to treat. Systemic chimeric antigen receptor (CAR) T cells have shown impressive efficacy in hematologic malignancies but have been less effective in solid tumors. We explored whether intraperitoneal (i.p.) administration of CAR T cells could provide an effective and robust route of treatment for PC from CRC.

METHODS

We generated second-generation carcinoembryonic antigen (CEA)-specific CAR T cells. Various animal models of PC with i.p. and extraperitoneal metastasis were treated by i.p. or intravenous (i.v.) administration of CEA CAR T cells.

RESULTS

Intraperitoneally administered CAR T cells exhibited superior anti-tumor activity compared with systemic i.v. cell infusion in an animal model of PC. In addition, i.p. administration conferred a durable effect and protection against tumor recurrence and exerted strong anti-tumor activity in an animal model of PC with metastasis in i.p. or extraperitoneal organs. Moreover, compared with systemic delivery, i.p. transfer of CAR T cells provided increased anti-tumor activity in extraperitoneal tumors without PC. This phenomenon was further confirmed in an animal model of pancreatic carcinoma after i.p. administration of our newly constructed prostate stem cell antigen-directed CAR T cells.

CONCLUSIONS

Taken together, our data suggest that i.p. administration of CAR T cells may be a robust delivery route for effective treatment of cancer.

A chimeric antigen receptor-based cellular safeguard mechanism for selective in vivo depletion of engineered T cells

Adoptive immunotherapy based on chimeric antigen receptor (CAR)-engineered T cells has exhibited impressive clinical efficacy in treating B-cell malignancies. However, the potency of CAR-T cells carriethe potential for significant on-target/off-tumor toxicities when target antigens are shared with healthy cells, necessitating the development of complementary safety measures. In this context, there is a need to selectively eliminate therapeutically administered CAR-T cells, especially to revert long-term CAR-T cell-related side effects. To address this, we have developed an effective cellular-based safety mechanism to specifically target and eliminate the transferred CAR-T cells. As proof-of-principle, we have designed a secondary CAR (anti-CAR CAR) capable of recognizing a short peptide sequence (Strep-tag II) incorporated into the hinge domain of an anti-CD19 CAR. In in vitro experiments, these anti-CAR CAR-T cells have demonstrated antigen-specific cytokine release and cytotoxicity when co-cultured with anti-CD19 CAR-T cells. Moreover, in both immunocompromised and immunocompetent mice, we observed the successful depletion of anti-CD19 CAR-T cells when administered concurrently with anti-CAR CAR-T cells. We have also demonstrated the efficacy of this safeguard mechanism in a clinically relevant animal model of B-cell aplasia induced by CD19 CAR treatment, where this side effect was reversed upon anti-CAR CAR-T cells infusion. Notably, efficient B-cell recovery occurred even in the absence of any pre-conditioning regimens prior anti-CAR CAR-T cells transfer, thus enhancing its practical applicability. In summary, we developed a robust cellular safeguard system for selective in vivo elimination of engineered T cells, offering a promising solution to address CAR-T cell-related on-target/off-tumor toxicities.

Hypoxia-Responsive CAR-T Cells Exhibit Reduced Exhaustion and Enhanced Efficacy in Solid Tumors

Expanding the utility of chimeric antigen receptor (CAR)-T cells in solid tumors requires improving their efficacy and safety. Hypoxia is a feature of most solid tumors that could be used to help CAR-T cells discriminate tumors from normal tissues. In this study, we developed hypoxia-responsive CAR-T cells by engineering the CAR to be under regulation of hypoxia-responsive elements and selected the optimal structure (5H1P-CEA CAR), which can be activated in the tumor hypoxic microenvironment to induce CAR-T cells with high polyfunctionality. Hypoxia-responsive CAR T cells were in a "resting" state with low CAR expression under normoxic conditions. Compared with conventional CAR-T cells, hypoxia-responsive CAR-T cells maintained lower differentiation and displayed enhanced oxidative metabolism and proliferation during cultivation, and they sowed a capacity to alleviate the negative effects of hypoxia on T-cell proliferation and metabolism. Furthermore, 5H1P-CEA CAR-T cells exhibited decreased T-cell exhaustion and improved T-cell phenotype in vivo. In patient-derived xenograft models, hypoxia-responsive CAR-T cells induced more durable antitumor activity than their conventional counterparts. Overall, this study provides an approach to limit CAR expression to the hypoxic tumor microenvironment that could help to enhance CAR T-cell efficacy and safety in solid tumors.

SIGNIFICANCE

Engineering CAR-T cells to upregulate CAR expression under hypoxic conditions induces metabolic reprogramming, reduces differentiation, and increases proliferation to enhance their antitumor activity, providing a strategy to improve efficacy and safety.

Core-Shell Microspheres Prepared Using Coaxial Electrostatic Spray for Local Chemotherapy of Solid Tumors

Local chemotherapy is an alternative therapeutic strategy that involves direct delivery of drugs to the tumor site. This approach avoids adverse reactions caused by the systemic distribution of drugs and enhances the tumor-suppressing effect by concentrating the drugs at the tumor site. Drug-loaded microspheres are injectable sustained-release drug carriers that are highly suitable for local chemotherapy. However, a complex preparation process is one of the main technical difficulties limiting the development of microsphere formulations. In this study, core-shell structured microspheres loaded with paclitaxel (PTX; with a core-shell structure, calcium alginate outer layer, and a poly (lactic acid-co-glycolic acid) copolymer inner layer, denoted as PTX-CA/PLGA-MS) were prepared using coaxial electrostatic spray technology and evaluated in vitro and in vivo. PTX-CA/PLGA-MS exhibited a two-stage drug release profile and enhanced anti-tumor effect in animal tumor models. Importantly, the preparation method reported in this study is simple and reduces the amount of organic solvent(s) used substantially.

Evolving CAR-T-Cell Therapy for Cancer Treatment: From Scientific Discovery to Cures

In recent years, chimeric antigen receptor (CAR)-T-cell therapy has emerged as the most promising immunotherapy for cancer that typically uses patients' T cells and genetically engineered them to target cancer cells. Although recent improvements in CAR-T-cell therapy have shown remarkable success for treating hematological malignancies, the heterogeneity in tumor antigens and the immunosuppressive nature of the tumor microenvironment (TME) limits its efficacy in solid tumors. Despite the enormous efforts that have been made to make CAR-T-cell therapy more effective and have minimal side effects for treating hematological malignancies, more research needs to be conducted regarding its use in the clinic for treating various other types of cancer. The main concern for CAR-T-cell therapy is severe toxicities due to the cytokine release syndrome, whereas the other challenges are associated with complexity and immune-suppressing TME, tumor antigen heterogeneity, the difficulty of cell trafficking, CAR-T-cell exhaustion, and reduced cytotoxicity in the tumor site. This review discussed the latest discoveries in CAR-T-cell therapy strategies and combination therapies, as well as their effectiveness in different cancers. It also encompasses ongoing clinical trials; current challenges regarding the therapeutic use of CAR-T-cell therapy, especially for solid tumors; and evolving treatment strategies to improve the therapeutic application of CAR-T-cell therapy.

Building safety into CAR-T therapy

Chimeric antigen receptor T cell (CAR-T) therapy is an innovative immunotherapeutic approach that utilizes genetically modified T-cells to eliminate cancer cells using the specificity of a monoclonal antibody (mAb) coupled to the potent cytotoxicity of the T-lymphocyte. CAR-T therapy has yielded significant improvements in relapsed/refractory B-cell malignancies. Given these successes, CAR-T has quickly spread to other hematologic malignancies and is being increasingly explored in solid tumors. From early clinical applications to present day, CAR-T cell therapy has been accompanied by significant toxicities, namely cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and on-target off-tumor (OTOT) effects. While medical management has improved for CRS and ICANS, the ongoing threat of refractory symptoms and unanticipated idiosyncratic toxicities highlights the need for more powerful safety measures. This is particularly poignant as CAR T-cell therapy continues to expand into the solid tumor space, where the risk of unpredictable toxicities remains high. We will review CAR-T as an immunotherapeutic approach including emergence of unique toxicities throughout development. We will discuss known and novel strategies to mitigate these toxicities; additional safety challenges in the treatment of solid tumors, and how the inducible Caspase 9 "safety switch" provides an ideal platform for continued exploration.

Targeting colorectal cancer cells using AND-gated adaptor RevCAR T-cells

Despite the success of chimeric antigen receptor (CAR) T-cells especially for treating hematological malignancies, critical drawbacks, such as "on-target, off-tumor" toxicities, need to be addressed to improve safety in translating to clinical application. This is especially true, when targeting tumor-associated antigens (TAAs) that are not exclusively expressed by solid tumors but also on hea9lthy tissues. To improve the safety profile, we developed switchable adaptor CAR systems including the RevCAR system. RevCAR T-cells are activated by cross-linking of bifunctional adaptor molecules termed target modules (RevTM). In a further development, we established a Dual-RevCAR system for an AND-gated combinatorial targeting by splitting the stimulatory and co-stimulatory signals of the RevCAR T-cells on two individual CARs. Examples of common markers for colorectal cancer (CRC) are the carcinoembryonic antigen (CEA) and the epithelial cell adhesion molecule (EpCAM), while these antigens are also expressed by healthy cells. Here we describe four novel structurally different RevTMs for targeting of CEA and EpCAM. All anti-CEA and anti-EpCAM RevTMs were validated and the simultaneous targeting of CEA+ and EpCAM+ cancer cells redirected specific in vitro and in vivo killing by Dual-RevCAR T-cells. In summary, we describe the development of CEA and EpCAM specific adaptor RevTMs for monospecific and AND-gated targeting of CRC cells via the RevCAR platform as an improved approach to increase tumor specificity and safety of CAR T-cell therapies.

Immune approaches beyond traditional immune checkpoint inhibitors for advanced renal cell carcinoma

Renal cell carcinoma (RCC), especially clear cell RCC, is generally considered an immunotherapy-responsive cancer. Recently, the prognosis for patients with locally advanced and metastatic RCC has significantly improved with the regulatory approvals of anti-PD-1/PD-L1/CTLA-4 immune checkpoint inhibitor (ICI)-based regimens. Yet in most cases, RCC will remain initially unresponsive to treatment or will develop resistance over time. Hence, there remains an unmet need to understand what leads to ICI resistance and to develop novel immune and nonimmune treatments to enhance the response to ICIs. In this review, we highlight recently published studies and the latest clinical studies investigating the next generation of immune approaches to locally advanced and metastatic RCC beyond traditional ICIs. These trials include cytokines, gut microbiota-based therapies, novel immune checkpoint agents, vaccines, and chimeric antigen receptor T cells. These agents are being evaluated as monotherapy or in combination with traditional ICIs and will hopefully provide improved outcomes to patients with RCC soon.

EpCAM-targeting CAR-T cell immunotherapy is safe and efficacious for epithelial tumors

The efficacy of CAR-T cells for solid tumors is unsatisfactory. EpCAM is a biomarker of epithelial tumors, but the clinical feasibility of CAR-T therapy targeting EpCAM is lacking. Here, we report pre- and clinical investigations of EpCAM-CAR-T cells for solid tumors. We demonstrated that EpCAM-CAR-T cells costimulated by Dectin-1 exhibited robust antitumor activity without adverse effects in xenograft mouse models and EpCAM-humanized mice. Notably, in clinical trials for epithelial tumors (NCT02915445), 6 (50%) of the 12 enrolled patients experienced self-remitted grade 1/2 toxicities, 1 patient (8.3%) experienced reversible grade 3 leukopenia, and no higher-grade toxicity reported. Efficacy analysis determined two patients as partial response. Three patients showed >23 months of progression-free survival, among whom one patient experienced 2-year progress-free survival with detectable CAR-T cells 200 days after infusion. These data demonstrate the feasibility and tolerability of EpCAM-CAR-T therapy.

Dual-inhibitory domain iCARs improve the efficiency of the AND-NOT gate CAR T strategy

CAR (chimeric antigen receptor) T cell therapy has shown clinical success in treating hematological malignancies, but its treatment of solid tumors has been limited. One major challenge is on-target, off-tumor toxicity, where CAR T cells also damage normal tissues that express the targeted antigen. To reduce this detrimental side-effect, Boolean-logic gates like AND-NOT gates have utilized an inhibitory CAR (iCAR) to specifically curb CAR T cell activity at selected nonmalignant tissue sites. However, the strategy seems inefficient, requiring high levels of iCAR and its target antigen for inhibition. Using a TROP2-targeting iCAR with a single PD1 inhibitory domain to inhibit a CEACAM5-targeting CAR (CEACAR), we observed that the inefficiency was due to a kinetic delay in iCAR inhibition of cytotoxicity. To improve iCAR efficiency, we modified three features of the iCAR-the avidity, the affinity, and the intracellular signaling domains. Increasing the avidity but not the affinity of the iCAR led to significant reductions in the delay. iCARs containing twelve different inhibitory signaling domains were screened for improved inhibition, and three domains (BTLA, LAIR-1, and SIGLEC-9) each suppressed CAR T function but did not enhance inhibitory kinetics. When inhibitory domains of LAIR-1 or SIGLEC-9 were combined with PD-1 into a single dual-inhibitory domain iCAR (DiCARs) and tested with the CEACAR, inhibition efficiency improved as evidenced by a significant reduction in the inhibitory delay. These data indicate that a delicate balance between CAR and iCAR signaling strength and kinetics must be achieved to regulate AND-NOT gate CAR T cell selectivity.

Next-generation chimeric antigen receptors for T- and natural killer-cell therapies against cancer

Adoptive cellular therapy using chimeric antigen receptor (CAR) T cells has led to a paradigm shift in the treatment of various hematologic malignancies. However, the broad application of this approach for myeloid malignancies and solid cancers has been limited by the paucity and heterogeneity of target antigen expression, and lack of bona fide tumor-specific antigens that can be targeted without cross-reactivity against normal tissues. This may lead to unwanted on-target off-tumor toxicities that could undermine the desired antitumor effect. Recent advances in synthetic biology and genetic engineering have enabled reprogramming of immune effector cells to enhance their selectivity toward tumors, thus mitigating on-target off-tumor adverse effects. In this review, we outline the current strategies being explored to improve CAR selectivity toward tumor cells with a focus on natural killer (NK) cells, and the progress made in translating these strategies to the clinic.

Toward the clinical development of synthetic immunity to cancer

Synthetic biology (synbio) tools, such as chimeric antigen receptors (CARs), have been designed to target, activate, and improve immune cell responses to tumors. These therapies have demonstrated an ability to cure patients with blood cancers. However, there are significant challenges to designing, testing, and efficiently translating these complex cell therapies for patients who do not respond or have immune refractory solid tumors. The rapid progress of synbio tools for cell therapy, particularly for cancer immunotherapy, is encouraging but our development process should be tailored to increase translational success. Particularly, next-generation cell therapies should be rooted in basic immunology, tested in more predictive preclinical models, engineered for potency with the right balance of safety, educated by clinical findings, and multi-faceted to combat a range of suppressive mechanisms. Here, we lay out five principles for engineering future cell therapies to increase the probability of clinical impact, and in the context of these principles, we provide an overview of the current state of synbio cell therapy design for cancer. Although these principles are anchored in engineering immune cells for cancer therapy, we posit that they can help guide translational synbio research for broad impact in other disease indications with high unmet need.

Coengineering specificity, safety, and function into T cells for cancer immunotherapy

Adoptive T-cell transfer (ACT) therapies, including of tumor infiltrating lymphocytes (TILs) and T cells gene-modified to express either a T cell receptor (TCR) or a chimeric antigen receptor (CAR), have demonstrated clinical efficacy for a proportion of patients and cancer-types. The field of ACT has been driven forward by the clinical success of CD19-CAR therapy against various advanced B-cell malignancies, including curative responses for some leukemia patients. However, relapse remains problematic, in particular for lymphoma. Moreover, for a variety of reasons, relative limited efficacy has been demonstrated for ACT of non-hematological solid tumors. Indeed, in addition to pre-infusion challenges including lymphocyte collection and manufacturing, ACT failure can be attributed to several biological processes post-transfer including, (i) inefficient tumor trafficking, infiltration, expansion and retention, (ii) chronic antigen exposure coupled with insufficient costimulation resulting in T-cell exhaustion, (iii) a range of barriers in the tumor microenvironment (TME) mediated by both tumor cells and suppressive immune infiltrate, (iv) tumor antigen heterogeneity and loss, or down-regulation of antigen presentation machinery, (v) gain of tumor intrinsic mechanisms of resistance such as to apoptosis, and (vi) various forms of toxicity and other adverse events in patients. Affinity-optimized TCRs can improve T-cell function and innovative CAR designs as well as gene-modification strategies can be used to coengineer specificity, safety, and function into T cells. Coengineering strategies can be designed not only to directly support the transferred T cells, but also to block suppressive barriers in the TME and harness endogenous innate and adaptive immunity. Here, we review a selection of the remarkable T-cell coengineering strategies, including of tools, receptors, and gene-cargo, that have been developed in recent years to augment tumor control by ACT, more and more of which are advancing to the clinic.

Challenges and solutions for therapeutic TCR-based agents

Recent development of methods to discover and engineer therapeutic T-cell receptors (TCRs) or antibody mimics of TCRs, and to understand their immunology and pharmacology, lag two decades behind therapeutic antibodies. Yet we have every expectation that TCR-based agents will be similarly important contributors to the treatment of a variety of medical conditions, especially cancers. TCR engineered cells, soluble TCRs and their derivatives, TCR-mimic antibodies, and TCR-based CAR T cells promise the possibility of highly specific drugs that can expand the scope of immunologic agents to recognize intracellular targets, including mutated proteins and undruggable transcription factors, not accessible by traditional antibodies. Hurdles exist regarding discovery, specificity, pharmacokinetics, and best modality of use that will need to be overcome before the full potential of TCR-based agents is achieved. HLA restriction may limit each agent to patient subpopulations and off-target reactivities remain important barriers to widespread development and use of these new agents. In this review we discuss the unique opportunities for these new classes of drugs, describe their unique antigenic targets, compare them to traditional antibody therapeutics and CAR T cells, and review the various obstacles that must be overcome before full application of these drugs can be realized.

Single-cell transcriptomic atlas-guided development of CAR-T cells for the treatment of acute myeloid leukemia

Chimeric antigen receptor T cells (CAR-T cells) have emerged as a powerful treatment option for individuals with B cell malignancies but have yet to achieve success in treating acute myeloid leukemia (AML) due to a lack of safe targets. Here we leveraged an atlas of publicly available RNA-sequencing data of over 500,000 single cells from 15 individuals with AML and tissue from 9 healthy individuals for prediction of target antigens that are expressed on malignant cells but lacking on healthy cells, including T cells. Aided by this high-resolution, single-cell expression approach, we computationally identify colony-stimulating factor 1 receptor and cluster of differentiation 86 as targets for CAR-T cell therapy in AML. Functional validation of these established CAR-T cells shows robust in vitro and in vivo efficacy in cell line- and human-derived AML models with minimal off-target toxicity toward relevant healthy human tissues. This provides a strong rationale for further clinical development.

Conditional Control of Universal CAR T Cells by Cleavable OFF-Switch Adaptors

As living drugs, engineered T cell therapies are revolutionizing disease treatment with their unique functional capabilities. However, they suffer from limitations of potentially unpredictable behavior, toxicities, and nontraditional pharmacokinetics. Engineering conditional control mechanisms responsive to tractable stimuli such as small molecules or light is thus highly desirable. We and others previously developed "universal" chimeric antigen receptors (CARs) that interact with coadministered antibody adaptors to direct target cell killing and T cell activation. Universal CARs are of high therapeutic interest due to their ability to simultaneously target multiple antigens on the same disease or different diseases by combining with adaptors to different antigens. Here, we further enhance the programmability and potential safety of universal CAR T cells by engineering OFF-switch adaptors that can conditionally control CAR activity, including T cell activation, target cell lysis, and transgene expression, in response to a small molecule or light stimulus. Moreover, in adaptor combination assays, OFF-switch adaptors were capable of orthogonal conditional targeting of multiple antigens simultaneously, following Boolean logic. OFF-switch adaptors represent a robust new approach for the precision targeting of universal CAR T cells with potential for enhanced safety.

CAR-Ts redirected against the Thomsen-Friedenreich antigen CD176 mediate specific elimination of malignant cells from leukemia and solid tumors

Introduction

Chimeric antigen receptor-engineered T cells (CAR-Ts) are investigated in various clinical trials for the treatment of cancer entities beyond hematologic malignancies. A major hurdle is the identification of a target antigen with high expression on the tumor but no expression on healthy cells, since "on-target/off-tumor" cytotoxicity is usually intolerable. Approximately 90% of carcinomas and leukemias are positive for the Thomsen-Friedenreich carbohydrate antigen CD176, which is associated with tumor progression, metastasis and therapy resistance. In contrast, CD176 is not accessible for ligand binding on healthy cells due to prolongation by carbohydrate chains or sialylation. Thus, no "on-target/off-tumor" cytotoxicity and low probability of antigen escape is expected for corresponding CD176-CAR-Ts.

Methods

Using the anti-CD176 monoclonal antibody (mAb) Nemod-TF2, the presence of CD176 was evaluated on multiple healthy or cancerous tissues and cells. To target CD176, we generated two different 2nd generation CD176-CAR constructs differing in spacer length. Their specificity for CD176 was tested in reporter cells as well as primary CD8+ T cells upon co-cultivation with CD176+ tumor cell lines as models for CD176+ blood and solid cancer entities, as well as after unmasking CD176 on healthy cells by vibrio cholerae neuraminidase (VCN) treatment. Following that, both CD176-CARs were thoroughly examined for their ability to initiate target-specific T-cell signaling and activation, cytokine release, as well as cytotoxicity.

Results

Specific expression of CD176 was detected on primary tumor tissues as well as on cell lines from corresponding blood and solid cancer entities. CD176-CARs mediated T-cell signaling (NF-κB activation) and T-cell activation (CD69, CD137 expression) upon recognition of CD176+ cancer cell lines and unmasked CD176, whereby a short spacer enabled superior target recognition. Importantly, they also released effector molecules (e.g. interferon-γ, granzyme B and perforin), mediated cytotoxicity against CD176+ cancer cells, and maintained functionality upon repetitive antigen stimulation. Here, CD176L-CAR-Ts exhibited slightly higher proliferation and mediator-release capacities. Since both CD176-CAR-Ts did not react towards CD176- control cells, their response proved to be target-specific.

Discussion

Genetically engineered CD176-CAR-Ts specifically recognize CD176 which is widely expressed on cancer cells. Since CD176 is masked on most healthy cells, this antigen and the corresponding CAR-Ts represent a promising approach for the treatment of various blood and solid cancers while avoiding "on-target/off-tumor" cytotoxicity.

Novel Immune Therapies for Renal Cell Carcinoma: Looking Beyond the Programmed Cell Death Protein 1 and Cytotoxic T-Lymphocyte-Associated Protein 4 Axes

Immunotherapy has revolutionized treatment for patients with advanced and metastatic renal cell carcinoma. Nevertheless, many patients do not benefit or eventually relapse, highlighting the need for novel immune targets to overcome primary and acquired resistance. This review discusses 2 strategies currently being investigated: disabling inhibitory stimuli that maintain immunosuppression ("brakes") and priming the immune system to target tumoral cells ("gas pedals"). We explore each class of novel immunotherapy, including the rationale behind it, supporting preclinical and clinical evidence, and limitations.

Bringing cell therapy to tumors: considerations for optimal CAR binder design

Chimeric antigen receptor (CAR)-T cells have revolutionized the immunotherapy of B-cell malignancies and are poised to expand the range of their impact across a broad range of oncology and non-oncology indications. Critical to the success of a given CAR is the choice of binding domain, as this is the key driver for specificity and plays an important role (along with the rest of the CAR structure) in determining efficacy, potency and durability of the cell therapy. While antibodies have proven to be effective sources of CAR binding domains, it has become apparent that the desired attributes for a CAR binding domain do differ from those of a recombinant antibody. This review will address key factors that need to be considered in choosing the optimal binding domain for a given CAR and how binder properties influence and are influenced by the rest of the CAR.

Ligand-based adoptive T cell targeting CA125 in ovarian cancer

BACKGROUND

Ovarian cancer (OC) is a highly aggressive gynecological malignancy prevalent worldwide. Most OC cases are typically diagnosed at advanced stages, which has led to a 5-year overall survival rate of less than 35% following conventional treatment. Furthermore, immune checkpoint inhibitor therapy has shown limited efficacy in the treatment of patients with OC, and CAR-T therapy has also demonstrated modest results owing to inadequate T cell infiltration. Therefore, novel strategies must be developed to enhance T cell persistence and trafficking within the OC tumor microenvironment.

METHODS

In this study, we developed a novel adoptive T-cell therapy for ovarian cancer based on a chimeric antigen receptor structure. We used a ligand-receptor binding motif to enhance the therapeutic effect of targeting CA125. Since mesothelin can naturally bind to CA125 with high affinity, we concatenated the core-binding fragment of mesothelin with the 4-1BB and CD3ζ signal fragments to assemble a novel CA125-targeting chimeric receptor (CR). The CAR structure targeting CA125 derived from the 4H11 antibody was also constructed. CR- and CAR-encoding RNA were electroporated into T cells to evaluate their antitumor activity both in vitro and in vivo.

RESULTS

While CR-T or CAR-T cells exhibited moderate activity against two ovarian cancer cell lines, T cells co-expressing CR and CAR exhibited a superior killing effect compared to T cells expressing either CR or CAR alone. Furthermore, upon interaction with ovarian tumors, the ability of CR and CAR T cells to release activation markers and functional cytokines increased significantly. Similarly, CR and CAR co-expressing T cells persistently controlled the growth of transplanted ovarian cancer tumors in NSG mice and significantly prolonged the overall survival of tumor-challenged mice. Transcriptome sequencing revealed that the survival and cytotoxicity of T cells co-expressing CR and CAR were significantly altered compared with those of T cells expressing either CR or CAR.

CONCLUSION

Our findings demonstrate that CA125 targeting CR and CAR can synergistically kill ovarian cancer cells, indicating that CA125 targeting by the two binding motifs simultaneously in tumors may improve the therapeutic outcomes of ovarian cancer treatment.

Revolutionizing cancer treatment: a comprehensive review of CAR-T cell therapy

Chimeric antigen receptor (CAR)-T cell therapy is a promising new treatment for cancer that involves genetically modifying a patient's T-cells to recognize and attack cancer cells. This review provides an overview of the latest discoveries and clinical trials related to CAR-T cell therapy, as well as the concept and applications of the therapy. The review also discusses the limitations and potential side effects of CAR-T cell therapy, including the high cost and the risk of cytokine release syndrome and neurotoxicity. While CAR-T cell therapy has shown promising results in the treatment of hematologic malignancies, ongoing research is needed to improve the efficacy and safety of the therapy and expand its use to solid tumors. With continued research and development, CAR-T cell therapy has the potential to revolutionize cancer treatment and improve outcomes for patients with cancer.

Challenges and new technologies in adoptive cell therapy

Adoptive cell therapies (ACTs) have existed for decades. From the initial infusion of tumor-infiltrating lymphocytes to the subsequent specific enhanced T cell receptor (TCR)-T and chimeric antigen receptor (CAR)-T cell therapies, many novel strategies for cancer treatment have been developed. Owing to its promising outcomes, CAR-T cell therapy has revolutionized the field of ACTs, particularly for hematologic malignancies. Despite these advances, CAR-T cell therapy still has limitations in both autologous and allogeneic settings, including practicality and toxicity issues. To overcome these challenges, researchers have focused on the application of CAR engineering technology to other types of immune cell engineering. Consequently, several new cell therapies based on CAR technology have been developed, including CAR-NK, CAR-macrophage, CAR-γδT, and CAR-NKT. In this review, we describe the development, advantages, and possible challenges of the aforementioned ACTs and discuss current strategies aimed at maximizing the therapeutic potential of ACTs. We also provide an overview of the various gene transduction strategies employed in immunotherapy given their importance in immune cell engineering. Furthermore, we discuss the possibility that strategies capable of creating a positive feedback immune circuit, as healthy immune systems do, could address the flaw of a single type of ACT, and thus serve as key players in future cancer immunotherapy.

B7-H3-targeted CAR T cell activity is enhanced by radiotherapy in solid cancers

Adoptive cell therapy utilizing T cells genetically modified to express a chimeric antigen receptor (CAR) has demonstrated promising clinical results in hematological malignancies. However, solid cancers have not seen a similar success due to multiple obstacles. Investigating these escape mechanisms and designing strategies to counteract such limitations is crucial and timely. Growing evidence in the literature supports the hypothesis that radiotherapy has the potential to enhance the susceptibility of solid tumors to CAR T cell therapy, by overcoming mechanisms of resistance. Radiation treatment can increase the susceptibility of different types of solid cancers (TNBC, HNSCC, PDAC) to B7-H3 CAR T cell-mediated eradication. Multiple mechanisms, including reduced cancer cell proliferation, upregulation of the targeted antigen, modulation of apoptotic molecules may contribute to this signal. The information in the literature and the results we describesupport the ability of radiotherapy to improve the efficacy of CAR T cell therapy in solid tumors.

Harnessing the potential of CAR-T cell therapy: progress, challenges, and future directions in hematological and solid tumor treatments

Traditional cancer treatments use nonspecific drugs and monoclonal antibodies to target tumor cells. Chimeric antigen receptor (CAR)-T cell therapy, however, leverages the immune system's T-cells to recognize and attack tumor cells. T-cells are isolated from patients and modified to target tumor-associated antigens. CAR-T therapy has achieved FDA approval for treating blood cancers like B-cell acute lymphoblastic leukemia, large B-cell lymphoma, and multiple myeloma by targeting CD-19 and B-cell maturation antigens. Bi-specific chimeric antigen receptors may contribute to mitigating tumor antigen escape, but their efficacy could be limited in cases where certain tumor cells do not express the targeted antigens. Despite success in blood cancers, CAR-T technology faces challenges in solid tumors, including lack of reliable tumor-associated antigens, hypoxic cores, immunosuppressive tumor environments, enhanced reactive oxygen species, and decreased T-cell infiltration. To overcome these challenges, current research aims to identify reliable tumor-associated antigens and develop cost-effective, tumor microenvironment-specific CAR-T cells. This review covers the evolution of CAR-T therapy against various tumors, including hematological and solid tumors, highlights challenges faced by CAR-T cell therapy, and suggests strategies to overcome these obstacles, such as utilizing single-cell RNA sequencing and artificial intelligence to optimize clinical-grade CAR-T cells.

Theranostic chimeric antigen receptor (CAR)-T cells: Insight into recent trends and challenges in solid tumors

Cell therapy has reached significant milestones in various life-threatening diseases, including cancer. Cell therapy using fluorescent and radiolabeled chimeric antigen receptor (CAR)-T cell is a successful strategy for diagnosing or treating malignancies. Since cell therapy approaches have different results in cancers, the success of hematological cancers has yet to transfer to solid tumor therapy, leading to more casualties. Therefore, there are many areas for improvement in the cell therapy platform. Understanding the therapeutic barriers associated with solid cancers through cell tracking and molecular imaging may provide a platform for effectively delivering CAR-T cells into solid tumors. This review describes CAR-T cells' role in treating solid and non-solid tumors and recent advances. Furthermore, we discuss the main obstacles, mechanism of action, novel strategies and solutions to overcome the challenges from molecular imaging and cell tracking perspectives.

Screening and characterization of the scFv for chimeric antigen receptor T cells targeting CEA-positive carcinoma

Introduction

Chimeric antigen receptor T (CAR-T) cell therapy presents a promising treatment option for various cancers, including solid tumors. Carcinoembryonic antigen (CEA) is an attractive target due to its high expression in many tumors, particularly gastrointestinal cancers, while limited expression in normal adult tissues. In our previous clinical study, we reported a 70% disease control rate with no severe side effects using a humanized CEA-targeting CAR-T cell. However, the selection of the appropriate single-chain variable fragment (scFv) significantly affects the therapeutic efficacy of CAR-T cells by defining their specific behavior towards the target antigen. Therefore, this study aimed to identify the optimal scFv and investigate its biological functions to further optimize the therapeutic potential of CAR-T cells targeting CEA-positive carcinoma.

Methods

We screened four reported humanized or fully human anti-CEA antibodies (M5A, hMN-14, BW431/26, and C2-45), and inserted them into a 3rd-generation CAR structure. We purified the scFvs and measured the affinity. We monitored CAR-T cell phenotype and scFv binding stability to CEA antigen through flow cytometry. We performed repeated CEA antigen stimulation assays to compare the proliferation potential and response of the four CAR-T cells, then further evaluated the anti-tumor efficacy of CAR-T cells ex vivo and in vivo.

Results

M5A and hMN-14 CARs displayed higher affinity and more stable CEA binding ability than BW431/26 and C2-45 CARs. During CAR-T cell production culture, hMN-14 CAR-T cells exhibit a larger proportion of memory-like T cells, while M5A CAR-T cells showed a more differentiated phenotype, suggesting a greater tonic signal of M5A scFv. M5A, hMN-14, and BW431/26 CAR-T cells exhibited effective tumor cell lysis and IFN-γ release when cocultured with CEA-positive tumor cells in vitro, correlating with the abundance of CEA expression in target cells. While C2-45 resulted in almost no tumor lysis or IFN-γ release. In a repeat CEA antigen stimulation assay, M5A showed the best cell proliferation and cytokine secretion levels. In a mouse xenograft model, M5A CAR-T cells displayed better antitumor efficacy without preconditioning.

Discussion

Our findings suggest that scFvs derived from different antibodies have distinctive characteristics, and stable expression and appropriate affinity are critical for robust antitumor efficacy. This study highlights the importance of selecting an optimal scFv in CAR-T cell design for effective CEA-targeted therapy. The identified optimal scFv, M5A, could be potentially applied in future clinical trials of CAR-T cell therapy targeting CEA-positive carcinoma.

Targeting Stage-Specific Embryonic Antigen 4 (SSEA-4) in Triple Negative Breast Cancer by CAR T Cells Results in Unexpected on Target/off Tumor Toxicities in Mice

Due to the paucity of targetable antigens, triple-negative breast cancer (TNBC) remains a challenging subtype of breast cancer to treat. In this study, we developed and evaluated a chimeric antigen receptor (CAR) T cell-based treatment modality for TNBC by targeting stage-specific embryonic antigen 4 (SSEA-4), a glycolipid whose overexpression in TNBC has been correlated with metastasis and chemoresistance. To delineate the optimal CAR configuration, a panel of SSEA-4-specific CARs containing alternative extracellular spacer domains was constructed. The different CAR constructs mediated antigen-specific T cell activation characterized by degranulation of T cells, secretion of inflammatory cytokines, and killing of SSEA-4-expressing target cells, but the extent of this activation differed depending on the length of the spacer region. Adoptive transfer of the CAR-engineered T cells into mice with subcutaneous TNBC xenografts mediated a limited antitumor effect but induced severe toxicity symptoms in the cohort receiving the most bioactive CAR variant. We found that progenitor cells in the lung and bone marrow express SSEA-4 and are likely co-targeted by the CAR T cells. Thus, this study has revealed serious adverse effects that raise safety concerns for SSEA-4-directed CAR therapies because of the risk of eliminating vital cells with stem cell properties.

Conditional control of universal CAR T cells by cleavable OFF-switch adaptors

As living drugs, engineered T cell therapies are revolutionizing disease treatment with their unique functional capabilities. However, they suffer from limitations of potentially unpredictable behavior, toxicities, and non-traditional pharmacokinetics. Engineering conditional control mechanisms responsive to tractable stimuli such as small molecules or light is thus highly desirable. We and others previously developed "universal" chimeric antigen receptors (CARs) that interact with co-administered antibody adaptors to direct target cell killing and T cell activation. Universal CARs are of high therapeutic interest due to their ability to simultaneously target multiple antigens on the same disease or different diseases by combining with adaptors to different antigens. Here, we further enhance the programmability and potential safety of universal CAR T cells by engineering OFF-switch adaptors that can conditionally control CAR activity, including T cell activation, target cell lysis, and transgene expression, in response to a small molecule or light stimulus. Moreover, in adaptor combination assays, OFF-switch adaptors were capable of orthogonal conditional targeting of multiple antigens simultaneously following Boolean logic. OFF-switch adaptors represent a robust new approach for precision targeting of universal CAR T cells with potential for enhanced safety.

Inducible expression of interleukin-12 augments the efficacy of affinity-tuned chimeric antigen receptors in murine solid tumor models

The limited number of targetable tumor-specific antigens and the immunosuppressive nature of the microenvironment within solid malignancies represent major barriers to the success of chimeric antigen receptor (CAR)-T cell therapies. Here, using epithelial cell adhesion molecule (EpCAM) as a model antigen, we used alanine scanning of the complementarity-determining region to fine-tune CAR affinity. This allowed us to identify CARs that could spare primary epithelial cells while still effectively targeting EpCAM^high tumors. Although affinity-tuned CARs showed suboptimal antitumor activity in vivo, we found that inducible secretion of interleukin-12 (IL-12), under the control of the NFAT promoter, can restore CAR activity to levels close to that of the parental CAR. This strategy was further validated with another affinity-tuned CAR specific for intercellular adhesion molecule-1 (ICAM-1). Only in affinity-tuned CAR-T cells was NFAT activity stringently controlled and restricted to tumors expressing the antigen of interest at high levels. Our study demonstrates the feasibility of specifically gearing CAR-T cells towards recognition of solid tumors by combining inducible IL-12 expression and affinity-tuned CAR.

Co-opting signalling molecules enables logic-gated control of CAR T cells

Although chimeric antigen receptor (CAR) T cells have altered the treatment landscape for B cell malignancies, the risk of on-target, off-tumour toxicity has hampered their development for solid tumours because most target antigens are shared with normal cells1,2. Researchers have attempted to apply Boolean-logic gating to CAR T cells to prevent toxicity3-5; however, a truly safe and effective logic-gated CAR has remained elusive6. Here we describe an approach to CAR engineering in which we replace traditional CD3ζ domains with intracellular proximal T cell signalling molecules. We show that certain proximal signalling CARs, such as a ZAP-70 CAR, can activate T cells and eradicate tumours in vivo while bypassing upstream signalling proteins, including CD3ζ. The primary role of ZAP-70 is to phosphorylate LAT and SLP-76, which form a scaffold for signal propagation. We exploited the cooperative role of LAT and SLP-76 to engineer logic-gated intracellular network (LINK) CAR, a rapid and reversible Boolean-logic AND-gated CAR T cell platform that outperforms other systems in both efficacy and prevention of on-target, off-tumour toxicity. LINK CAR will expand the range of molecules that can be targeted with CAR T cells, and will enable these powerful therapeutic agents to be used for solid tumours and diverse diseases such as autoimmunity7 and fibrosis8. In addition, this work shows that the internal signalling machinery of cells can be repurposed into surface receptors, which could open new avenues for cellular engineering.

Oncolytic adenovirus-mediated expression of CCL5 and IL12 facilitates CA9-targeting CAR-T therapy against renal cell carcinoma

Chimeric antigen receptor T-cell (CAR-T) is particularly prominent in hematological but not in solid tumors, mainly based on the complex tumor immune microenvironment. Oncolytic virus (OVs) is an emerging adjuvant therapy method. OVs may prime tumor lesions to induce anti-tumor immune response, thereby enhancing CAR-T cells functionality and possibly increasing response rates. Here, we combined CAR-T cells targeting carbonic anhydrase 9 (CA9) and an oncolytic adenovirus (OAV) carrying chemokine (C-C motif) ligand 5 (CCL5), cytokine interleukin-12 (IL12) to explore the anti-tumor effects of this combination strategy. The data showed that Ad5-ZD55-hCCL5-hIL12 could infect and replicate in renal cancer cell lines and induced a moderate inhibition of xenografted tumor in nude mice. IL12 mediated by Ad5-ZD55-hCCL5-hIL12 promoted the phosphorylation of Stat4 in CAR-T cells, induced CAR-T cells to secrete more IFN-γ. We also found that Ad5-ZD55-hCCL5-hIL-12 combined with CA9-CAR-T cells significantly increased the infiltration of CAR-T cells in tumor mass, prolonged the survival of the mice and restrained tumor growth in immunodeficient mice. Ad5-ZD55-mCCL5-mIL-12 could also increase CD45⁺CD3⁺T cell infiltration and prolong mice survival in immunocompetent mice. These results provided feasibility for the combination of oncolytic adenovirus and CAR-T cells, which demonstrated the sufficient potential and prospects of CAR-T for the treatment of solid tumors.

Chimeric antigen receptor T cells therapy in solid tumors

Chimeric antigen receptor T cells therapy (CAR-T therapy) is a class of ACT therapy. Chimeric antigen receptor (CAR) is an engineered synthetic receptor of CAR-T, which give T cells the ability to recognize tumor antigens in a human leukocyte antigen-independent (HLA-independent) manner and enables them to recognize more extensive target antigens than natural T cell surface receptor (TCR), resulting in tumor destruction. CAR-T is composed of an extracellular single-chain variable fragment (scFv) of antibody, which serves as the targeting moiety, hinge region, transmembrane spacer, and intracellular signaling domain(s). CAR-T has been developing in many generations, which differ according to costimulatory domains. CAR-T therapy has several limitations that reduce its wide availability in immunotherapy which we can summarize in antigen escape that shows either partial or complete loss of target antigen expression, so multiplexing CAR-T cells are promoted to enhance targeting of tumor profiles. In addition, the large diversity in the tumor microenvironment also plays a major role in limiting this kind of treatment. Therefore, engineered CAR-T cells can evoke immunostimulatory signals that rebalance the tumor microenvironment. Using CAR-T therapy in treating the solid tumor is mainly restricted by the difficulty of CAR-T cells infiltrating the tumor site, so local administration was developed to improve the quality of treatment. The most severe toxicity after CAR-T therapy is on-target/on-tumor toxicity, such as cytokine release syndrome (CRS). Another type of toxicity is on-target/off-tumor toxicity which originates from the binding of CAR-T cells to target antigen that has shared expression on normal cells leading to damage in healthy cells and organs. Toxicity management should become a focus of implementation to permit management beyond specialized centers.

CAR Based Immunotherapy of Solid Tumours-A Clinically Based Review of Target Antigens

Immunotherapy with CAR-engineered immune cells has transformed the management of selected haematological cancers. However, solid tumours have proven much more difficult to control using this emerging therapeutic modality. In this review, we survey the clinical impact of solid tumour CAR-based immunotherapy, focusing on specific targets across a range of disease indications Among the many candidates which have been the subject of non-clinical CAR T-cell research, clinical data are available for studies involving 30 of these targets. Here, we map out this clinical experience, highlighting challenges such as immunogenicity and on-target off-tumour toxicity, an issue that has been both unexpected and devastating in some cases. We also summarise how regional delivery and repeated dosing have been used in an effort to enhance impact and safety. Finally, we consider how emerging armouring systems and multi-targeted CAR approaches might be used to enhance tumour access and better enable discrimination between healthy and transformed cell types.

RUNX3 improves CAR-T cell phenotype and reduces cytokine release while maintaining CAR-T function

CAR-T therapy has shown successful in the treatment of certain types of hematological malignancy, while the efficacy of CAR-T cell in treating solid tumors has been limited due to the exhaustion of CAR-T caused by the tumor microenvironment in solid tumors. Therefore, improving the exhaustion of CAR-T cell is one of the inspiring strategies for CAR-T treatment of solid tumors. As an important regulator in T cell immunity, the transcription factor RUNX3 not only negatively regulates the terminal differentiation T-bet gene, reducing the ultimate differentiation of T cells, but also increases the residency of T cells in non-lymphoid tissues and tumors. By overexpressing RUNX3 in CAR-T cells, we found that increasing the expression of RUNX3 maintained the low differentiation of CAR-T cells, further improving the exhaustion of CAR-T cells during antigen stimulation. In vitro, we found that RUNX3 could reduce the release of cytokines while maintaining CAR-T cells function. In re-challenge experiments, CAR-T cells overexpressing RUNX3 (Runx3-OE CAR-T) were safer than conventional CAR-T cells, while RUNX3 could also maintain the anti-tumor efficacy of CAR-T cells in vivo. Collectively, we found that Runx3-OE CAR-T cells can improve CAR-T phenotype and reduce cytokines release while maintaining CAR-T cells function, which may improve the safety of CAR-T therapy in clinical trials.

Chimeric Antigen Receptor T-Cell Therapy for Solid Tumors: The Past and the Future

Chimeric antigen receptor (CAR) T-cell therapy is the new standard treatment for various indications in patients with advanced hematologic malignancies. Despite the several preclinical and early phase clinical trials, the overall clinical experience has been disappointing when applying this innovative therapy in solid tumors. The failure of CAR T-cell therapy and its limited antitumor activity in solid tumors have been attributed to several mechanisms, including tumor antigen heterogeneity, the hostile tumor microenvironment and poor trafficking of CAR T cells into tumor sites, and the unacceptable toxicities in some settings, among others. However, remarkable improvements have been made in understanding many of these failure mechanisms for which several emerging novel approaches are being applied to overcome these challenges. In this review, after a brief historic background for immunotherapy in solid tumors, we highlight the recent developments achieved in CAR T-cell designs, summarize completed clinical trials, and discuss current challenges facing CAR T-cell therapy and the suggested strategies to overcome these barriers.

CAR immune cells: design principles, resistance and the next generation

The remarkable clinical activity of chimeric antigen receptor (CAR) therapies in B cell and plasma cell malignancies has validated the use of this therapeutic class for liquid cancers, but resistance and limited access remain as barriers to broader application. Here we review the immunobiology and design principles of current prototype CARs and present emerging platforms that are anticipated to drive future clinical advances. The field is witnessing a rapid expansion of next-generation CAR immune cell technologies designed to enhance efficacy, safety and access. Substantial progress has been made in augmenting immune cell fitness, activating endogenous immunity, arming cells to resist suppression via the tumour microenvironment and developing approaches to modulate antigen density thresholds. Increasingly sophisticated multispecific, logic-gated and regulatable CARs display the potential to overcome resistance and increase safety. Early signs of progress with stealth, virus-free and in vivo gene delivery platforms provide potential paths for reduced costs and increased access of cell therapies in the future. The continuing clinical success of CAR T cells in liquid cancers is driving the development of increasingly sophisticated immune cell therapies that are poised to translate to treatments for solid cancers and non-malignant diseases in the coming years.

Generation of antigen-specific T lymphocytes targeting Wilms tumor 1 using activated B cells

In order to develop a therapeutic target for T cells, it is necessary to amplify T cells and increase activity through antigen-presenting cells (APCs) expressing an intracellular cancer antigen. Although dendritic cells are frequently used as APCs, producing dendritic cells is costly and time-consuming. In addition, as dendritic cells are attached cells, they are not suitable for mass production for use as immune cell therapy. On the other hand, B cells are non-adherent floating cells, and thus can easily be cultured in suspension systems. As such, B cells can be considered as suitable substance cells for the development of immune cell therapeutics.B cells lack the antigen-presenting ability of dendritic cells. Therefore, to use B cells as APCs, we previously reported a technology that can be used which simply and effectively produces anti-viral T cells in vitro by activating B cells with α-galactosylceramide (α-GalCer). To apply this technology to anti-cancer treatment, Wilms tumor 1, the most representative cancer antigen expressed in various cancers, was selected. Wilms tumor 1 (WT1) was used to produce anti-cancer (anti-WT1) T cells using active B cells as APCs, and their respective activities were investigated.

[Recent Progress of Nano-drug Combined with Chimeric Antigen Receptor T Cell Therapy in the Treatment of Soild Tumors]

Chimeric antigen receptor T cell (CAR-T) therapy has shown remarkable success in treating hematological malignancies. However, CAR-T therapy for solid tumors is still limited due to the unique solid-tumor microenvironment and heterogeneous target antigen expression, which leads to an urgent need of combining other therapies. At present, nano delivery system has become one of the most promising directions for the development of anti-tumor drugs. Based on the background of CAR-T and tumor treatment, we focus on the research progress of nanomedicine combined with CAR-T therapy, and systematically review the strategies and examples in recent years in the aspects of in vivo delivery of mRNA, regulation of tumor microenvironment, combination with photothermal therapy. And we also look forward to the future direction of this filed.
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Definition and Characterization of SOX11-Derived T Cell Epitopes towards Immunotherapy of Glioma

The transcription factor SOX11 is a tumor-associated antigen with low expression in normal cells, but overexpression in glioblastoma (GBM). So far, conventional surgery, chemotherapy, and radiotherapy have not substantially improved the dismal prognosis of relapsed/refractory GBM patients. Immunotherapy is considered a promising strategy against GBM, but there is a fervent need for better immunotargets in GBM. To this end, we performed an in silico prediction study on SOX11, which primarily yielded ten promising HLA-A*0201-restricted peptides derived from SOX11. We defined a novel peptide FMACSPVAL, which had the highest score according to in silico prediction (6.02 nM by NetMHC-4.0) and showed an exquisite binding affinity to the HLA-A*0201 molecule in the peptide-binding assays. In the IFN-γ ELISPOT assays, FMACSPVAL demonstrated a high efficiency for generating SOX11-specific CD8⁺ T cells. Nine out of thirty-two healthy donors showed a positive response to SOX11, as assessed by the ELISPOT assays. Therefore, this novel antigen peptide epitope seems to be promising as a target for T cell-based immunotherapy in GBM. The adoptive transfer of in vitro elicited SOX11-specific CD8⁺ T cells constitutes a potential approach for the treatment of GBM patients.