Interleukin-6-knockdown of chimeric antigen receptor-modified T cells significantly reduces IL-6 release from monocytes

Safe and potent anti-CD19 CAR T-cells with shRNA-IL-6 gene silencing element in patients with refractory or relapsed B-cell acute lymphoblastic leukemia

Severe cytokine release syndrome (sCRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) have limited the widespread use of chimeric antigen receptor T (CAR T)-cell therapy. We designed a novel anti-CD19 CAR (ssCART-19) with a small hairpin RNA (shRNA) element to silence the interleukin-6 (IL-6) gene, hypothesizing it could reduce sCRS and ICANS by alleviating monocyte activation and proinflammatory cytokine release. In a post hoc analysis of two clinical trials, we compared ssCART-19 with common CAR T-cells (cCART-19) in relapsed/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL). Among 87 patients, 47 received ssCART-19 and 40 received cCART-19. Grade ≥3 CRS occurred in 14.89% (7/47) of the ssCART-19 group versus 37.5% (15/40) in the cCART-19 group (p = 0.036). ICANS occurred in 4.26% (2/47) of the ssCART-19 group (all grade 1) compared to 15% (2/40) of the cCART-19 group. Patients in the ssCART-19 group showed comparable rates of treatment response (calculated with rates of complete remission and incomplete hematological recovery) were 91.49% (43/47) for ssCART-19 and 85% (34/40) for cCART-19 (p = 0.999). With a median follow-up of 21.9 months, cumulative nonrelapse mortality was 10.4% for ssCART-19 and 13.6% for cCART-19 (p = 0.33). Median overall survival was 37.17 months for ssCART-19 and 32.93 months for cCART-19 (p = 0.40). Median progression-free survival was 24.17 months for ssCART-19 and 9.33 months for cCART-19 (p = 0.23). These data support the safety and efficacy of ssCART-19 for r/r B-ALL, suggesting its potential as a promising therapy.

ReCARving the future: bridging CAR T-cell therapy gaps with synthetic biology, engineering, and economic insights

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of hematologic malignancies, offering remarkable remission rates in otherwise refractory conditions. However, its expansion into broader oncological applications faces significant hurdles, including limited efficacy in solid tumors, safety concerns related to toxicity, and logistical challenges in manufacturing and scalability. This review critically examines the latest advancements aimed at overcoming these obstacles, highlighting innovations in CAR T-cell engineering, novel antigen targeting strategies, and improvements in delivery and persistence within the tumor microenvironment. We also discuss the development of allogeneic CAR T cells as off-the-shelf therapies, strategies to mitigate adverse effects, and the integration of CAR T cells with other therapeutic modalities. This comprehensive analysis underscores the synergistic potential of these strategies to enhance the safety, efficacy, and accessibility of CAR T-cell therapies, providing a forward-looking perspective on their evolutionary trajectory in cancer treatment.

Humanization of the antigen-recognition domain does not impinge on the antigen-binding, cytokine secretion, and antitumor reactivity of humanized nanobody-based CD19-redirected CAR-T cells

BACKGROUND

The immunogenicity of the antigen-recognition domains of chimeric antigen receptor (CAR)-T cells leads to immune responses that may compromise the antitumor effects of the adoptively transferred T cells. Herein, we attempt to humanize a CD19-specific VHH (named H85) using in silico techniques and investigate the impact of antigen-recognition domain humanization on CAR expression and density, cytokine secretion, and cytolytic reactivity of CAR-T cells based on the humanized VHH.

METHODS

H85 was humanized (named HuH85), and then HuH85 was compared with H85 in terms of conformational structure, physicochemical properties, antigenicity and immunogenicity, solubility, flexibility, stability, and CD19-binding capacity using in silico techniques. Next, H85CAR-T cells and HuH85CAR-T cells were developed and CAR expression and surface density were assessed via flow cytometry. Ultimately, the antitumor reactivity and secreted levels of IFN-γ, IL-2, and TNF-α were assessed following the co-cultivation of the CAR-T cells with Ramos, Namalwa, and K562 cells.

RESULTS

In silico findings demonstrated no negative impacts on HuH85 as a result of humanization. Ultimately, H85CAR and HuH85CAR could be surface-expressed on transduced T cells at comparable levels as assessed via mean fluorescence intensity. Moreover, H85CAR-T cells and HuH85CAR-T cells mediated comparable antitumor effects against Ramos and Namalwa cells and secreted comparable levels of IFN-γ, IL-2, and TNF-α following co-cultivation.

CONCLUSION

HuH85 can be used to develop immunotherapeutics against CD19-associated hematologic malignancies. Moreover, HuH85CAR-T cells must be further investigated in vitro and in preclinical xenograft models of CD19+ leukemias and lymphomas before advancing into clinical trials.

A novel safer CD19CAR with shRNA interference of IFN-γ can reduce multiple cytokine levels without significantly compromising its killing efficacy

Cytokine release syndrome (CRS) is a great challenge for the application of anti-CD19 CAR-T cell therapy. The aim of this study was to investigate the effect of knocking down interferon gamma (IFN-γ) by shRNA as a potential strategy to reduce the cytokine storms. A newly designed short hairpin interference RNA of IFN-γ (shIFN-γ) in CD19CAR gene was constructed. Several cellular model systems of approach using Nalm-6 cell lines including Nalm-6CD19pos and Nalm-6CD19neg with or without monocytes and endothelial cells were used to analyze the different levels of cytokines after shIFN-γ-anti-CD19CAR-T cell targeted therapy. The activity of this novel CD19CAR-T was evaluated both in vitro and in NSG mouse model. The killing efficacy of shIFN-γ-anti-CD19CAR-T at the E:T ratio of 2:1 was similar to that of regular anti-CD19CAR-T at the E:T ratio of 1:1. The IFN-γ level in the shIFN-γ-anti-CD19CAR-T cell group was (2673.1 ± 307.4) pg/ml at the E:T ratio of 2:1 which was significantly lower than that ((8261.5 ± 345.5) pg/ml) in the regular anti-CD19CAR-T group at the E:T ratio of 1:1. Cytotoxicity experiments in vitro showed significantly reduced concentrations of IFN-γ, IL-6 and TNFα in the shIFN-γ-anti-CD19CAR-T cell group compared to regular anti-CD19CAR-T cell group. Both regular anti-CD19CAR and shIFN-γ-CD19CAR-T exerted bystander killing effect in vitro. We conclude that shIFN-γ-anti-CD19CAR-T cells can reduce the generation of cytokine storms without significantly compromising their therapeutic efficacy in the preclinical setting. In mouse model, 3 × 106 shIFN-γ-anti-CD19CAR-T cells/mouse generated the similar killing efficacy to that with 2 × 106 regular anti-CD19CAR-T cells/mouse.

Inhibition of PKM2 suppresses osteoclastogenesis and alleviates bone loss in mouse periodontitis

BACKGROUND

Chronic periodontitis triggers an increase in osteoclastogenesis, with glycolysis playing a crucial role in this process. Pyruvate kinase M2 (PKM2) is a critical enzyme involved in glycolysis and pyruvate metabolism. Yet, the precise function of PKM2 in osteoclasts and their formation remains unclear and requires further investigation.

METHODS

Bioinformatics was used to investigate critical biological processes in osteoclastogenesis. In vitro, osteoclastogenesis was analyzed using tartrate-resistant acid phosphatase (TRAP) staining, phalloidin staining, quantitative real‑time PCR (RT-qPCR), and Western blotting. Small interfering RNA (siRNA) of PKM2 and Shikonin, a specific inhibitor of PKM2, were used to verify the role of PKM2 in osteoclastogenesis. The mouse model of periodontitis was used to assess the effect of shikonin on bone loss. Analyses included micro computed tomography, immunohistochemistry, flow cytometry, TRAP staining and HE staining.

RESULTS

Bioinformatic analysis revealed a significant impact of glycolysis and pyruvate metabolism on osteoclastogenesis. Inhibition of PKM2 leads to a significant reduction in osteoclastogenesis. In vitro, co-culture of the heat-killed Porphyromonas gingivalis significantly promoted osteoclastogenesis, concomitant with an increased PKM2 expression in osteoclasts. Shikonin weakened the promoting effect of porphyromonas gingivalis on osteoclastogenesis. In vivo experiments demonstrated that inhibition of PKM2 by shikonin alleviated bone loss induced by periodontitis, suppressed excessive osteoclastogenesis in alveolar bone, and reduced tissue inflammation to some extent.

CONCLUSION

PKM2 inhibition by shikonin, a specific inhibitor of this enzyme, attenuated osteoclastogenesis and bone resorption in periodontitis. Shikonin appears to be a promising therapeutic agent for treating periodontitis.

CAR-T cell therapeutic avenue for fighting cardiac fibrosis: Roadblocks and perspectives

Heart diseases remain the primary cause of human mortality in the world. Although conventional therapeutic opportunities fail to halt or recover cardiac fibrosis, the promising clinical results and therapeutic efficacy of engineered chimeric antigen receptor (CAR) T cell therapy show several advancements. However, the current models of CAR-T cells need further improvement since the T cells are associated with the triggering of excessive inflammatory cytokines that directly affect cardiac functions. Thus, the current study highlights the critical function of heart immune cells in tissue fibrosis and repair. The study also confirms CAR-T cell as an emerging therapeutic for treating cardiac fibrosis, explores the current roadblocks to CAR-T cell therapy, and considers future outlooks for research development.

Genome Engineering as a Therapeutic Approach in Cancer Therapy: A Comprehensive Review

Cancer is one of the foremost causes of mortality. The human genome remains stable over time. However, human activities and environmental factors have the power to influence the prevalence of certain types of mutations. This goes to the excessive progress of xenobiotics and industrial development that is expanding the territory for cancers to develop. The mechanisms involved in immune responses against cancer are widely studied. Genome editing has changed the genome-based immunotherapy process in the human body and has opened a new era for cancer treatment. In this review, recent cancer immunotherapies and the use of genome engineering technology are largely focused on.

Revolutionizing cancer treatment: enhancing CAR-T cell therapy with CRISPR/Cas9 gene editing technology

CAR-T cell therapy, a novel immunotherapy, has made significant breakthroughs in clinical practice, particularly in treating B-cell-associated leukemia and lymphoma. However, it still faces challenges such as poor persistence, limited proliferation capacity, high manufacturing costs, and suboptimal efficacy. CRISPR/Cas system, an efficient and simple method for precise gene editing, offers new possibilities for optimizing CAR-T cells. It can increase the function of CAR-T cells and reduce manufacturing costs. The combination of CRISPR/Cas9 technology and CAR-T cell therapy may promote the development of this therapy and provide more effective and personalized treatment for cancer patients. Meanwhile, the safety issues surrounding the application of this technology in CAR-T cells require further research and evaluation. Future research should focus on improving the accuracy and safety of CRISPR/Cas9 technology to facilitate the better development and application of CAR-T cell therapy. This review focuses on the application of CRISPR/Cas9 technology in CAR-T cell therapy, including eliminating the inhibitory effect of immune checkpoints, enhancing the ability of CAR-T cells to resist exhaustion, assisting in the construction of universal CAR-T cells, reducing the manufacturing costs of CAR-T cells, and the security problems faced. The objective is to show the revolutionary role of CRISPR/Cas9 technology in CAR-T cell therapy for researchers.

Cytokine Modification of Adoptive Chimeric Antigen Receptor Immunotherapy for Glioblastoma

Chimeric antigen receptor (CAR) cell-based therapies have demonstrated limited success in solid tumors, including glioblastoma (GBM). GBMs exhibit high heterogeneity and create an immunosuppressive tumor microenvironment (TME). In addition, other challenges exist for CAR therapy, including trafficking and infiltration into the tumor site, proliferation, persistence of CARs once in the tumor, and reduced functionality, such as suboptimal cytokine production. Cytokine modification is of interest, as one can enhance therapy efficacy and minimize off-target toxicity by directly combining CAR therapy with cytokines, antibodies, or oncolytic viruses that alter cytokine response pathways. Alternatively, one can genetically modify CAR T-cells or CAR NK-cells to secrete cytokines or express cytokines or cytokine receptors. Finally, CARs can be genetically altered to augment or suppress intracellular cytokine signaling pathways for a more direct approach. Codelivery of cytokines with CARs is the most straightforward method, but it has associated toxicity. Alternatively, combining CAR therapy with antibodies (e.g., anti-IL-6, anti-PD1, and anti-VEGF) or oncolytic viruses has enhanced CAR cell infiltration into GBM tumors and provided proinflammatory signals to the TME. CAR T- or NK-cells secreting cytokines (e.g., IL-12, IL-15, and IL-18) have shown improved efficacy within multiple GBM subtypes. Likewise, expressing cytokine-modulating receptors in CAR cells that promote or inhibit cytokine signaling has enhanced their activity. Finally, gene editing approaches are actively being pursued to directly influence immune signaling pathways in CAR cells. In this review, we summarize these cytokine modification methods and highlight any existing gaps in the hope of catalyzing an improved generation of CAR-based therapies for glioblastoma.

CRISPR/Cas9 system: recent applications in immuno-oncology and cancer immunotherapy

Clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) is essentially an adaptive immunity weapon in prokaryotes against foreign DNA. This system inspires the development of genome-editing technology in eukaryotes. In biomedicine research, CRISPR has offered a powerful platform to establish tumor-bearing models and screen potential targets in the immuno-oncology field, broadening our insights into cancer genomics. In translational medicine, the versatile CRISPR/Cas9 system exhibits immense potential to break the current limitations of cancer immunotherapy, thereby expanding the feasibility of adoptive cell therapy (ACT) in treating solid tumors. Herein, we first explain the principles of CRISPR/Cas9 genome editing technology and introduce CRISPR as a tool in tumor modeling. We next focus on the CRISPR screening for target discovery that reveals tumorigenesis, immune evasion, and drug resistance mechanisms. Moreover, we discuss the recent breakthroughs of genetically modified ACT using CRISPR/Cas9. Finally, we present potential challenges and perspectives in basic research and clinical translation of CRISPR/Cas9. This review provides a comprehensive overview of CRISPR/Cas9 applications that advance our insights into tumor-immune interaction and lay the foundation to optimize cancer immunotherapy.

A Rare Skeletal Disorder, Fibrous Dysplasia: A Review of Its Pathogenesis and Therapeutic Prospects

Fibrous dysplasia (FD) is a rare, non-hereditary skeletal disorder characterized by its chronic course of non-neoplastic fibrous tissue buildup in place of healthy bone. A myriad of factors have been associated with its onset and progression. Perturbation of cell-cell signaling networks and response outputs leading to disrupted building blocks, incoherent multi-level organization, and loss of rigid structural motifs in mineralized tissues are factors that have been identified to participate in FD induction. In more recent years, novel insights into the unique biology of FD are transforming our understandings of its pathology, natural discourse of the disease, and treatment prospects. Herein, we built upon existing knowledge with recent findings to review clinical, etiologic, and histological features of FD and discussed known and potential mechanisms underlying FD manifestations. Subsequently, we ended on a note of optimism by highlighting emerging therapeutic approaches aimed at either halting or ameliorating disease progression.

New Strategy for Promoting Vascularization in Tumor Spheroids in a Microfluidic Assay

Previous studies have developed vascularized tumor spheroid models to demonstrate the impact of intravascular flow on tumor progression and treatment. However, these models have not been widely adopted so the vascularization of tumor spheroids in vitro is generally lower than vascularized tumor tissues in vivo. To improve the tumor vascularization level, a new strategy is introduced to form tumor spheroids by adding fibroblasts (FBs) sequentially to a pre-formed tumor spheroid and demonstrate this method with tumor cell lines from kidney, lung, and ovary cancer. Tumor spheroids made with the new strategy have higher FB densities on the periphery of the tumor spheroid, which tend to enhance vascularization. The vessels close to the tumor spheroid made with this new strategy are more perfusable than the ones made with other methods. Finally, chimeric antigen receptor (CAR) T cells are perfused under continuous flow into vascularized tumor spheroids to demonstrate immunotherapy evaluation using vascularized tumor-on-a-chip model. This new strategy for establishing tumor spheroids leads to increased vascularization in vitro, allowing for the examination of immune, endothelial, stromal, and tumor cell responses under static or flow conditions.

A review on CRISPR/Cas: a versatile tool for cancer screening, diagnosis, and clinic treatment

Cancer is one of the leading causes of death worldwide and it has the trend of increase incidence. However, in the past decades, as quickly developed new technologies and modified old techniques for cancer screening, diagnosis, and treatment, the cancer-caused mortality rates dropped quickly, and the survival times of cancer patients are enhanced. However, the current death rate is still about 50% and the survival patients always suffer from the side effect of current cancer treatments. Recently developed Nobel Prize-winning CRISPR/Cas technology provides new hope on cancer screening, early diagnosis, and clinic treatment as well as new drug development. Currently, four major CRISPR/Cas9-derived genome editors, CRISPR/Cas9 nucleotide sequence editor, CRISPR/Cas base editor (BE), CRISPR prime editor (PE), and CRISPR interference (CRISPRi) (including both CRISPRa and CRISPRr), were well developed and used to various research and applications, including cancer biology study and cancer screening, diagnosis, and treatment. Additionally, CRISPR/Cas12 and CRISPR/Cas13 genome editors were also widely used in cancer-related basic and applied research as well as treatment. Cancer-associated SNPs and genetic mutations as well as both oncogenes and tumor suppressor genes are perfect targets for CRISPR/Cas-based gene therapy for cancer treatment. CRISPR/Cas is also employed to modify and generate new Chimeric antigen receptor (CAR) T-cells for improving its safety, efficiency, and longer-time last for treating various cancers. Currently, there are many clinic trails of CRISPR-based gene therapy for cancer treatments. Although all CRISPR/Cas-derived genome and epigenome tools are promising methods for cancer biology study and treatment, the efficiency and long term-safety are still the major concerns for CRISPR-based gene therapy. Developing new CRISPR/Cas delivery methods and reducing the potential side effects, including off-target impacts, will enhance CRISPR/Cas application in cancer-related research, diagnosis, and therapeutical treatment.

Evaluation of the Elements of Short Hairpin RNAs in Developing shRNA-Containing CAR T Cells

Short hairpin RNAs (shRNAs) have emerged as a powerful tool for gene knockdown in various cellular systems, including chimeric antigen receptor (CAR) T cells. However, the elements of shRNAs that are crucial for their efficacy in developing shRNA-containing CAR T cells remain unclear. In this study, we evaluated the impact of different shRNA elements, including promoter strength, orientation, multiple shRNAs, self-targeting, and sense and antisense sequence composition on the knockdown efficiency of the target gene in CAR T cells. Our findings highlight the importance of considering multiple shRNAs and their orientation to achieve effective knockdown. Moreover, we demonstrate that using a strong promoter and avoiding self-targeting can enhance CAR T cell functionality. These results provide a framework for the rational design of CAR T cells with shRNA-mediated knockdown capabilities, which could improve the therapeutic efficacy of CAR T cell-based immunotherapy.

Does Cytokine-Release Syndrome Induced by CAR T-Cell Treatment Have an Impact on the Pharmacokinetics of Meropenem and Piperacillin/Tazobactam in Patients with Hematological Malignancies? Findings from an Observational Case-Control Study

Chimeric antigen receptor (CAR) T-cell therapy is a promising approach for some relapse/refractory hematological B-cell malignancies; however, in most patients, cytokine release syndrome (CRS) may occur. CRS is associated with acute kidney injury (AKI) that may affect the pharmacokinetics of some beta-lactams. The aim of this study was to assess whether the pharmacokinetics of meropenem and piperacillin may be affected by CAR T-cell treatment. The study included CAR T-cell treated patients (cases) and oncohematological patients (controls), who were administered 24-h continuous infusion (CI) meropenem or piperacillin/tazobactam, optimized by therapeutic drug monitoring, over a 2-year period. Patient data were retrospectively retrieved and matched on a 1:2 ratio. Beta-lactam clearance (CL) was calculated as CL = daily dose/infusion rate. A total of 38 cases (of whom 14 and 24 were treated with meropenem and piperacillin/tazobactam, respectively) was matched with 76 controls. CRS occurred in 85.7% (12/14) and 95.8% (23/24) of patients treated with meropenem and piperacillin/tazobactam, respectively. CRS-induced AKI was observed in only 1 patient. CL did not differ between cases and controls for both meropenem (11.1 vs. 11.7 L/h, p = 0.835) and piperacillin (14.0 vs. 10.4 L/h, p = 0.074). Our findings suggest that 24-h CI meropenem and piperacillin dosages should not be reduced a priori in CAR T-cell patients experiencing CRS.

CAR-T cell therapy followed by allogenic hematopoietic stem cell transplantation yielded comparable outcome between Ph like ALL and other high-risk ALL

It was previously believed that patients with Ph-like ALL had poorer prognosis compared with other B-ALL subgroups due to resistance to conventional chemotherapy and lack of targeted drugs. CAR-T therapy has been successfully applied in the treatment of relapsed and refractory B-ALL. Currently, there are few data on whether CAR-T therapy can alter the outcome of Ph-like ALL. Here we included 17 Ph-like, 23 Ph+ and 51 other B-ALL patients, who received autologous CAR T-cell therapy and subsequently allogenic stem cell transplantation. Patients in the Ph-like group and B-ALL-others group were younger that those in the Ph+ group (P=0.001). Ph-like and Ph+ ALL patients showed higher white blood cell counts at diagnosis (P=0.025). The percentage of patients with active disease before receiving CAR T-cells infusion was 64.7%, 39.1% and 62.7% in the Ph-like, Ph+ and B-ALL-others groups. The response rates to CAR-T therapy were 94.1% (16/17), 95.6% (22/23) and 98.0% (50/51) in the Ph-like, Ph+ and B-ALL-others groups. Measurable residual disease negative CR was achieved in 64.7% (11/17), 60.9% (14/23) and 54.9% (28/51) in the Ph-like, Ph+ and B-ALL-others groups, respectively. The estimated rates of 3-year overall survival (65.9%±16.5%, 59.7%±10.5% and 61.6%±7.3%, P=0.758) and 3-year relapse-free survival (59.8%±14.8%, 63.1%±10.5% and 56.3%±7.1%, P=0.764) were comparable among the Ph-like, Ph+ and B-ALL-others groups. Estimated 3-year cumulative relapse rate was 7.8%±0.6%, 23.4%±0.9% and 29.0%±0.4% (P=0.241). Our findings suggest that CART followed by allo-HSCT results in a comparable prognosis in Ph-like ALL and other high-risk B-ALL.Trial registration ClinicalTrials. gov, NCT03275493, Registered on September 7, 2017, prospectively registered and NCT03614858, Registered on August 3, 2018, prospectively registered.

RNA Therapeutics for Improving CAR T-cell Safety and Efficacy

Autologous chimeric antigen receptor (CAR) T cells have recently emerged as potent tools in the fight against cancer, with promising therapeutic efficacy against hematological malignancies. However, several limitations hamper their widespread clinical use, including availability of target antigen, severe toxic effects, primary and secondary resistance, heterogeneous quality of autologous T cells, variable persistence, and low activity against solid tumors. Development of allogeneic off-the-shelf CAR T cells could help address some of these limitations but is impeded by alloimmunity with either rejection and limited expansion of allo-CAR T cells or CAR T cells versus host reactions. RNA therapeutics, such as small interfering RNAs, microRNAs, and antisense oligonucleotides, are able to silence transcripts in a sequence-specific and proliferation-sensitive way, which may offer a way to overcome some of the challenges facing CAR T-cell development and clinical utility. Here, we review how different RNA therapeutics or a combination of RNA therapeutics and genetic engineering could be harnessed to improve the safety and efficacy of autologous and allogeneic CAR T-cell therapy.

Evaluating the Patient with Neurotoxicity after Chimeric Antigen Receptor T-cell Therapy

OPINION STATEMENT

Chimeric antigen receptor (CAR) T-cells are now a well-established treatment for hematologic malignancies. Their use in clinical practice has expanded quite rapidly and hospitals have developed CAR T-cell protocols to evaluate patients for associated toxicities, and particularly for neurotoxicity. There are many variables that influence the risk for developing this complication, many of which are not fully understood. The severity can be related to a particular product. Clinical vigilance is critical to facilitate early recognition of neurotoxicity, hence the importance of pre-CAR T-cell neurological evaluation of each patient. While details of such an evaluation may slightly differ between institutions, generally a comprehensive neurological evaluation including assessment of cognitive abilities along with magnetic resonance imaging (MRI) of the brain is a gold standard. Management of neurotoxicity requires a well-orchestrated team approach with specialists from oncology, neurology, oftentimes neurosurgery and neuro-intensive care. Diagnostic work-up frequently includes detailed neurologic evaluation with comparison to the baseline assessment, imaging of the brain, electroencephalogram, and lumbar puncture. While steroids are uniformly used for treatment, many patients also receive tocilizumab for an underlying and frequently concomitant cytokine release syndrome (CRS) in addition to symptom-driven supportive care. Novel CAR T-cell constructs and other agents allowing for potentially lower risk of toxicity are being explored. While neurotoxicity is predominantly an early, and reversible, event, a growing body of literature suggests that late neurotoxicity with variable clinical presentation can also occur.

Pre-clinical efficacy of CD20-targeted chimeric antigen receptor T cells for non-Hodgkin's lymphoma

BACKGROUND

A 4-1BB/CD3-ζ-costimulated CAR-T against CD20 (CAR-T20) was subjected to a systemic efficacy evaluation in a cell co-culture model, and NOD-SCID IL-2 receptor gamma null mice (short for NSG mice) were xenografted with human Burkitt's lymphoma Raji cells.

METHODS

CAR-T20 cells were incubated with target cells (K562, K562 CD20 or Raji cells) at ratios of 10:1 and 5:1 for 24 h, and the killing rate was estimated by an LDH cytotoxicity assay. To evaluate the effect of CAR-T20 on the survival time of tumor-bearing animals, 30 NSG mice were employed, and Raji-Luc cells (5 × 10⁵ cells per mouse) were administered prior to CAR-T20 administration. The survival time, optical intensity of Raji-Luc cells, clinical symptoms, and body mass of the animals were observed. Another 144 male NSG mice were employed to investigate the proliferation and antitumor effects of CAR-T20. Human cytokine and murine cytokines were detected at 1, 7, 14, 21, 28, 42, 56 and 90 days post-CAR-T administration, while biochemistry index analysis, T-cell and CAR-T-cell detection in peripheral blood, and histopathological examination were performed at 14, 28, 56 and 90 days post-administration.

RESULTS

CAR-T20 cells had a specific killing effect on CD20-expressing cells in vitro. At a dose of 1 × 10⁶ per mouse or above, CAR-T20 prolonged the median survival time from 14 days to more than 3 months, inhibited the proliferation of Raji cells in mice, and alleviated the clinical manifestations and weight loss caused by the Raji-Luc cell load. CAR-T20 at a dose of 2 × 10⁶ per mouse or above inhibited the proliferation of Raji cells in mice for up to 111 days post-administration without recurrence. The numbers of T cells and CAR-T cells in the animals administered CAR-T20 increased significantly when Raji cells were markedly proliferated and subsequently decreased when Raji cells were predominantly inhibited. CAR-T20 increased human IFN-γ, murine TNF and murine IL-6 levels and decreased human IL-10 levels in tumor-bearing mice. The incidences of xenografted tumors in organs/tissues were also reduced effectively by CAR-T20.

CONCLUSION

The effective dose of CAR-T20 in mice starts from 1 × 10⁶ per mouse, equivalent to a clinical dose of 5 × 10⁶/kg. Together, our data support the clinical translation of CAR-T20 for R/R B-cell NHL patients.

Investigation of the risk factors to predict cytokine release syndrome in relapsed or refractory B-cell acute lymphoblastic leukemia patients receiving IL-6 knocking down anti-CD19 chimeric antigen receptor T-cell therapy

CD19 chimeric antigen receptor-T (CAR-T) cell therapy has achieved remarkable results in patients with relapsed or refractory B-cell acute lymphoblastic leukemia (r/r B-ALL). However, the cytokine release syndrome (CRS) was presented in most patients as common toxicity and severe CRS (sCRS) characterized by the sharp increase in interleukin-6 (IL-6) could be life-threatening. We conducted a phase II clinical trial of ssCAR-T-19 cells, anti-CD19 CAR-T cells with shRNA targeting IL-6, in 61 patients with r/r B-ALL. This trial was registered at www.clinicaltrials.gov as #NCT03275493. Fifty-two patients achieved CR while nine patients were considered NR. The median duration of response (DOR) and overall survival (OS) were not reached (>50 months). CRS developed in 81.97% of patients, including 54.10% with grades 1 to 2 (grade 1, 31.15%; grade 2, 22.95%) and 27.87% with grades 3 to 4 (grade 3, 26.23%; grade 4, 1.64%). sCRS occurs earlier than mild CRS (mCRS). A multivariable analysis of baseline characteristics identified high bone marrow disease burden and poor genetic risk before infusion as independent risk factors for sCRS. After infusion, patients with sCRS exhibited larger expansion of ssCAR-T-19 cells, higher peak levels of IL-6, IL-10, and IFN-γ, and suffered more severe hematological and non-hematological toxicities compared with those with mCRS.

Lipid nanoparticles produce chimeric antigen receptor T cells with interleukin-6 knockdown in vivo

Chimeric receptor T cells (CAR-T) can effectively cure leukemia; however, there are two limitations: a complicated preparation process ex vivo and cytokine release syndrome (CRS). In this study, we constructed a lipid nanoparticle system modified by CD3 antibody on the surface, loading with the plasmid containing the combination gene of interleukin 6 short hairpin RNA (IL-6 shRNA) and CD19-CAR (AntiCD3-LNP/CAR19 + shIL6). The system targeted T cells by the mediation of CD3 antibody and stably transfected T cells to transform them into CAR-T cells with IL-6 knockdown, thus killing CD19-highly expressed leukemia tumor cells and reducing CRS caused by IL-6. In vivo experiments showed that AntiCD3-LNP/CAR19 + shIL6 could stably transfect T cells and produce CAR-T within 90 days to kill the tumor. This significantly prolonged the survival time of leukemia model mice and demonstrated the prepared LNP exhibited the same anti-tumor effect as the traditional CAR-T cells prepared ex vivo. In this study, CAR-T cells were directly produced in vivo after intravenous injection of the lipid nanoparticles, without the need of using the current complex process ex vivo. Additionally, IL-6 expression was silenced, which would be helpful to reduce the CRS and improve the safety of CAR-T therapy. This method improves the convenience of using CAR-T technology and is helpful in further promoting the clinical application of CAR-T.

Feasibility of in vivo CAR T cells tracking using streptavidin-biotin-paired positron emission tomography

BACKGROUND

A novel reporter system, streptavidin (SA)- [⁶⁸ Ga]Ga-labeled biotin ([⁶⁸ Ga]Ga-DOTA-biotin), was constructed and its ability for PET imaging the behaviors of CAR T cells were also evaluated in this study.

METHODS

In vitro activity and cytotoxicity of the SA transduced anti-CD19-CAR T (denoted as SA-CD19-CAR T) cells were determined. The feasibility of monitoring proliferation profiles of SA-CD19-CAR T cells using [⁶⁸ Ga]Ga-DOTA-biotin was firstly investigated in a solid tumor model. Also, the pharmacodynamics and pharmacokinetics of the CAR T cells in whole-body hematologic neoplasms were evaluated by bioluminescence imaging and [⁶⁸ Ga]Ga-DOTA-biotin PET imaging simultaneously.

RESULTS

After transduction with SA, the activity and cytotoxicity of the modified CAR T cells were not affected. PET images revealed that the uptakes of [⁶⁸ Ga]Ga-DOTA-biotin in CD19⁺ K562 solid tumors were 0.67 ± 0.32 ID%/g and 1.26 ± 0.13 ID%/g at 30 min and 96 h p.i. after administration of SA-CD19-CAR T cells respectively. It confirmed that the SA-CD19-CAR T cells could effectively inhibit the growth of Raji hematologic tumors. However, low radioactivity related to the proliferation of CD19-CAR T cells was detected in the Raji model.

CONCLUSION

SA-CD19-CAR T cells were constructed successfully without disturbing the antitumor functions of the cells. The proliferation of the CAR T cells in solid tumors could be early detected by [⁶⁸ Ga]Ga-DOTA-biotin PET imaging.

Anti-CD19 and anti-BCMA CAR T cell therapy followed by lenalidomide maintenance after autologous stem-cell transplantation for high-risk newly diagnosed multiple myeloma

Few prospective studies have examined posttransplant chimeric antigen receptor (CAR) T cell infusion as candidates for front-line consolidation therapy for high-risk multiple myeloma (MM) patients. This single-arm exploratory clinical trial is the first to evaluate the safety and efficacy of sequential anti-CD19 and anti-BCMA CAR-T cell infusion, followed by lenalidomide maintenance after autologous stem cell transplantation (ASCT), in 10 high-risk newly diagnosed multiple myeloma (NDMM) patients. The treatment was generally well tolerated, with hematologic toxicities being the most common grade 3 or higher adverse events. All patients had cytokine release syndrome (CRS), which was grade 1 in 5 patients (50%) and grade 2 in 5 patients (50%). No neurotoxicity was observed after CAR-T cell infusion. The overall response rate was 100%, with the best response being 90% for a stringent complete response (sCR), and 10% for a complete response (CR). At a median follow-up of 42 (36-49) months, seven (70%) of 10 patients showed sustained minimal residual disease (MRD) negativity for more than 2 years. The median progression-free survival (PFS) and overall survival (OS) were not reached. Although the sample size was small and there was a lack of control in this single-arm study, the clinical benefits observed warrant ongoing randomized controlled trials.

c-Met specific CAR-T cells as a targeted therapy for non-small cell lung cancer cell A549

Non-small cell lung cancer (NSCLC) is considered to be one of the most prevalent and fatal malignancies, with a poor survival rate. Chimeric antigen receptor T cell (CAR-T) cell therapy is one of the most exciting directions in the field of Cellular immunotherapy. Therefore, CAR-T cells that target c-Met have been developed for use in NSCLC therapy and might be a potential therapeutic strategy. The anti c-Met ScFv structure was fused with the transmembrane and intracellular domains. Using a lentiviral vector to load the c-Met CAR gene, then transfected the c-Met CAR lentiviral into human T cells to obtain the second generation c-Met CAR-T expressing CARs stably. In vitro co-culture, experiments revealed that CAR-T cells have high proliferative activity and the potential to secrete cytokines (IL-2, TNF-α, and IFN-γ). c-Met CAR-T cells showed special cellular cytotoxicity in LDH release assay. A subcutaneous tumor model in nude mice was used to test the anticancer effectiveness of c-Met CAR-T cells in vivo. For c-Met positive NSCLC tissue, according to tumor volume, weight, fluorescence intensity, and immunohistochemical detection, c-Met CAR-T cells had stronger tumor growth suppression compared to untransduced T cells. HE staining revealed that c-Met CAR-T cells did not produced side effects in nude mice. Taken together, we provided useful method to generate c-Met CAR- T cells, which exhibit enhanced cytotoxicity against NSCLC cells in vitro and in vivo. Thus, providing a new therapeutic avenue for treating NSCLC clinically.

Highlights

(1) c-Met CAR-T capable of stably expressing c-Met CARs were constructed.

(2) c-Met CAR-T have strong anti-tumor ability and proliferation ability in vitro.

(3) c-Met CAR-T can effectively inhibit the growth of A549 cells subcutaneous xenografts.

Human induced-T-to-natural killer cells have potent anti-tumour activities

BACKGROUND

Adoptive cell therapy (ACT) is a particularly promising area of cancer immunotherapy, engineered T and NK cells that express chimeric antigen receptors (CAR) are being explored for treating hematopoietic malignancies but exhibit limited clinical benefits for solid tumour patients, successful cellular immunotherapy of solid tumors demands new strategies.

METHODS

Inactivation of BCL11B were performed by CRISPR/Cas9 in human T cells. Immunophenotypic and transcriptional profiles of sgBCL11B T cells were characterized by cytometer and transcriptomics, respectively. sgBCL11B T cells are further engineered with chimeric antigen receptor. Anti-tumor activity of ITNK or CAR-ITNK cells were evaluated in preclinical and clinical studies.

RESULTS

We report that inactivation of BCL11B in human CD8⁺ and CD4⁺ T cells induced their reprogramming into induced T-to-natural killer cells (ITNKs). ITNKs contained a diverse TCR repertoire; downregulated T cell-associated genes such as TCF7 and LEF1; and expressed high levels of NK cell lineage-associated genes. ITNKs and chimeric antigen receptor (CAR)-transduced ITNKs selectively lysed a variety of cancer cells in culture and suppressed the growth of solid tumors in xenograft models. In a preliminary clinical study, autologous administration of ITNKs in patients with advanced solid tumors was well tolerated, and tumor stabilization was seen in six out nine patients, with one partial remission.

CONCLUSIONS

The novel ITNKs thus may be a promising novel cell source for cancer immunotherapy.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03882840 . Registered 20 March 2019-Retrospectively registered.

Engineering the next-generation of CAR T-cells with CRISPR-Cas9 gene editing

Chimeric Antigen Receptor (CAR) T-cells represent a breakthrough in personalized cancer therapy. In this strategy, synthetic receptors comprised of antigen recognition, signaling, and costimulatory domains are used to reprogram T-cells to target tumor cells for destruction. Despite the success of this approach in refractory B-cell malignancies, optimal potency of CAR T-cell therapy for many other cancers, particularly solid tumors, has not been achieved. Factors such as T-cell exhaustion, lack of CAR T-cell persistence, cytokine-related toxicities, and bottlenecks in the manufacturing of autologous products have hampered the safety, effectiveness, and availability of this approach. With the ease and accessibility of CRISPR-Cas9-based gene editing, it is possible to address many of these limitations. Accordingly, current research efforts focus on precision engineering of CAR T-cells with conventional CRISPR-Cas9 systems or novel editors that can install desired genetic changes with or without introduction of a double-stranded break (DSB) into the genome. These tools and strategies can be directly applied to targeting negative regulators of T-cell function, directing therapeutic transgenes to specific genomic loci, and generating reproducibly safe and potent allogeneic universal CAR T-cell products for on-demand cancer immunotherapy. This review evaluates several of the ongoing and future directions of combining next-generation CRISPR-Cas9 gene editing with synthetic biology to optimize CAR T-cell therapy for future clinical trials toward the establishment of a new cancer treatment paradigm.

The differential effects of tumor burdens on predicting the net benefits of ssCART-19 cell treatment on r/r B-ALL patients

The tumor burden (TB) is significantly related to the severity of cytokine release syndrome (CRS) caused by CAR-T cells, but its correlation with therapeutic efficacy has not been systematically studied. This study focused on the effects of the TB level on both the safety and efficacy of ssCART-19 as a treatment for r/r B-ALL. Taking the 5% tumor burden as the boundary, the study participants were divided into 2 groups, high and low tumor burden groups. Under this grouping strategy, the impacts of differential r/r B-ALL TBs on the clinical therapeutic efficacy (CR rate and long-term survival) and safety profiles after ssCART-19 cell treatment were analysed. 78 patients were reported in this study. The differential B-ALL TBs significantly affected the complete remission (CR) rates of patients treated with ssCART-19, with rates of 93.94% and 75.56% in the low and high TB groups, respectively (P = 0.0358). The effects of TBs on long-term therapeutic efficacy were further studied based on event-free survival (EFS) and overall survival (OS) profiles; both the OS and EFS of the low TB group were better than those of the high TB group, but the differences were not statistically significant. Importantly, the time points of TB measurement did not significantly affect the OS and EFS profiles regardless of whether the TBs were measured before or after fludarabine-cyclophosphamide (FC) preconditional chemotherapy. On the other hand, the severity of CRS was significantly correlated with the TB level (P = 0.0080), and the incidence of sCRS was significantly related to the TB level (the sCRS incidence increased as the TB level increased, P = 0.0224). Unexpectedly, the ssCART-19 cell expansion peaks were not significantly different (P = 0.2951) between the study groups. Patients with a low r/r B-ALL TB yield more net benefits from CAR-T treatment than those with a high TB in terms of safety and CR rate. These findings are critical and valuable for determining the optimal CAR-T cell treatment window for r/r B-ALL patients and will further the development of comprehensive and reasonable CAR-T cell treatment plans for r/r B-ALL patients with differential TBs.Trial registration: ClinicalTrials.gov identifier, NCT03919240.

Mechanisms of immune effector cell-associated neurotoxicity syndrome after CAR-T treatment

Chimeric antigen receptor T-cell (CAR-T) treatment has revolutionized the landscape of cancer therapy with significant efficacy on hematologic malignancy, especially in relapsed and refractory B cell malignancies. However, unexpected serious toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) still hamper its broad application. Clinical trials using CAR-T cells targeting specific antigens on tumor cell surface have provided valuable information about the characteristics of ICANS. With unclear mechanism of ICANS after CAR-T treatment, unremitting efforts have been devoted to further exploration. Clinical findings from patients with ICANS strongly indicated existence of overactivated peripheral immune response followed by endothelial activation-induced blood-brain barrier (BBB) dysfunction, which triggers subsequent central nervous system (CNS) inflammation and neurotoxicity. Several animal models have been built but failed to fully replicate the whole spectrum of ICANS in human. Hopefully, novel and powerful technologies like single-cell analysis may help decipher the precise cellular response within CNS from a different perspective when ICANS happens. Moreover, multidisciplinary cooperation among the subjects of immunology, hematology, and neurology will facilitate better understanding about the complex immune interaction between the peripheral, protective barriers, and CNS in ICANS. This review elaborates recent findings about ICANS after CAR-T treatment from bed to bench, and discusses the potential cellular and molecular mechanisms that may promote effective management in the future. This article is categorized under: Cancer > Biomedical Engineering Immune System Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology.

Mechanisms of cytokine release syndrome and neurotoxicity of CAR T-cell therapy and associated prevention and management strategies

Chimeric antigen receptor (CAR) T-cell therapy has yielded impressive outcomes and transformed treatment algorithms for hematological malignancies. To date, five CAR T-cell products have been approved by the US Food and Drug Administration (FDA). Nevertheless, some significant toxicities pose great challenges to the development of CAR T-cell therapy, most notably cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Understanding the mechanisms underlying these toxicities and establishing prevention and treatment strategies are important. In this review, we summarize the mechanisms underlying CRS and ICANS and provide potential treatment and prevention strategies.

Optimizing the Clinical Impact of CAR-T Cell Therapy in B-Cell Acute Lymphoblastic Leukemia: Looking Back While Moving Forward

Chimeric antigen receptor T-cell (CAR-T) therapy has been successful in creating extraordinary clinical outcomes in the treatment of hematologic malignancies including relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). With several FDA approvals, CAR-T therapy is recognized as an alternative treatment option for particular patients with certain conditions of B-ALL, diffuse large B-cell lymphoma, mantle cell lymphoma, follicular lymphoma, or multiple myeloma. However, CAR-T therapy for B-ALL can be surrounded by challenges such as various adverse events including the life-threatening cytokine release syndrome (CRS) and neurotoxicity, B-cell aplasia-associated hypogammaglobulinemia and agammaglobulinemia, and the alloreactivity of allogeneic CAR-Ts. Furthermore, recent advances such as improvements in media design, the reduction of ex vivo culturing duration, and other phenotype-determining factors can still create room for a more effective CAR-T therapy in R/R B-ALL. Herein, we review preclinical and clinical strategies with a focus on novel studies aiming to address the mentioned hurdles and stepping further towards a milestone in CAR-T therapy of B-ALL.

From Hematopoietic Stem Cell Transplantation to Chimeric Antigen Receptor Therapy: Advances, Limitations and Future Perspectives

Chimeric antigen receptor (CAR) T-cell therapy was envisioned as a mechanism to re-direct effector T-cells to eliminate tumor cells. CARs are composed of the variable region of an antibody that binds a native cancer antigen coupled to the signaling domain of a TCR and co-stimulatory molecules. Its success and approval by the U.S. Food and Drug Administration for the treatment of B-cell malignancies revolutionized the immunotherapy field, leading to extensive research on its possible application for other cancer types. In this review, we will focus on the evolution of CAR-T cell therapy outlining current technologies as well as major obstacles for its wide application. We will highlight achievements, the efforts to increase efficacy and to evolve into an off-the-shelf treatment, and as a possible future treatment for non-cancer related diseases.

Signaling pathways in the regulation of cytokine release syndrome in human diseases and intervention therapy

Cytokine release syndrome (CRS) embodies a mixture of clinical manifestations, including elevated circulating cytokine levels, acute systemic inflammatory symptoms and secondary organ dysfunction, which was first described in the context of acute graft-versus-host disease after allogeneic hematopoietic stem-cell transplantation and was later observed in pandemics of influenza, SARS-CoV and COVID-19, immunotherapy of tumor, after chimeric antigen receptor T (CAR-T) therapy, and in monogenic disorders and autoimmune diseases. Particularly, severe CRS is a very significant and life-threatening complication, which is clinically characterized by persistent high fever, hyperinflammation, and severe organ dysfunction. However, CRS is a double-edged sword, which may be both helpful in controlling tumors/viruses/infections and harmful to the host. Although a high incidence and high levels of cytokines are features of CRS, the detailed kinetics and specific mechanisms of CRS in human diseases and intervention therapy remain unclear. In the present review, we have summarized the most recent advances related to the clinical features and management of CRS as well as cutting-edge technologies to elucidate the mechanisms of CRS. Considering that CRS is the major adverse event in human diseases and intervention therapy, our review delineates the characteristics, kinetics, signaling pathways, and potential mechanisms of CRS, which shows its clinical relevance for achieving both favorable efficacy and low toxicity.

Genetic Modification of Cytokine Signaling to Enhance Efficacy of CAR T Cell Therapy in Solid Tumors

Chimeric antigen receptor (CAR) T cell therapy has shown unprecedented success in treating advanced hematological malignancies. Its effectiveness in solid tumors has been limited due to heterogeneous antigen expression, a suppressive tumor microenvironment, suboptimal trafficking to the tumor site and poor CAR T cell persistence. Several approaches have been developed to overcome these obstacles through various strategies including the genetic engineering of CAR T cells to blunt the signaling of immune inhibitory receptors as well as to modulate signaling of cytokine/chemokine molecules and their receptors. In this review we offer our perspective on how genetically modifying cytokine/chemokine molecules and their receptors can improve CAR T cell qualities such as functionality, persistence (e.g. resistance to pro-apoptotic signals) and infiltration into tumor sites. Understanding how such modifications can overcome barriers to CAR T cell effectiveness will undoubtedly enhance the potential of CAR T cells against solid tumors.

Pharmacokinetic and pharmacodynamic studies of CD19 CAR T cell in human leukaemic xenograft models with dual-modality imaging

In recent years, chimeric antigen receptor T (CAR T)-cell therapy has shown great potential in treating haematologic disease, but no breakthrough has been achieved in solid tumours. In order to clarify the antitumour mechanism of CAR T cell in solid tumours, the pharmacokinetic (PK) and pharmacodynamic (PD) investigations of CD19 CAR T cell were performed in human leukaemic xenograft mouse models. For PK investigation, we radiolabelled CD19 CAR T cell with ⁸⁹ Zr and used PET imaging in the CD19-positive and the CD19-negative K562-luc animal models. For PD evaluation, optical imaging, tumour volume measurement and DNA copy-number detection were performed. Unfortunately, the qPCR results of the DNA copy number in the blood were below the detection limit. The tumour-specific uptake was higher in the CD19-positive model than in the CD19-negative model, and this was consistent with the PD results. The preliminary PK and PD studies of CD19 CAR T cell in solid tumours are instructive. Considering the less efficiency of CAR T-cell therapy of solid tumours with the limited number of CAR T cells entering the interior of solid tumours, this study is suggestive for the subsequent CAR T-cell design and evaluation of solid tumour therapy.

Toci or not toci: innovations in the diagnosis, prevention, and early management of cytokine release syndrome

Cytokine release syndrome (CRS) remains a significant toxicity of chimeric antigen receptor T-cell (CAR-T) therapy for hematologic malignancies. While established guidelines exist for the management of Grade 2+ CRS with immunosuppressive agents such as tocilizumab or corticosteroids, the management of early-grade CRS (i.e. Grade 1 CRS with isolated fevers) has no such consensus beyond supportive care. In this review, we discuss early-grade CRS with an emphasis on its diagnosis, management, and prevention. Strategies to target early-grade CRS include immunosuppression preemptively (once CRS develops) or prophylactically (before CRS develops) as well as novel small-molecule inhibitors or fractionated CAR-T dosing. In the near future, next-generation CAR-T therapies may be able to target CRS precisely or obviate CRS entirely. If shown to prevent CRS-associated morbidity while maintaining therapeutic anti-neoplastic efficacy, these innovative strategies will enhance the safety of CAR-T therapy while also improving its operationalization and accessibility in the real-world setting.

CAR-T Cell Therapy: Mechanism, Management, and Mitigation of Inflammatory Toxicities

Engineered T cell therapies such as chimeric antigen receptor (CAR) expressing T cells (CAR-T cells) have great potential to treat many human diseases; however, inflammatory toxicities associated with these therapies present safety risks and can greatly limit its widespread use. This article briefly reviews our current understanding of mechanisms for inflammatory toxicities during CAR T-cell therapy, current strategies for management and mitigation of these risks and highlights key areas of knowledge gap for future research.

Early Time-to-Tocilizumab after B Cell Maturation Antigen-Directed Chimeric Antigen Receptor T Cell Therapy in Myeloma

Preemptive administration of tocilizumab (toci) to manage cytokine release syndrome (CRS) after chimeric antigen receptor T cell (CAR-T) therapy may reduce rates of serious CRS but conversely may worsen neurotoxicity or risk of infections. Optimal toci administration strategies for patients with relapsed/refractory multiple myeloma (RRMM) receiving B cell maturation antigen (BCMA)-directed CAR-T therapies have not been evaluated. The objective of this study was to identify whether shorter time-to-toci intervals (hours between first fever attributed to CRS and first dose of toci) have any impact on therapy-related toxicities or clinical outcomes among patients with RRMM receiving BCMA-directed CAR-T therapies. We retrospectively analyzed our institution's experience with 4 BCMA-directed CAR-T therapies (idecabtagene vicleucel, bb21217, ciltacabtagene autoleucel, and orvacabtagene autoceucel) for RRMM over a 3-year period ending in June 2020. We divided patients based on the administration of toci and median time-to-toci interval into early-toci (time-to-toci ≤50th percentile), late-toci (time-to-toci >50th percentile), and no-toci (no toci received) groups. We compared the early-toci and late-toci groups with regard to patient characteristics, weight-based CAR-T toxicities, selected toxicities (CRS, neurotoxicity, macrophage activation syndrome, or infections), and clinical outcomes. Of 50 analyzed patients with a median follow-up of 15.3 months, 76% (n = 38) received ≥1 dose of toci (range, 1 to 3) and were classified into early-toci (time-to-toci ≤12 hours) or late-toci (time-to-toci >12 hours) groups. The 2 groups (n = 19 each) had similar CRS grade distributions, hours to CRS onset, CRS-related biomarkers, and incidences of neurotoxicity or severe infections; however, weight-adjusted CAR-T cell doses were higher in the early-toci group (median 5.99 versus 3.80 × 106 cells/kg, P < 0.01). Peak CRS grades (range, 0 to 2) using American Society for Transplantation and Cellular Therapy consensus criteria, neurotoxicity rates, and rates of severe infections were similar between groups; however, the median CRS duration was 18.6 hours for the early-toci group versus 84.7 hours for the late-toci group. The median progression-free survival was 35.7 months in the early-toci group and 13.2 months in the late-toci group. While limited by small sample size and known confounders such as CAR-T cell dose, our analysis suggests that preemptive toci strategies for CRS management with BCMA-directed CAR-T therapy-specifically, toci administration within 12 hours of the first fever attributed to CRS-do not appear to increase rates of therapy-related toxicities or compromise efficacy. However, total CRS duration may be shorter with early-toci workflows. Prospective validation of our findings may lead to improved safety and cost-effectiveness profiles for CAR-T therapy in RRMM.

Current and emerging therapies for primary central nervous system lymphoma

Primary central nervous system (CNS) lymphoma (PCNSL) is a rare type of extranodal lymphoma exclusively involving the CNS at the onset, with diffuse large B-cell lymphoma (DLBCL) as the most common histological subtype. As PCNSL is a malignancy arising in an immune-privileged site, suboptimal delivery of systemic agents into tumor tissues results in poorer outcomes in PCNSL than in non-CNS DLBCLs. Commonly used regimens for PCNSL include high-dose methotrexate-based chemotherapy with rituximab for induction therapy and intensive chemotherapy followed by autologous hematopoietic stem cell transplantation or whole-brain radiotherapy for consolidation therapy. Targeted agents against the B-cell receptor signaling pathway, microenvironment immunomodulation and blood-brain barrier (BBB) permeabilization appear to be promising in treating refractory/relapsed patients. Chimeric antigen receptor-T cells (CAR-T cells) have been shown to penetrate the BBB as a potential tool to manipulate this disease entity while controlling CAR-T cell-related encephalopathy syndrome. Future approaches may stratify patients according to age, performance status, molecular biomarkers and cellular bioinformation. This review summarizes the current therapies and emerging agents in clinical development for PCNSL treatment.

Robust Antitumor Activity and Low Cytokine Production by Novel Humanized Anti-CD19 CAR T Cells

Recent studies have described the remarkable clinical outcome of anti-CD19 chimeric antigen receptor (CAR) T cells in treating B-cell malignancies. However, over 50% of patients develop life-threatening toxicities associated with cytokine release syndrome which may limit its utilization in low-resource settings. To mitigate the toxicity, we designed a novel humanized anti-CD19 CAR T cells by humanizing the framework region of single-chain variable fragment (scFv) derived from a murine FMC63 mAb and combining it with CD8α transmembrane domain, 4-1BB costimulatory domain, and CD3ζ signaling domain (h1CAR19-8BBζ). Docking studies followed by molecular dynamics simulation revealed that the humanized anti-CD19 scFv (h1CAR19) establishes higher binding affinity and has a flexible molecular structure with CD19 antigen compared with murine scFv (mCAR19). Ex vivo studies with CAR T cells generated from healthy donors and patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) expressing either h1CAR19 or mCAR19 showed comparable antitumor activity and proliferation. More importantly, h1CAR19-8BBζ T cells produced lower levels of cytokines (IFNγ, TNFα) upon antigen encounter and reduced the induction of IL6 cytokine from monocytes than mCAR19-8BBζ T cells. There was a comparable proliferation of h1CAR19-8BBζ T cells and mCAR19-8BBζ T cells upon repeated antigen encounter. Finally, h1CAR19-8BBζ T cells efficiently eliminated NALM6 tumor cells in a preclinical model. In conclusion, the distinct structural modification in CAR design confers the novel humanized anti-CD19 CAR with a favorable balance of efficacy to toxicity providing a rationale to test this construct in a phase I trial.

Successful application of anti-CD19 CAR-T therapy with IL-6 knocking down to patients with central nervous system B-cell acute lymphocytic leukemia

Few studies have described chimeric antigen receptor–modified T cell (CAR-T) therapy for central nervous system (CNS) B-cell acute lymphocytic leukemia (B-ALL) patients due to life-threatening CAR-T-related encephalopathy (CRES) safety issues. In this study, CAR-Ts targeting CD19 with short hairpin RNA (shRNA)-IL-6 gene silencing technology (ssCART-19s) were prepared. We conducted a phase 1 clinical trial (ClinicalTrials.gov number, NCT03064269). Three patients with relapsed CNS B-ALL were enrolled, conditioned with the fludarabine and cyclophosphamide for lymphocyte depletion and infused with ssCART-19s for three consecutive days. Clinical symptoms and laboratory examinations were monitored. After ssCART-19 treatment, three patients' symptoms resolved almost entirely. Brain leukemic infiltration reduced significantly based on magnetic resonance imaging (MRI), and there were no leukemic blasts in cerebrospinal fluid (CSF), which was confirmed by cytological and molecular examinations. Additionally, increases in the levels of cytokines and immune cells were observed in the CSF of all patients. Only grade 1 cytokine release syndrome (CRS) manifesting as fever was noted in patients. In conclusion, CAR-Ts with shRNA-IL-6 gene knockdown migrated into the CNS, eradicated leukemic cells and elevated cytokines in CSF with mild, acceptable side effects.