Phase I Clinical Trial of CD19 CAR-T Cells Expressing CXCR5 Protein for the Treatment of Relapsed or Refractory B-cell Lymphoma.

BACKGROUND: It is difficult for CD19 CAR-T cells to enter solid tumors, which is one reason for their poor efficacy in lymphoma treatment. The chemokine CXCL13 secreted by stro-mal cells of the lymph nodes induces the homing of B and T lymphocytes, which express its receptor CXCR5. Preclinical trials have shown that the expression of CXCR5 on CD19 CAR-T cells can increase their migration to the tumor microenvironment and enhance their antitumor function. METHODS: We engineered the CD19 CAR-T cells to express a second receptor, CXCR5. Then, we conducted a phase I clinical trial to evaluate the safety and efficacy of CXCR5 CD19 CAR-T cells in the treatment of relapsed or refractory (R/R) B-cell lymphoma. RESULTS: We recruited 10 patients with R/R B-cell lymphoma undergoing CXCR5 CD19 CAR-T cell therapy. The objective response rate was 80%, and the complete response rate was 50%. The median follow-up time was 15.48 months (3.4-22.3 months), and the median Progression-Free Survival (PFS) time was 8.15 months (1.5-22.33 months). One patient received ASCT at 1.5 months (at PR) after infusion of CAR-T cells. The incidence of grade 1 and grade 2 Cytokine Release Syndrome (CRS) was 70% and 20%, respectively. No patient experienced grade 3 or higher levels of CRS, neurotoxicity, or infusion-related dose toxicity. CONCLUSION: The results obtained in this study suggest that CXCR5 CD19 CAR-T cells should be investigated in a trial with broader patient populations. TRIAL REGISTRATION: The trials were registered at www.chictr.org.cn as ChiCTR2100052677 and ChiCTR1900028692.

Prevalence of non-Hodgkin lymphoma patients at high-risk of failure after CAR T-cell therapy eligible for bridging radiation therapy.

Background and purpose: The aim of this study was to determine the prevalence of patients with relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) meeting high-risk criteria for early relapse after CD19 CAR T-cell therapy (CART) who have disease encompassable in a standard radiation therapy (RT) plan (defined as <5 malignant lesions) and may benefit from bridging RT prior to CD19 CART. Materials and methods: This is a single-center, retrospective study of patients with R/R NHL who received CD19 CART from 2018 to 2022. Eligible patients had pre-apheresis radiologic studies available. All patients were classified by number of lesions and history of high-risk disease criteria: bulky disease ≥10 cm, ≥1 extranodal (EN) sites, LDH ≥normal, or ≥1 lesion with SUVmax ≥10. Results: A total of 81 patients with R/R NHL were evaluated. Based on our definition, 40 (49%) patients would have been eligible for bridging RT, including 38 patients who met high-risk criteria: 31 with ≥1 EN site, 19 had ≥1 lesion with SUVmax ≥10, 16 with bulky disease, and 3 with elevated LDH. At 3 months after CART, ORRs in high-risk patients with <5 lesions, ≥5 lesions, and no lesions on pre-apheresis studies were 76% (CR 69%, PR 7%), 70% (CR 60%, PR 10%), and 80% (CR 80%), respectively. Conclusion: Approximately 47% (38/81) of patients were classified as at high risk of relapse after CART with disease encompassable in a standard radiation plan and eligible for bridging RT studies.

CAR-T cells for the treatment of pediatric chronic myeloid leukemia in repeatedly relapsed lymphoid blast phase.

Chronic myeloid leukemia presenting de novo in the blast phase (CML-BP) is a rare diagnosis among pediatric malignancies. We report on a 16-year-old male who presented with CML-BP lymphoid at diagnosis. He was treated with shortened acute lymphoblastic leukemia induction plus the tyrosine kinase inhibitor (TKI) imatinib followed by dasatinib. After achieving molecular remission (MR), hematopoietic stem cell transplantation (HSCT) was performed early after diagnosis. Despite prophylactic dasatinib, he relapsed 3 months later with the kinase domain mutation T315I. Multiple therapeutic approaches including ponatinib, blinatumomab, a 2nd HSCT from a different donor, donor lymphocyte infusions, and high-dose asciminib all resulted in subsequent relapse. Another molecular response was achieved by combining ponatinib plus asciminib with chemotherapy. In this situation, CD19-directed CAR-T cells (Kymriah®) were administered for compassionate use and tolerated without adverse events. Compared to all prior therapies, CAR T-cells maintained remission. After 12 months of follow-up, complete B-cell aplasia and low numbers of CAR-T cells are detectable in the peripheral blood, potentially mediating long-term disease control.

Non-industrial production of therapeutic lentiviral vectors: How to provide vectors to academic CAR-T.

Bringing effective cancer therapy in the form of chimeric antigen receptor technology to untapped markets faces numerous challenges, including a global shortage of therapeutic lentiviral or retroviral vectors on which all current clinical therapies using genetically modified T cells are based. Production of these lentiviral vectors in academic settings in principle opens the way to local production of therapeutic cells, which is the only economically viable approach to make this therapy available to patients in developing countries. The conditions for obtaining and concentrating lentiviral vectors have been optimized and described. The calcium phosphate precipitation method was found to be suitable for transfecting high cell-density cultures, a prerequisite for high titers. We describe protocols for gradually increasing production from 6-well plates to P100 plates, T-175 flasks, and 5-layer stacks while maintaining high titers, >108 transducing units. Concentration experiments using ultracentrifugation revealed the advantage of lower centrifugation speeds compared to competing protocols. The resulting batches of lentiviral vectors had a titer of 1010 infectious particles and were used to transduce primary human T lymphocytes generating chimeric antigen receptor T cells, the quality of which was checked and found potential applicability for treatment.

Generating universal anti-CD19 CAR T cells with a defined memory phenotype by CRISPR/Cas9 editing and safety evaluation of the transcriptome.

Introduction: Chimeric antigen receptor-expressing T cells (CAR T cells) have revolutionized cancer treatment, particularly in B cell malignancies. However, the use of autologous T cells for CAR T therapy presents several limitations, including high costs, variable efficacy, and adverse effects linked to cell phenotype. Methods: To overcome these challenges, we developed a strategy to generate universal and safe anti-CD19 CAR T cells with a defined memory phenotype. Our approach utilizes CRISPR/Cas9 technology to target and eliminate the B2M and TRAC genes, reducing graft-versus-host and host-versus-graft responses. Additionally, we selected less differentiated T cells to improve the stability and persistence of the universal CAR T cells. The safety of this method was assessed using our CRISPRroots transcriptome analysis pipeline, which ensures successful gene knockout and the absence of unintended off-target effects on gene expression or transcriptome sequence. Results: In vitro experiments demonstrated the successful generation of functional universal CAR T cells. These cells exhibited potent lytic activity against tumor cells and a reduced cytokine secretion profile. The CRISPRroots analysis confirmed effective gene knockout and no unintended off-target effects, validating it as a pioneering tool for on/off-target and transcriptome analysis in genome editing experiments. Discussion: Our findings establish a robust pipeline for manufacturing safe, universal CAR T cells with a favorable memory phenotype. This approach has the potential to address the current limitations of autologous CAR T cell therapy, offering a more stable and persistent treatment option with reduced adverse effects. The use of CRISPRroots enhances the reliability and safety of gene editing in the development of CAR T cell therapies. Conclusion: We have developed a potent and reliable method for producing universal CAR T cells with a defined memory phenotype, demonstrating both efficacy and safety in vitro. This innovative approach could significantly improve the therapeutic landscape for patients with B cell malignancies.

Preclinical evaluation of cyclophosphamide and fludarabine combined with CD19 CAR-T in the treatment of B-cell hematologic malignancies in vivo.

Background: Chimeric antigen receptor T (CAR-T) cell therapy has achieved marked therapeutic success in ameliorating hematological malignancies. However, there is an extant void in the clinical guidelines concerning the most effective chemotherapy regimen prior to chimeric antigen receptor T (CAR-T) cell therapy, as well as the optimal timing for CAR-T cell infusion post-chemotherapy. Materials and Methods: We employed cell-derived tumor xenograft (CDX) murine models to delineate the optimal pre-conditioning chemotherapy regimen and timing for CAR-T cell treatment. Furthermore, transcriptome sequencing was implemented to identify the therapeutic targets and elucidate the underlying mechanisms governing the treatment regimen. Results: Our preclinical in vivo evaluation determined that a combination of cyclophosphamide and fludarabine, followed by the infusion of CD19 CAR-T cells five days subsequent to the chemotherapy, exerts the most efficacious therapeutic effect in B-cell hematological malignancies. Concurrently, RNA-seq data indicated that the therapeutic efficacy predominantly perturbs tumor cell metabolism, primarily through the inhibition of key mitochondrial targets, such as C-Jun Kinase enzyme (C-JUN). Conclusion: In summary, the present study offers critical clinical guidance and serves as an authoritative reference for the deployment of CD19 CAR-T cell therapy in the treatment of B-cell hematological malignancies.

Consolidation with First and Second Allogeneic Transplants in Adults with Relapsed/Refractory B-ALL Following Response to CD19CAR T Cell Therapy.

CD19-targeted chimeric antigen receptor T cell (CAR-T) therapy has led to unprecedented rates of complete remission (CR) in children and adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL), yet the majority of adults relapse after initial response. One proposed method to extend the durability of remission in adults following response to CAR-T therapy is consolidation with allogeneic hematopoietic cell transplantation (alloHCT). Considering the limited published data for the utility of post CAR-T therapy consolidative alloHCT in r/r B-ALL, especially data related to patients receiving a second alloHCT, we sought to describe outcomes of patients with r/r B-ALL at our institution who received their first or second alloHCT following response to CAR-T therapy. We performed a retrospective analysis of adult patients with r/r B-ALL who responded to either investigational or standard of care (SOC) CD19-targeted CAR-T therapy and underwent consolidation with alloHCT while in CR without interim therapy. We identified 45 patients, of whom 26 (58%) and 19 (42%) received their first and second alloHCT as consolidation post CAR-T therapy, respectively. The median age was 31 years (range: 19-67) and 31 (69%) patients were Hispanic. Ph-like was the most common genetic subtype and comprised over half of cases (53%; n = 24). The median number of prior therapies pre-transplant was 5 (range: 2-7), and disease status at the time of alloHCT was CR1, CR2 or ≥CR3 in 7 (16%), 22 (49%) and 16 (35%) patients, respectively. The median time from CAR-T therapy until alloHCT was 93 (range: 42-262) days. The conditioning regimen was radiation-based myeloablative (MAC) in 22 (49%) patients. With a median follow-up of 2.47 years (range: 0.13-6.93), 2-year overall survival (OS), relapse free survival (RFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 57.3% (95% CI: 0.432-0.760), 56.2% (95% CI: 0.562-0.745), 23.3% (95% CI: 0.13-0.42), and 20.4% (95% CI: 0.109-0.384), respectively. Two-year OS (52% vs. 68%, P = .641), RFS (54% vs. 59%, P = .820), CIR (33.5% vs. 8.5%, P = .104), and NRM (12.5% vs. 32.2%, P = .120) were not significantly different between patients who underwent their first vs. second transplant, respectively. In univariate analysis, only Ph-like genotype was associated with inferior RFS (P = .03). AlloHCT post CAR-T response is associated with a relatively low early mortality rate and encouraging survival results in high-risk adults with r/r B-ALL, extending to the second alloHCT for fit and eligible patients.

Managing Infection Complications in the Setting of Chimeric Antigen Receptor T cell (CAR-T) Therapy.

Chimeric antigen receptor T-cell (CAR T-cell) therapy has changed the paradigm of management of non-Hodgkin's lymphoma (NHL) and Multiple Myeloma. Infection complications have emerged as a concern that can arise in the setting of therapy and lead to morbidity and mortality. In this review, we classified infection complications into three categories, pre-infusion phase from the time pre- lymphodepletion (LD) up to day zero, early phase from day of infusion to day 30 post-infusion, and late phase after day 30 onwards. Infections arising in the pre-infusion phase are closely related to previous chemotherapy and bridging therapy. Infections arising in the early phase are more likely related to LD chemo and the expected brief period of grade 3-4 neutropenia. Infections arising in the late phase are particularly worrisome because they are associated with adverse risk features including prolonged neutropenia, dysregulation of humoral and adaptive immunity with lymphopenia, hypogammaglobinemia, and B cell aplasia. Bacterial, respiratory and other viral infections, protozoal and fungal infections can occur during this time . We recommend enhanced supportive care including prompt recognition and treatment of neutropenia with growth factor support, surveillance testing for specific viruses in the appropriate instance, management of hypogammaglobulinemia with repletion as appropriate and extended antimicrobial prophylaxis in those at higher risk (e.g. high dose steroid use and prolonged cytopenia). Finally, we recommend re-immunizing patients post CAR-T based on CDC and transplant guidelines.

Case report: Rapid resolution of grade IV ICANS after first line intrathecal chemotherapy with methotrexate, cytarabine and dexamethasone.

Corticosteroid therapy is the mainstay of immune effector cell-associated neurotoxicity syndrome (ICANS) management, although its use has been associated with worse overall survival (OS) and progression-free survival (PFS) after chimeric antigen receptor T-cell (CAR-T cell) therapy. Many options are being investigated for prophylaxis and management. Accumulating evidence supports the use of intrathecal (IT) chemotherapy for the management of high-grade ICANS. Here, we describe a case of a patient with stage IV Primary mediastinal B-cell lymphoma (PMBCL) successfully treated with IT methotrexate, cytarabine, and dexamethasone as first-line therapy for CD19 CAR-T cell-associated grade IV ICANS. The stable and rapid resolution of ICANS to grade 0 allowed us to discontinue systemic corticosteroid use, avoiding CAR-T cells ablation and ensuring preservation of CAR-T cell function. The described patient achieved a complete radiologic and clinical response to CD19 CAR-T cell therapy and remains disease-free after 9 months. This case demonstrates a promising example of how IT chemotherapy could be used as first-line treatment for the management of high-grade ICANS.

Acute kidney injury following treatment with CD19-specific CAR T-cell therapy in children, adolescent, and young adult patients with B-cell acute lymphoblastic leukemia.

BACKGROUND: CD19-specific chimeric antigen receptor (CAR) T-cell therapy has shown promising disease responses in patients with high-risk B-cell malignancies. However, its use may be related to complications such as immune-mediated complications, infections, and end-organ dysfunction. The incidence of post-CAR T-cell therapy acute kidney injury (AKI) in the children, adolescent, and young adult (CAYA) patient population is largely unreported. METHODS: The objectives of this study were to determine the incidence of AKI in CAYA patients with high-risk B-cell malignancies treated with CD19-CAR T-cell therapy, evaluate potential risk factors for developing AKI, and determine patterns of kidney function recovery. We conducted a retrospective analysis of 34 CAYA patients treated with CD19-CAR T-cell at a single institution. RESULTS: There was a cumulative incidence of any grade AKI by day 30 post-infusion of 20% (n = 7), with four cases being severe AKI (stages 2-3) and one patient requiring kidney replacement therapy. All episodes of AKI developed within the first 14 days after receiving CAR T-cell therapy and 50% of patients with AKI recovered kidney function to baseline within 30 days post-infusion. No evaluated pre-treatment risk factors were associated with the development of subsequent AKI; there was an association between AKI and cytokine release syndrome and neurotoxicity. We conclude that the risk of developing AKI following CD19-CAR T-cell therapy is highest early post-infusion, with most cases of AKI being severe. CONCLUSIONS: Frequent monitoring to facilitate early recognition and subsequent management of kidney complications after CD19-CAR T-cell therapy may reduce the severity of AKI in the CAYA patient population.

CD19 CAR-expressing iPSC-derived NK cells effectively enhance migration and cytotoxicity into glioblastoma by targeting to the pericytes in tumor microenvironment.

In cancer immunotherapy, chimeric antigen receptors (CARs) targeting specific antigens have become a powerful tool for cell-based therapy. CAR-natural killer (NK) cells offer selective anticancer lysis with reduced off-tumor toxicity compared to CAR-T cells, which is beneficial in the heterogeneous milieu of solid tumors. In the tumor microenvironment (TME) of glioblastoma (GBM), pericytes not only support tumor growth but also contribute to immune evasion, underscoring their potential as therapeutic targets in GBM treatment. Given this context, our study aimed to target the GBM TME, with a special focus on pericytes expressing CD19, to evaluate the potential effectiveness of CD19 CAR-iNK cells against GBM. We performed CD19 CAR transduction in induced pluripotent stem cell-derived NK (iNK) cells. To determine whether CD19 CAR targets the TME pericytes in GBM, we developed GBM-blood vessel assembloids (GBVA) by fusing GBM spheroids with blood vessel organoids. When co-cultured with GBVA, CD19 CAR-iNK cells migrated towards the pericytes surrounding the GBM. Using a microfluidic chip, we demonstrated CD19 CAR-iNK cells' targeted action and cytotoxic effects in a perfusion-like environment. GBVA xenografts recapitulated the TME including human CD19-positive pericytes, thereby enabling the application of an in vivo model for validating the efficacy of CD19 CAR-iNK cells against GBM. Compared to GBM spheroids, the presence of pericytes significantly enhanced CD19 CAR-iNK cell migration towards GBM and reduced proliferation. These results underline the efficacy of CD19 CAR-iNK cells in targeting pericytes within the GBM TME, suggesting their potential therapeutic value for GBM treatment.

CD19-CAR-DNT cells (RJMty19) in patients with relapsed or refractory large B-cell lymphoma: a phase 1, first-in-human study.

Background: Current approved chimeric antigen receptor (CAR) T-cell products are autologous cell therapies that are costly and poorly accessible to patients. We aimed to evaluate the safety and antitumor activity of a novel off-the-shelf anti-CD19 CAR-engineered allogeneic double-negative T cells (RJMty19) in patients with relapsed/refractory large B-cell lymphoma. We report the results from a first-in-human, open-label, single-dose, phase 1 study of allogeneic CD19-specific CAR double-negative T (CAR-DNT) cells. Methods: Eligibility criteria included the presence of measurable lesions, at least 2 lines of prior immunochemotherapy, and an ECOG score of 0-1. We evaluated four dose levels (DL) of RJMty19 in a 3 + 3 dose-escalation scheme: 1 × 106, 3 × 106, 9 × 106 and 2 × 107 CAR-DNT cells per kilogram of body weight. All patients received lymphodepleting chemotherapy with fludarabine and cyclophosphamide. The primary endpoints were dose-limiting toxicities (DLTs), incidence of adverse events (AEs), and clinically significant laboratory abnormalities. Secondary endpoints included evaluation of standard cellular pharmacokinetic parameters, immunogenicity, objective response rates (ORR), and disease control rate (DCR) per Lugano 2014 criteria. Findings: A total of 12 patients were enrolled between 22 July 2022 and 27 July 2023. Among these patients, 66% were classified as stage IV, 75% had an IPI score of 3 or higher, representing an intermediate risk or worse. The maximum tolerated dose was not reached because no DLT was observed. Four patient experienced grade 1 or 2 cytokine release syndrome and dizziness. The most common AEs were hematologic toxicities, including neutropenia (N = 12, 100%), leukopenia (N = 12, 100%), lymphopenia (N = 10, 83%), thrombocytopenia (N = 6, 50%), febrile neutropenia (N = 3, 25%), and anemia (N = 3, 25%). Seven subjects died till the cut-off date, five of them died of disease progression and two of them died of COVID 19. In all patients (N = 12), the ORR was 25% and CRR was 8.3%. DL1 and DL2 patients benefited less from the therapy (ORR: 17%, N = 1; DCR: 33%, N = 2). However, all DL3 patients achieved disease control (N = 3, 100%), and all DL4 patients achieved objective response (N = 3, 100%). Interpretation: Our results demonstrate that CD19-CAR-DNT cells appear to be well tolerated with promising antitumor activity in LBCL patients. Further study of this product with a larger sample size is warranted. This phase 1 study is registered on clinicaltrials.gov (NCT05453669). Funding: Wyze Biotech. Co., Ltd.

CD19-Specific CAR-T Cell Treatment of 115 Children and Young Adults with Acute B Lymphoblastic Leukemia: Long-term Follow-up.

PURPOSE: Chemotherapy has been the primary treatment for patients with B-cell acute lymphoblastic leukemia (B-ALL). However, there are still patients who are not sensitive to chemotherapy, including those with refractory/relapse (R/R) disease and those experiencing minimal residual disease (MRD) re-emergence. Chimeric antigen receptor-T lymphocytes (CAR-T) therapy may provide a new treatment option for these patients. MATERIALS AND METHODS: Our institution conducted a single-arm prospective clinical trial (ChiCTR-OPN-17013507) using CAR-T-19 to treat R/R B-ALL and MRD re-emergent patients. One hundred and fifteen patients, aged 1-25 years (median age, 8 years), were enrolled, including 67 R/R and 48 MRD re-emergent CD19-positive B-ALL patients. RESULTS: All patients achieved morphologic complete remission (CR), and within 1 month after infusion, 111 out of 115 (96.5%) patients achieved MRD-negative CR. With a median follow-up time of 48.4 months, the estimated 4-year leukemia-free survival (LFS) rate and overall survival (OS) rate were 68.7%±4.5% and 70.7%±4.3%, respectively. There were no significant differences in long-term efficacy observed among patients with different disease statuses before infusion (4-year OS: MRD re-emergence vs. R/R B-ALL, 70.6%±6.6% vs. 66.5%±6.1%, p=0.755; 4-year LFS: MRD re-emergence vs. R/R B-ALL, 67.3%±7.0% vs. 63.8%±6.2%, p=0.704). R/R B-ALL patients bridging to transplantation after CAR-T treatment had a superior OS and LFS compared to those who did not. However, for MRD re-emergent patients, there was no significant difference in OS and LFS, regardless of whether they underwent hematopoietic stem cell transplantation or not. CONCLUSION: CD19 CAR-T therapy effectively and safely cures both R/R B-ALL and MRD re-emergent patients.

[Effect of signal peptide optimized by site-directed mutagenesis on the function of chimeric antigen receptor T cells].

Signal peptides (SP) are involved in regulating the secretion level and transmembrane translocation of chimeric antigen receptors (CAR), which is crucial for CAR-T cells. This study aimed to optimize the SP sequence by site-directed mutagenesis and investigate its impact on the killing function of CD19-CAR-T. Firstly, CAR vectors targeting CD19 containing wild-type SP (SP-wtY) or two mutant SP (SP-muK or SP-muR) were constructed using gene synthesis and molecular cloning techniques. The successfully constructed vector was packaged with lentivirus, and T cells were infected. The transfection efficiency of T cells was detected by flow cytometry, while the killing effect on target cells was assessed using the calcein release method. The secretion levels of cytokines interferon-γ (IFN-γ) and interferon-α (TNF-α) were measured using enzyme linked immunosorbent assay (ELISA). The results showed that successful construction of recombinant lentivirus plasmids with wild type and signal peptide mutation. After the transferring the lentivirus into T cells, the transfection efficiency of CD19-CAR carrying three signal peptides (SP-wtY, SP-muK, or SP-muR) were 33.9%, 35.5%, and 36.8%, respectively. Further killing assay showed that the tumor-killing effect of SP-muR cells was significantly higher than that of SP-muK and SP-wtY cells. When the ratio of effector to target was 10:1, the secretion levels of cytokines IFN-γ and TNF-α of CAR-T cells of the SP-muR group were significantly higher than those in SP-muK and SP-wtY groups. In summary, this study revealed that increasing the N-terminal positive charge of the signal peptide can improve the expression efficiency of CAR and promote the killing of CD19+ target cells. These findings provide a scientific basis the optimization and clinical application of CAR structure.

The Mechanisms of Altered Blood-Brain Barrier Permeability in CD19 CAR T-Cell Recipients.

Cluster of differentiation 19 (CD19) chimeric antigen receptor (CAR) T cells are a highly effective immunotherapy for relapsed and refractory B-cell malignancies, but their utility can be limited by the development of immune effector cell-associated neurotoxicity syndrome (ICANS). The recent discovery of CD19 expression on the pericytes in the blood-brain barrier (BBB) suggests an important off-target mechanism for ICANS development. In addition, the release of systemic cytokines stimulated by the engagement of CD19 with the CAR T cells can cause endothelial activation and decreased expression of tight junction molecules, further damaging the integrity of the BBB. Once within the brain microenvironment, cytokines trigger a cytokine-specific cascade of neuroinflammatory responses, which manifest clinically as a spectrum of neurological changes. Brain imaging is frequently negative or nonspecific, and treatment involves close neurologic monitoring, supportive care, interleukin antagonists, and steroids. The goal of this review is to inform readers about the normal development and microstructure of the BBB, its unique susceptibility to CD19 CAR T cells, the role of individual cytokines on specific elements of the brain's microstructural environment, and the clinical and imaging manifestations of ICANS. Our review will link cellular pathophysiology with the clinical and radiological manifestations of a complex clinical entity.

Leveraging CD19CAR T cells early in the treatment of older patients with B-ALL: are we there yet?

Older adults (≥55 years old) with B-cell acute lymphoblastic leukemia (B-ALL) have dismal outcomes with standard chemotherapy as the result of low treatment efficacy and considerable risks for treatment-related morbidity and mortality. There has been a recent success with the introduction of novel therapies, such as blinatumomab and inotuzumab, in the frontline therapeutic paradigm in older adults with B-ALL. However, these agents have their own challenges including the limited durability of remission, the need for additional concurrent chemotherapy and the prolonged course of treatment, and limited efficacy in the setting of extramedullary disease. Here, we hypothesize that the incorporation of chimeric antigen receptor (CAR) T cell therapy as a consolidation treatment in older adults with B-cell ALL in their first complete remission is the ideal setting to advance treatment outcomes by reducing treatment toxicity, enhancing remission durability, and expanding the use of this effective therapy in this age population.

Tisagenlecleucel utilisation and outcomes across refractory, first relapse and multiply relapsed B-cell acute lymphoblastic leukemia: a retrospective analysis of real-world patterns.

Background: Tisagenlecleucel was approved by the Food and Drug Administration (FDA) in 2017 for refractory B-cell acute lymphoblastic leukemia (B-ALL) and B-ALL in ≥2nd relapse. Outcomes of patients receiving commercial tisagenlecleucel upon 1st relapse have yet to be established. We aimed to report real-world tisagenlecleucel utilisation patterns and outcomes across indications, specifically including patients treated in 1st relapse, an indication omitted from formal FDA approval. Methods: We conducted a retrospective analysis of real-world tisagenlecleucel utilisation patterns across 185 children and young adults treated between August 30, 2017 and March 6, 2020 from centres participating in the Pediatric Real-World CAR Consortium (PRWCC), within the United States. We described definitions of refractory B-ALL used in the real-world setting and categorised patients by reported Chimeric Antigen Receptor (CAR) T-cell indication, including refractory, 1st relapse and ≥2nd relapse B-ALL. We analysed baseline patient characteristics and post-tisagenlecleucel outcomes across defined cohorts. Findings: Thirty-six percent (n = 67) of our cohort received tisagenlecleucel following 1st relapse. Of 66 evaluable patients, 56 (85%, 95% CI 74-92%) achieved morphologic complete response. Overall-survival (OS) and event-free survival (EFS) at 1-year were 69%, (95% CI 58-82%) and 49%, (95% CI 37-64%), respectively, with survival outcomes statistically comparable to remaining patients (OS; p = 0.14, EFS; p = 0.39). Notably, toxicity was increased in this cohort, warranting further study. Interestingly, of 30 patients treated for upfront refractory disease, 23 (77%, 95% CI 58-90%) had flow cytometry and/or next-generation sequencing (NGS) minimum residual disease (MRD)-only disease at the end of induction, not meeting the historic morphologic definition of refractory. Interpretation: Our findings suggested that tisagenlecleucel response and survival rates overlap across patients treated with upfront refractory B-ALL, B-ALL ≥2nd relapse and B-ALL in 1st relapse. We additionally highlighted that definitions of refractory B-ALL are evolving beyond morphologic measures of residual disease. Funding: St. Baldrick's/Stand Up 2 Cancer, Parker Institute for Cancer Immunotherapy, Virginia and D.K. Ludwig Fund for Cancer Research.

Infectious complications among CD19 CAR-T cell therapy recipients: A single-center experience.

BACKGROUND: CD19 chimeric antigen receptor (CAR)-T cell therapy has emerged as an effective treatment in those with refractory or relapsed lymphoma. CD19 CAR-T cell therapy can cause direct and indirect toxic adverse effects and increased risk for infection. Infectious complications and optimal antimicrobial prophylaxis strategies are an ongoing area of investigation. METHODS: A single-center retrospective cohort study was conducted to review recipients of CD19 CAR-T cell therapy between April 2018 and December 2020. Patient characteristics and clinical outcomes were extracted from the electronic health records. RESULTS: Infectious complications were identified in 18/50 (36%) recipients with 31 episodes of infection. The median time to infection was 225 days (range 0-614). Bacterial infections were most common with bloodstream infection followed by sinusitis and skin and soft tissue infection. Eight viral infections were identified, most being respiratory viral illnesses. Two fungal infections were identified: Pneumocystis jirovecii pneumonia (PJP) and disseminated fusariosis. Seventeen infections (54.8%) were classified as severe: leading to death, requiring hospitalization, need for empiric intravenous antibiotics, or significant alteration in hospital course. No characteristics were found to be statistically significant risks for infection, although a trend toward significance was seen in prior autologous stem cell transplant recipients (p = .12) and those with recurrent neutropenia (p = .14). Three patients (6%) died from infection. CONCLUSION: Infections were common after CD19 CAR-T cell therapy and occurred beyond the first year. Further multicenter studies are needed to define infectious risks and optimize antimicrobial prophylaxis recommendations in recipients of CD19 CAR-T cell therapy.

Cell-Based Models of 'Cytokine Release Syndrome' Endorse CD40L and Granulocyte-Macrophage Colony-Stimulating Factor Knockout in Chimeric Antigen Receptor T Cells as Mitigation Strategy.

While chimeric antigen receptor (CAR) T cell therapy has shown promising outcomes among patients with hematologic malignancies, it has also been associated with undesirable side-effects such as cytokine release syndrome (CRS). CRS is triggered by CAR T-cell-based activation of monocytes, which are stimulated via the CD40L-CD40R axis or via uptake of GM-CSF to secrete proinflammatory cytokines. Mouse models have been used to model CRS, but working with them is labor-intensive and they are not amenable to screening approaches. To overcome this challenge, we established two simple cell-based CRS in vitro models that entail the co-culturing of leukemic B cells with CD19-targeting CAR T cells and primary monocytes from the same donor. Upon antigen encounter, CAR T cells upregulated CD40L and released GM-CSF which in turn stimulated the monocytes to secrete IL-6. To endorse these models, we demonstrated that neutralizing antibodies or genetic disruption of the CD40L and/or CSF2 loci in CAR T cells using CRISPR-Cas technology significantly reduced IL-6 secretion by bystander monocytes without affecting the cytolytic activity of the engineered lymphocytes in vitro. Overall, our cell-based models were able to recapitulate CRS in vitro, allowing us to validate mitigation strategies based on antibodies or genome editing.