Acute Graft-Versus-Host Disease After Humanized Anti-CD19-CAR T Therapy in Relapsed B-ALL Patients After Allogeneic Hematopoietic Stem Cell Transplant

Comprehensive Review of Early and Late Toxicities in CAR T-Cell Therapy and Bispecific Antibody Treatments for Hematologic Malignancies

Chimeric antigen receptor T-cell (or CAR-T) therapy and bispecific antibodies (BsAbs) have revolutionized the treatment of hematologic malignancies, offering new options for relapsed or refractory cases. However, these therapies carry risks of early complications, such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), and delayed issues like graft-versus-host disease (GVHD), infections, and secondary cancers. Effective management requires early diagnosis using advanced biomarkers and imaging, along with prompt interventions involving immunosuppressants, corticosteroids, and cytokine inhibitors. A multidisciplinary approach is essential, integrating hematologists, oncologists, and infectious disease specialists, with emerging strategies like targeted biologics and personalized medicine showing promise in balancing efficacy with toxicity management. Ongoing research is critical to refine diagnostics and treatments, ensuring that these therapies not only extend survival but also improve patients' quality of life. This review provides critical insights for healthcare professionals to quickly recognize and treat complications of CAR-T and BsAbs therapies. By focusing on early detection through biomarkers and imaging and outlining timely therapeutic interventions, it aims to equip the multidisciplinary care team with the knowledge necessary to manage the challenges of these advanced treatments effectively, ultimately optimizing patient outcomes.

Long-Term Survival and Immune Reconstitution of Donor-Derived Chimeric Antigen Receptor T-Cell Therapy for Childhood Molecular Relapse of B-Cell Acute Lymphoblastic Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation

Measurable residual disease (MRD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an independent risk factor for relapse in patients with acute lymphoblastic leukemia (ALL). This study aimed to assess the efficacy, safety, and immune reconstitution of chimeric antigen receptor T-cell (CAR-T) therapy in patients with molecular relapse after allo-HSCT. Eleven patients with molecular relapse of B-cell-ALL who underwent CAR-T therapy after allo-HSCT were enrolled. The rate of MRD negativity after a month of CAR-T infusion was 81.8%. Patients who bridged to second-HSCT after CAR-T therapy (n = 3) showed a trend of higher 3-year leukemia-free survival and 3-year overall survival than those who did not (n = 8; 100% vs. 75.0%; 95% CI, 45.0-104.9%; p = 0.370). No treatment-related mortalities were observed. Among patients who did not bridge to second-HSCT and remained in complete remission until the last follow-up (n = 6), five of them had not recovered normal immunoglobulin concentrations with a median follow-up of 43 months. CAR-T therapy may be a safe and effective treatment strategy to improve survival after allo-HSCT; however, the problem of prolonged hypogammaglobulinemia in patients who do not bridge to second-HSCT is worth noting.

Optimisation of a primary human CAR-NK cell manufacturing pipeline

Objectives

Autologous chimeric antigen receptor (CAR) T-cell therapy of B-cell malignancies achieves long-term disease remission in a high fraction of patients and has triggered intense research into translating this successful approach into additional cancer types. However, the complex logistics involved in autologous CAR-T manufacturing, the compromised fitness of patient-derived T cells, the high rates of serious toxicities and the overall cost involved with product manufacturing and hospitalisation have driven innovation to overcome such hurdles. One alternative approach is the use of allogeneic natural killer (NK) cells as a source for CAR-NK cell therapy. However, this source has traditionally faced numerous manufacturing challenges.

Methods

To address this, we have developed an optimised expansion and transduction protocol for primary human NK cells primed for manufacturing scaling and clinical evaluation. We have performed an in-depth comparison of primary human NK cell sources as a starting material by characterising their phenotype, functionality, expansion potential and transduction efficiency at crucial timepoints of our CAR-NK manufacturing pipeline.

Results

We identified adult peripheral blood-derived NK cells to be the superior source for generating a CAR-NK cell product because of a higher maximum yield of CAR-expressing NK cells combined with potent natural, as well as CAR-mediated anti-tumor effector functions.

Conclusions

Our optimised manufacturing pipeline dramatically improves lentiviral transduction efficiency of primary human NK cells. We conclude that the exponential expansion pre- and post-transduction and high on-target cytotoxicity make peripheral blood-derived NK cells a feasible and attractive CAR-NK cell product for clinical utility.

Adoptive cellular therapy after hematopoietic stem cell transplantation

Effective cellular therapy using CD19 chimeric antigen receptor T-cells for the treatment of advanced B-cell malignancies raises the question of whether the administration of adoptive cellular therapy (ACT) posttransplant could reduce relapse and improve survival. Moreover, several early phase clinical studies have shown the potential beneficial effects of administration of tumor-associated antigen-specific T-cells and natural killer cells posttransplant for high-risk patients, aiming to decrease relapse and possibly improve survival. In this article, we present an in-depth review of ACT after transplantation, which has the potential to significantly improve the efficacy of this procedure and revolutionize this field.

CD155/PVR determines acute myeloid leukemia targeting by Delta One T cells

ABSTRACT

Relapsed or refractory acute myeloid leukemia (AML) remains a major therapeutic challenge. We have recently developed a Vδ1+ γδ T cell-based product for adoptive immunotherapy, named Delta One T (DOT) cells, and demonstrated their cytolytic capacity to eliminate AML cell lines and primary blasts in vitro and in vivo. However, the molecular mechanisms responsible for the broad DOT-cell recognition of AML cells remain poorly understood. Here, we dissected the role of natural killer (NK) cell receptor ligands in AML cell recognition by DOT cells. Screening of multiple AML cell lines highlighted a strong upregulation of the DNAM-1 ligands, CD155/pulmonary vascular resistance (PVR), CD112/nectin-2, as well as the NKp30 ligand, B7-H6, in contrast with NKG2D ligands. CRISPR-mediated ablation revealed key nonredundant and synergistic contributions of PVR and B7-H6 but not nectin-2 to DOT-cell targeting of AML cells. We further demonstrate that PVR and B7-H6 are critical for the formation of robust immunological synapses between AML and DOT cells. Importantly, PVR but not B7-H6 expression in primary AML samples predicted their elimination by DOT cells. These data provide new mechanistic insight into tumor targeting by DOT cells and suggest that assessing PVR expression levels may be highly relevant to DOT cell-based clinical trials.

PD-1 checkpoint inhibition enhances the antilymphoma activity of CD19-CAR-iNKT cells that retain their ability to prevent alloreactivity

BACKGROUND

Relapse and graft-versus-host disease (GVHD) are the main causes of death after allogeneic hematopoietic cell transplantation (HCT). Preclinical murine models and clinical data suggest that invariant natural killer T (iNKT) cells prevent acute and chronic GVHD. In addition, iNKT cells are crucial for efficient immune responses against malignancies and contribute to reduced relapse rates after transplantation. Chimeric antigen receptors (CAR) redirect effector cells to cell surface antigens and enhance killing of target cells. With this study, we aimed to combine enhanced cytotoxicity of CD19-CAR-iNKT cells against lymphoma cells with their tolerogenic properties.

METHODS

iNKT cells were isolated from peripheral blood mononuclear cells and transduced with an anti-CD19-CAR retrovirus. After in vitro expansion, the functionality of CD19-CAR-iNKT cells was assessed by flow cytometry, image stream analysis and multiplex analysis in single-stimulation or repeated-stimulation assays. Moreover, the immunoregulatory properties of CD19-CAR-iNKT cells were analyzed in apoptosis assays and in mixed lymphocyte reactions. The effect of checkpoint inhibition through nivolumab was analyzed in these settings.

RESULTS

In this study, we could show that the cytotoxicity of CD19-CAR-iNKT cells was mediated either through engagement of their CAR or their invariant T-cell receptor, which may circumvent loss of response through antigen escape. However, encounter of CD19-CAR-iNKT cells with their target induced a phenotype of exhaustion. Consequently, checkpoint inhibition increased cytokine release, cytotoxicity and survival of CD19-CAR-iNKT cells. Additionally, they showed robust suppression of alloreactive immune responses.

CONCLUSION

In this work, we demonstrate that CAR-iNKT cells are a powerful cytotherapeutic option to prevent or treat relapse while potentially reducing the risk of GVHD after allogeneic HCT.

The 4-1BBζ costimulatory domain in chimeric antigen receptors enhances CD8+ T-cell functionality following T-cell receptor stimulation

BACKGROUND

Chimeric antigen receptor (CAR) T-cells have revolutionized the treatment of CD19- and B-cell maturation antigen-positive haematological malignancies. However, the effect of a CAR construct on the function of T-cells stimulated via their endogenous T-cell receptors (TCRs) has yet to be comprehensively investigated.

METHODS

Experiments were performed to systematically assess TCR signalling and function in CAR T-cells using anti-mesothelin human CAR T-cells as a model system. CAR T-cells expressing the CD28 or 4-1BB costimulatory endodomains were manufactured and compared to both untransduced T-cells and CAR T-cells with a non-functional endodomain. These cell products were treated with staphylococcal enterotoxin B to stimulate the TCR, and in vitro functional assays were performed by flow cytometry.

RESULTS

Increased proliferation, CD69 expression and IFNγ production were identified in CD8+ 4-1BBζ CAR T-cells compared to control untransduced CD8+ T-cells. These functional differences were associated with higher levels of phosphorylated ZAP70 after stimulation. In addition, these functional differences were associated with a differing immunophenotype, with a more than two-fold increase in central memory cells in CD8+ 4-1BBζ CAR T-cell products.

CONCLUSION

Our data indicate that the 4-1BBζ CAR enhances CD8+ TCR-mediated function. This could be beneficial if the TCR targets epitopes on malignant tissues or infectious agents, but detrimental if the TCR targets autoantigens.

CAR NK Cell Therapy for the Treatment of Metastatic Melanoma: Potential & Prospects

Melanoma is among the most lethal forms of cancer, accounting for 80% of deaths despite comprising just 5% of skin cancer cases. Treatment options remain limited due to the genetic and epigenetic mechanisms associated with melanoma heterogeneity that underlie the rapid development of secondary drug resistance. For this reason, the development of novel treatments remains paramount to the improvement of patient outcomes. Although the advent of chimeric antigen receptor-expressing T (CAR-T) cell immunotherapies has led to many clinical successes for hematological malignancies, these treatments are limited in their utility by their immune-induced side effects and a high risk of systemic toxicities. CAR natural killer (CAR-NK) cell immunotherapies are a particularly promising alternative to CAR-T cell immunotherapies, as they offer a more favorable safety profile and have the capacity for fine-tuned cytotoxic activity. In this review, the discussion of the prospects and potential of CAR-NK cell immunotherapies touches upon the clinical contexts of melanoma, the immunobiology of NK cells, the immunosuppressive barriers preventing endogenous immune cells from eliminating tumors, and the structure and design of chimeric antigen receptors, then finishes with a series of proposed design innovations that could improve the efficacy CAR-NK cell immunotherapies in future studies.

Novel Approaches to Treatment of Acute Myeloid Leukemia Relapse Post Allogeneic Stem Cell Transplantation

The management of patients with acute myeloid leukemia (AML) relapsed post allogeneic hematopoietic stem cell transplantation (HSCT) remains a clinical challenge. Intensive treatment approaches are limited by severe toxicities in the early post-transplantation period. Therefore, hypomethylating agents (HMAs) have become the standard therapeutic approach due to favorable tolerability. Moreover, HMAs serve as a backbone for additional anti-leukemic agents. Despite discordant results, the addition of donor lymphocytes infusions (DLI) generally granted improved outcomes with manageable GvHD incidence. The recent introduction of novel targeted drugs in AML gives the opportunity to add a third element to salvage regimens. Those patients harboring targetable mutations might benefit from IDH1/2 inhibitors Ivosidenib and Enasidenib as well as FLT3 inhibitors Sorafenib and Gilteritinib in combination with HMA and DLI. Conversely, patients lacking targetable mutations actually benefit from the addition of Venetoclax. A second HSCT remains a valid option, especially for fit patients and for those who achieve a complete disease response with salvage regimens. Overall, across studies, higher response rates and longer survival were observed in cases of pre-emptive intervention for molecular relapse. Future perspectives currently rely on the development of adoptive immunotherapeutic strategies mainly represented by CAR-T cells.

Safety and efficacy of immune checkpoint inhibitors after allogeneic hematopoietic cell transplantation

The immune system plays a major role in preventing infections and cancers. Impairment in immunity may facilitate the development of neoplasia owing to defective immune surveillance, among other mechanisms. Immune evasion plays a significant role in relapse after allogeneic hematopoietic cell transplantation (alloHCT); one purported mechanism is through immune checkpoint signaling pathways. Checkpoint inhibitors (CPIs) are FDA approved for relapsed classical Hodgkin's Lymphoma (cHL), primary mediastinal large B cell Lymphoma (PMBCL) and other solid tumors. Retrospective studies evaluating the outcomes of alloHCT after prior exposure to CPIs showed favorable survival outcomes but high rates of graft-versus-host disease (GVHD); the risk appears to be lower when using post-transplant cyclophosphamide as GVHD prophylaxis. CPIs have increasingly been used to prevent or treat post-alloHCT relapse. Available data, albeit limited, supports the clinical activity of CPIs in post-alloHCT relapse; however, serious and even fatal cases of GVHD have been reported. The optimal timing, schedule, dosing, and patients likely to benefit from this strategy are yet to be identified. In this review, we highlight the immune system's role in cancer surveillance and relapse prevention and discuss the current clinical evidence of CPIs use in post-alloHCT relapse.

Incidence of CD19-negative relapse after CD19-targeted immunotherapy in R/R BCP acute lymphoblastic leukemia: a review

There are inconsistencies in the reporting of CD19 antigen status following treatment with CD19-targeted therapies. A majority of evidence comes from studies reporting small sample sizes. In this review, we systematically summarize published studies that have reported rates of CD19-negative relapse after treatment with either blinatumomab or CD19-directed CAR T-cell therapy and report the rates of CD19-negative relapse when evaluated in a standardized way across trials. CD19-negative relapse appears to occur more commonly in relapses following CAR T-cell therapy compared with blinatumomab, whether proportions are calculated among all treated patients (8.7% vs 4.5%) or among patients who relapse (30% vs 22.5%). The median (range) duration of follow-up was 29.3 (17.4-50.8) and 20.4 (6.9-49.0) months for publications on blinatumomab (n = 10) and CAR T-cell therapies (n = 23), respectively. There is a need for standardized reporting of CD19 antigen status in the setting of relapse following novel immunotherapies to inform clinical practice.

Optimization of universal allogeneic CAR-T cells combining CRISPR and transposon-based technologies for treatment of acute myeloid leukemia

Despite the potential of CAR-T therapies for hematological malignancies, their efficacy in patients with relapse and refractory Acute Myeloid Leukemia has been limited. The aim of our study has been to develop and manufacture a CAR-T cell product that addresses some of the current limitations. We initially compared the phenotype of T cells from AML patients and healthy young and elderly controls. This analysis showed that T cells from AML patients displayed a predominantly effector phenotype, with increased expression of activation (CD69 and HLA-DR) and exhaustion markers (PD1 and LAG3), in contrast to the enriched memory phenotype observed in healthy donors. This differentiated and more exhausted phenotype was also observed, and corroborated by transcriptomic analyses, in CAR-T cells from AML patients engineered with an optimized CAR construct targeting CD33, resulting in a decreased in vivo antitumoral efficacy evaluated in xenograft AML models. To overcome some of these limitations we have combined CRISPR-based genome editing technologies with virus-free gene-transfer strategies using Sleeping Beauty transposons, to generate CAR-T cells depleted of HLA-I and TCR complexes (HLA-IKO/TCRKO CAR-T cells) for allogeneic approaches. Our optimized protocol allows one-step generation of edited CAR-T cells that show a similar phenotypic profile to non-edited CAR-T cells, with equivalent in vitro and in vivo antitumoral efficacy. Moreover, genomic analysis of edited CAR-T cells revealed a safe integration profile of the vector, with no preferences for specific genomic regions, with highly specific editing of the HLA-I and TCR, without significant off-target sites. Finally, the production of edited CAR-T cells at a larger scale allowed the generation and selection of enough HLA-IKO/TCRKO CAR-T cells that would be compatible with clinical applications. In summary, our results demonstrate that CAR-T cells from AML patients, although functional, present phenotypic and functional features that could compromise their antitumoral efficacy, compared to CAR-T cells from healthy donors. The combination of CRISPR technologies with transposon-based delivery strategies allows the generation of HLA-IKO/TCRKO CAR-T cells, compatible with allogeneic approaches, that would represent a promising option for AML treatment.

Analysis benefits of a second Allo-HSCT after CAR-T cell therapy in patients with relapsed/refractory B-cell acute lymphoblastic leukemia who relapsed after transplant

Background

Chimeric antigen receptor (CAR) T-cell therapy has demonstrated high initial complete remission (CR) rates in B-cell acute lymphoblastic leukemia (B-ALL) patients, including those who relapsed after transplant. However, the duration of remission requires improvements. Whether bridging to a second allogeneic hematopoietic stem cell transplant (allo-HSCT) after CAR-T therapy can improve long-term survival remains controversial. We retrospectively analyzed long-term follow-up data of B-ALL patients who relapsed post-transplant and received CAR-T therapy followed by consolidation second allo-HSCT to investigate whether such a treatment sequence could improve long-term survival.

Methods

A single-center, retrospective study was performed between October 2017 and March 2022, involving 95 patients who received a consolidation second transplant after achieving CR from CAR-T therapy.

Results

The median age of patients was 22.8 years (range: 3.3-52.8) at the second transplant. After the first transplant, 71 patients (74.7%) experienced bone marrow relapse, 16 patients (16.8%) had extramedullary relapse, 5 patients (5.3%) had both bone marrow and extramedullary relapse and 3/95 patients (3.2%) had positive minimal residual disease (MRD) only. Patients received autologous (n=57, 60.0%) or allogeneic (n=28, 29.5%) CAR-T cells, while 10 patients (10.5%) were unknown. All patients achieved CR after CAR-T therapy. Before second HSCT, 86 patients (90.5%) were MRD-negative, and 9 (9.5%) were MRD-positive. All second transplant donors were different from the first transplant donors. The median follow-up time was 623 days (range: 33-1901) after the second HSCT. The 3-year overall survival (OS) and leukemia-free survival (LFS) were 55.3% (95%CI, 44.3-66.1%) and 49.8% (95%CI, 38.7-60.9%), respectively. The 3-year relapse incidence (RI) and non-relapse mortality (NRM) were 10.5% (95%CI, 5.6-19.6%) and 43.6% (95%CI, 33.9-56.2%), respectively. In multivariate analysis, the interval from CAR-T to second HSCT ≤90 days was associated with superior LFS(HR, 4.10, 95%CI,1.64-10.24; p=0.003) and OS(HR, 2.67, 95%CI, 1.24-5.74, p=0.012), as well as reduced NRM (HR, 2.45, 95%CI, 1.14-5.24, p=0.021).

Conclusions

Our study indicated that CAR-T therapy followed by consolidation second transplant could significantly improve long-term survival in B-ALL patients who relapsed post-transplant. The second transplant should be considered in suitable patients and is recommended to be performed within 90 days after CAR-T treatment.

How I treat cytopenias after CAR T-cell therapy

Increasing use of chimeric antigen receptor T-cell therapy (CAR-T) has unveiled diverse toxicities warranting specific recognition and management. Cytopenias occurring after CAR-T infusion invariably manifest early (<30 days), commonly are prolonged (30-90 days), and sometimes persist or occur late (>90 days). Variable etiologies of these cytopenias, some of which remain incompletely understood, create clinical conundrums and uncertainties about optimal management strategies. These cytopenias may cause additional sequelae, decreased quality of life, and increased resource use. Early cytopenias are typically attributed to lymphodepletion chemotherapy, however, infections and hyperinflammatory response such as immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome may occur. Early and prolonged cytopenias often correlate with severity of cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome. Bone marrow biopsy in patients with prolonged or late cytopenias is important to evaluate for primary disease and secondary marrow neoplasm in both pediatric and adult patients. Commonly, cytopenias resolve over time and evidence for effective interventions is often anecdotal. Treatment strategies, which are limited and require tailoring based upon likely underlying etiology, include growth factors, thrombopoietin-receptor agonist, stem cell boost, transfusion support, and abrogation of infection risk. Here we provide our approach, including workup and management strategies, for cytopenias after CAR-T.

Difference in Efficacy and Safety of Anti-CD19 Chimeric Antigen Receptor T-Cell Therapy Containing 4-1BB and CD28 Co-Stimulatory Domains for B-Cell Acute Lymphoblastic Leukemia

This study quantified the differences in the efficacy and safety of different stimulation domains of anti-CD19 chimeric antigen receptor (CAR) T therapy for B-cell acute lymphoblastic leukemia (B-ALL). Clinical trials related to anti-CD19 CAR T-cell therapy for B-ALL were searched in public databases from database inception to 13 November 2021. The differences in overall survival (OS) and progression-free survival (PFS) of B-ALL patients treated with anti-CAR T-cell therapy containing 4-1BB and CD28 co-stimulatory domains were compared by establishing a parametric survival function. The overall remission rate (ORR), the proportion of people with minimal residual disease (MRD)-negative complete remission (CR), the incidence of cytokine release syndrome (CRS), and the neurotoxicity across different co-stimulatory domains was assessed using a random-effects model. The correlation between the ORR, MRD-negative CR, PFS, and OS was tested. The results showed that the median OS of anti-CAR T-cell treatment containing 4-1BB and CD28 co-stimulatory domains was 15.0 months (95% CI: 11.0-20.0) and 8.5 months (95% CI: 5.0-14.0), and the median PFS was 7.0 months (95% CI: 4.0-11.5) and 3.0 months (95% CI: 1.5-7.0), respectively. Anti-CD19 CAR T-cells in the 4-1BB co-stimulatory domain showed superior benefits in patients who achieved ORR. The incidence of neurotoxicity was significantly higher in the CD28 co-stimulatory domain of anti-CD19 CAR T-cells than in the 4-1BB co-stimulatory domain. In addition, the ORR and MRD-negative CR were strongly correlated with OS and PFS, and PFS and OS were strongly correlated. The 4-1BB co-stimulatory domain suggested a better benefit-risk ratio than the CD28 co-stimulatory domain in B-ALL.

Safety and efficacy of autologous and allogeneic humanized CD19-targeted CAR-T cell therapy for patients with relapsed/refractory B-ALL

BACKGROUND

Murine chimeric antigen receptor T (CAR-T) cell therapy has demonstrated clinical benefit in patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). However, the potential immunogenicity of the murine single-chain variable fragment domain may limit the persistence of CAR-T cell, leading to relapse.

METHODS

We performed a clinical trial to determine the safety and efficacy of autologous and allogeneic humanized CD19-targeted CAR-T cell (hCART19) for R/R B-ALL. Fifty-eight patients (aged 13-74 years) were enrolled and treated between February 2020 and March 2022. The endpoints were complete remission (CR) rate, overall survival (OS), event-free survival (EFS), and safety.

RESULTS

Overall, 93.1% (54/58) of patients achieved CR or CR with incomplete count recovery (CRi) by day 28, with 53 patients having minimal residual disease negativity. With a median follow-up of 13.5 months, the estimated 1-year OS and EFS were 73.6% (95% CI 62.1% to 87.4%) and 46.0% (95% CI 33.7% to 62.8%), with a median OS and EFS of 21.5 months and 9.5 months, respectively. No significant increase in human antimouse antibodies was observed following infusion (p=0.78). Duration of B-cell aplasia in the blood was observed for as long as 616 days, which was longer than that in our prior mCART19 trial. All toxicities were reversible, including severe cytokine release syndrome, which developed in 36% (21/58) of patients and severe neurotoxicity, which developed in 5% (3/58) of patients. Compared with our prior mCART19 trial, patients treated with hCART19 had longer EFS without increased toxicity. Additionally, our data also suggest that patients treated with consolidation therapy, including allogeneic hematopoietic stem cell transplantation or CD22-targeted CAR-T cell, following hCART19 therapy had a longer EFS than those without consolidation therapy.

CONCLUSION

hCART19 has good short-term efficacy and manageable toxicity in R/R B-ALL patients.

TRIAL REGISTRATION NUMBER

NCT04532268.

Donor Hematopoietic Stem Cell/Lymphocyte Maintenance Treatment After CAR T-Cell Therapy in Patients With B-Cell Acute Lymphoblastic Leukemia Relapse Following Stem Cell Transplant

Maintaining the efficacy of anti-CD19 chimeric antigen receptor modified (CAR) T-cell therapy in patients with B-cell acute lymphoblastic leukemia (B-ALL) relapse after allogeneic hematopoietic stem cell transplant (allo-HSCT) is an urgent problem. In this study, we aimed to compare the efficacy of donor hematopoietic stem cell infusion (DSI) therapy and donor lymphocyte infusion (DLI) therapy as a maintenance therapy after R/R B-ALL patients achieved CR in anti-CD19-CAR T-cell therapy but relapsed after allo-HSCT. In total, 22 B-ALL patients who relapsed after allo-HSCT received anti-CD19-CAR T-cell therapy. Patients who responded to CAR T-cell therapy received DSI or DLI as maintenance therapy. We compared the clinical responses, acute graft versus host disease (aGVHD), expansion of CAR-T-cells, and adverse events between the two groups. In our study, 19 patients received DSI/DLI as maintenance therapy. After DSI/DLI therapy, progression-free survival and overall survival were higher in the DSI group than in the DLI group at 365 days. The grades I and II of aGVHD was observed in four patients (36.4%) in the DSI group. Only one patient developed grade II aGVHD in the DLI group. The peaks of CAR T-cells in the DSI group were higher than those in the DLI group. IL-6 and TNF-α levels increased again in nine of 11 patients after DSI but not in the DLI group. Our findings indicate that for B-ALL patients who relapse after allo-HSCT, DSI is a feasible maintenance therapy if CR is obtained with CAR-T-cell therapy.

Serious adverse events and coping strategies of CAR-T cells in the treatment of malignant tumors

Chimeric antigen receptor T (CAR-T) cells technology has been successfully used in the treatment of B cell-derived hematological tumors and multiple myeloma. CAR-T cells are also being studied in a variety of solid tumors. Current clinical reports on CAR-T cells in the treatment of malignant tumors are abundant. The tumor-killing activity of CAR-T cells and the unique adverse effects of CAR-T cells have been confirmed by many studies. There is evidence that serious adverse events can be life-threatening. CAR-T cells therapy is increasingly used in clinical settings, so it is important to pay attention to its serious adverse events. In this review, we summarized the serious adverse events of CAR-T cells in the treatment of malignant tumors by reading literature and searching relevant clinical studies, and discussed the management and treatment of serious adverse events in an effort to provide theoretical support for clinicians who deal with such patients.

Generation and proof-of-concept for allogeneic CD123 CAR-Delta One T (DOT) cells in acute myeloid leukemia

Background

Chimeric antigen receptor (CAR)-T cells have emerged as a breakthrough treatment for relapse/refractory hematological tumors, showing impressive complete remission rates. However, around 50% of the patients relapse before 1-year post-treatment. T-cell ‘fitness’ is critical to prolong CAR-T persistence and activity. Allogeneic T cells from healthy donors are less dysfunctional or exhausted than autologous patient-derived T cells; in this context, Delta One T cells (DOTs), a recently described cellular product based on MHC/HLA-independent Vδ1⁺γδ T cells, represent a promising allogeneic platform.

Methods

Here we generated and preclinically validated, for the first time, 4-1BB-based CAR-DOTs directed against the interleukin-3α chain receptor (CD123), a target antigen widely expressed on acute myeloid leukemia (AML) blasts.

Results

CD123CAR-DOTs showed vigorous, superior to control DOTs, cytotoxicity against AML cell lines and primary samples both in vitro and in vivo, even on tumor rechallenge.

Conclusions

Our results provide the proof-of-concept for a DOT-based next-generation allogeneic CAR-T therapy for AML.

Efficacy and safety of CD19 CAR-T cell therapy for acute lymphoblastic leukemia patients relapsed after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective therapy for B-cell acute lymphoblastic leukemia (B-ALL). Although allo-HSCT can be curative for some B-ALL patients, relapse still occurs in some patients following allo-HSCT. Conventional chemotherapies show poor efficacy in B-ALL patients who have relapsed following allo-HSCT. In the past decade, chimeric antigen receptor T-cell (CAR-T) therapy has shown to be efficacious for B-ALL patients. In particular, autologous CD19 CAR-T therapy results in a high remission rate. However, there are challenges in the use of CD19 CAR-T therapy for B-ALL patients who have relapsed following allo-HSCT, including the selection of CAR-T cell source for manufacturing, post-CAR-T graft-versus-host disease (GVHD) risk, maintenance of long-term efficacy after remission through CAR-T therapy, and whether a consolidative second transplant is needed. In this review, we describe the current status of CAR-T therapy for B-ALL patients who have relapsed following allo-HSCT, the advantages and disadvantages of various CAR-T cell sources, the characteristics and management of GVHD following CAR-T therapy, and the risk factors that may affect long-term efficacy.

Understanding Tricky Cellular and Molecular Interactions in Pancreatic Tumor Microenvironment: New Food for Thought

Pancreatic ductal adenocarcinoma (PDAC) represents 90% of all pancreatic cancer cases and shows a high mortality rate among all solid tumors. PDAC is often associated with poor prognosis, due to the late diagnosis that leads to metastasis development, and limited efficacy of available treatments. The tumor microenvironment (TME) represents a reliable source of novel targets for therapy, and even if many of the biological interactions among stromal, immune, and cancer cells that populate the TME have been studied, much more needs to be clarified. The great limitation in the efficacy of current standard chemoterapy is due to both the dense fibrotic inaccessible TME barrier surrounding cancer cells and the immunological evolution from a tumor-suppressor to an immunosuppressive environment. Nevertheless, combinatorial therapies may prove more effective at overcoming resistance mechanisms and achieving tumor cell killing. To achieve this result, a deeper understanding of the pathological mechanisms driving tumor progression and immune escape is required in order to design rationale-based therapeutic strategies. This review aims to summarize the present knowledge about cellular interactions in the TME, with much attention on immunosuppressive functioning and a specific focus on extracellular matrix (ECM) contribution.

Engineering-Induced Pluripotent Stem Cells for Cancer Immunotherapy

Simple Summary

Induced pluripotent stem cells (iPSCs) that can be genetically engineered and differentiated into different types of immune cells, providing an unlimited resource for developing off-the-shelf cell therapies. Here, we present a comprehensive review that describes the current stages of iPSC-based cell therapies, including iPSC-derived T, nature killer (NK), invariant natural killer T (iNKT), gamma delta T (γδ T), mucosal-associated invariant T (MAIT) cells, and macrophages (Mφs).

Abstract

Cell-based immunotherapy, such as chimeric antigen receptor (CAR) T cell therapy, has revolutionized the treatment of hematological malignancies, especially in patients who are refractory to other therapies. However, there are critical obstacles that hinder the widespread clinical applications of current autologous therapies, such as high cost, challenging large-scale manufacturing, and inaccessibility to the therapy for lymphopenia patients. Therefore, it is in great demand to generate the universal off-the-shelf cell products with significant scalability. Human induced pluripotent stem cells (iPSCs) provide an “unlimited supply” for cell therapy because of their unique self-renewal properties and the capacity to be genetically engineered. iPSCs can be differentiated into different immune cells, such as T cells, natural killer (NK) cells, invariant natural killer T (iNKT) cells, gamma delta T (γδ T), mucosal-associated invariant T (MAIT) cells, and macrophages (Mφs). In this review, we describe iPSC-based allogeneic cell therapy, the different culture methods of generating iPSC-derived immune cells (e.g., iPSC-T, iPSC-NK, iPSC-iNKT, iPSC-γδT, iPSC-MAIT and iPSC-Mφ), as well as the recent advances in iPSC-T and iPSC-NK cell therapies, particularly in combinations with CAR-engineering. We also discuss the current challenges and the future perspectives in this field towards the foreseeable applications of iPSC-based immune therapy.

Allogeneic double-negative CAR-T cells inhibit tumor growth without off-tumor toxicities

The development of autologous chimeric antigen receptor T (CAR-T) cell therapies has revolutionized cancer treatment. Nevertheless, the delivery of CAR-T cell therapy faces challenges, including high costs, lengthy production times, and manufacturing failures. To overcome this, attempts have been made to develop allogeneic CAR-T cells using donor-derived conventional CD4⁺ or CD8⁺ T cells (T_convs), but severe graft-versus-host disease (GvHD) and host immune rejection have made this challenging. CD3⁺CD4^-CD8^- double-negative T cells (DNTs) are a rare subset of mature T cells shown to fulfill the requirements of an off-the-shelf cellular therapy, including scalability, cryopreservability, donor-independent anticancer function, resistance to rejection, and no observed off-tumor toxicity including GvHD. To overcome the challenges faced with CAR-T_convs, we evaluated the feasibility, safety, and efficacy of using healthy donor-derived allogeneic DNTs as a CAR-T cell therapy platform. We successfully transduced DNTs with a second-generation anti-CD19-CAR (CAR19) without hampering their endogenous characteristics or off-the-shelf properties. CAR19-DNTs induced antigen-specific cytotoxicity against B cell acute lymphoblastic leukemia (B-ALL). In addition, CAR19-DNTs showed effective infiltration and tumor control against lung cancer genetically modified to express CD19 in xenograft models. CAR19-DNT efficacy was comparable with that of CAR19-T_convs. However, unlike CAR19-T_convs, CAR19-DNTs did not cause alloreactivity or xenogeneic GvHD-related mortality in xenograft models. These studies demonstrate the potential of using allogeneic DNTs as a platform for CAR technology to provide a safe, effective, and patient-accessible CAR-T cell treatment option.

The next wave of cellular immunotherapies in pancreatic cancer

Pancreatic cancer is an aggressive disease that is predicted to become the second leading cause of cancer-related death worldwide by 2030. The overall 5-year survival rate is around 10%. Pancreatic cancer typically presents late with locally advanced or metastatic disease, and there are limited effective treatments available. Cellular immunotherapy, such as chimeric antigen receptor (CAR) T cell therapy, has had significant success in treating hematological malignancies. However, CAR T cell therapy efficacy in pancreatic cancer has been limited. This review provides an overview of current and ongoing CAR T cell clinical studies of pancreatic cancer and the major challenges and strategies to improve CAR T cell efficacy. These strategies include arming CAR T cells; developing off-the-shelf allogeneic CAR T cells; using other immune CAR cells, like natural killer cells and tumor-infiltrating lymphocytes; and combination therapy. Careful incorporation of preclinical models will enhance management of affected individuals, assisting incorporation of cellular immunotherapies. A multifaceted, personalized approach involving cellular immunotherapy treatment is required to improve pancreatic cancer outcomes.

Natural Killer Cell-Mediated Immunotherapy for Leukemia

Simple Summary

Conventional therapies such as chemotherapy and radiation in leukemia increase infection susceptibility, adverse side effects and immune cell inactivation. Natural killer (NK) cells are the first line of defense against cancer and are critical in the recognition and cytolysis of rapidly dividing and abnormal cell populations. In this review, we describe NK cells and NK cell receptors, functional impairment of NK cells in leukemia, NK cell immunotherapies currently under investigation including monoclonal antibodies (mAbs), adoptive transfer, chimeric antigen receptor-NKs (CAR-NKs), bi-specific/tri-specific killer engagers (BiKEs/TriKEs) and potential targets of NK cell-mediated immunotherapy for leukemia in the future.

Abstract

Leukemia is a malignancy of the bone marrow and blood resulting from the abnormal differentiation of hematopoietic stem cells (HSCs). There are four main types of leukemia including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL). While chemotherapy and radiation have been conventional forms of treatment for leukemia, these therapies increase infection susceptibility, adverse side effects and immune cell inactivation. Immunotherapies are becoming promising treatment options for leukemia, with natural killer (NK) cell-mediated therapy providing a specific direction of interest. The role of NK cells is critical for cancer cell elimination as these immune cells are the first line of defense against cancer proliferation and are involved in both recognition and cytolysis of rapidly dividing and abnormal cell populations. NK cells possess various activating and inhibitory receptors, which regulate NK cell function, signaling either inhibition and continued surveillance, or activation and subsequent cytotoxic activity. In this review, we describe NK cells and NK cell receptors, functional impairment of NK cells in leukemia, NK cell immunotherapies currently under investigation, including monoclonal antibodies (mAbs), adoptive transfer, chimeric antigen receptor-NKs (CAR-NKs), bi-specific/tri-specific killer engagers (BiKEs/TriKEs) and future potential targets of NK cell-based immunotherapy for leukemia.

[Complications other than infections, CRS and ICANS following CAR T-cells therapy: Recommendations of the Francophone Society of bone marrow transplantation and cell therapy (SFGM-TC)]

CAR-T cells are an innovative treatment for an increasing number of patients, particularly since the extension of their indication to mantle lymphoma and multiple myeloma. Several complications of CAR T-cell therapy, that were first described as exceptional, have now been reported in series of patients, since its first clinical use in 2011. Among them, cardiac complications, delayed cytopenias, acute and chronic Graft versus Host Disease, and tumoral lysis syndrome are recognized as specific potent complications following CAR T-cells infusion. During the twelfth edition of practice harmonization workshops of the Francophone society of bone marrow transplantation and cellular therapy (SFGM-TC), a working group focused its work on the management of these complications with focuses the epidemiology, the physiopathology and the risk factors of these 4 side effects. Our recommendations apply to commercial CAR-T cells, in order to guide strategies for the management of complications associated with this new therapeutic approach.

Efficacy and Safety of Chimeric Antigen Receptor T Cells in Acute Lymphoblastic Leukemia With Post-Transplant Relapse

Twenty patients with relapsed B-ALL after HSCT were treated with CAR T cell therapy and were evaluated for efficacy and safety. Twelve patients previously received haploidentical transplantation, while 8 patients received HLA-matched transplantation. The median relapse time was 12 months (range, 4 to 72). Thirteen patients received autologous CAR T cells, and 7 patients received allogeneic CAR T cells, which were derived from transplant donors. The median infusion dose was 2.9×106/kg (range, 0.33 to 12×106/kg). Nineteen patients were evaluated for efficacy, among which 17 patients (89.5%) achieved MRD negative. The CR rates in the HLA-matched transplantation group and haploidentical transplantation group were 100% (7/7) and 83.3% (10/12), respectively. The median follow-up time was 9.80 months (range, 2.40 to 64.97). Ten patients (50%) died of relapse, 3 patients (15%) died of infection, and 1 patient (5%) died of aGVHD. Fifteen patients (75%) developed CRS, including 3 (20%) grade 1 CRS, 6 (40%) grade 2 CRS, and 6 (40%) grade 3 CRS. Ten patients (50%) developed aGVHD, including 1 (10%) grade I aGVHD, 6 (60%) grade II aGVHD, and 3 (30%) grade III aGVHD. The log rank test showed that CAR T cell origin was correlated with aGVHD occurrence in the haploidentical transplantation group (P = 0.005). The authors’ study indicated that the initial efficacy and safety of CAR T cell therapy for patients with post-transplant relapse were satisfactory. However, aGVHD was a concern in patients with a history of haploidentical transplantation occupied with allogeneic CAR T cells, which warrants clinical attention.

The immunologic aspects of cytokine release syndrome and graft versus host disease following CAR T cell therapy

Chimeric antigen receptor (CAR) T cells are the pioneers of cancer immunotherapy, which to this date have several FDA-approved products. They have been substantially improved since their first introduction in 1993 and have shown promising results regardless of their inevitable side effects. Cytokine release syndrome (CRS), the most common toxicity after CAR T cell treatment, is affiliated to a systemic inflammation through surge of cytokines, mainly IL-6, IL-1, and INF-γ. Furthermore, difference between histocompatibility antigens activates the graft versus host disease (GvHD) effect of the allogenic CAR T cells against the host cells. Immunological reactions induced by CAR T cells in the form of CRS or GvHD is necessary for fostering good responses, while excess reactions can potentially threaten patient life. In this review, we first describe the history, applications, and structure of CAR T cells, followed by a comprehensive review of CRS regarding its definition, management, and immunological aspects. Finally, we discuss about the clinical aspects of CRS and GvHD after CAR T cell therapy and how to harness anti-tumoral effects, while mitigating the adverse effects.

Intensive Debulking Chemotherapy Improves the Short-Term and Long-Term Efficacy of Anti-CD19-CAR-T in Refractory/Relapsed DLBCL With High Tumor Bulk

Anti-CD19 chimeric antigen receptor T (CAR-T) therapy has achieved remarkable effects in refractory/relapsed (R/R) diffuse large B-cell lymphoma (DLBCL). However, when high tumor bulk occurs, patients tend to early progression after CAR-T therapy. Here, we investigated whether pretreatment with intensive debulking chemotherapy could improve the outcome of CAR-T in such patients. Fifty-seven patients with R/R DLBCL were enrolled, and 42 patients received anti-CD19-CAR-T therapy, among which, 25 patients (the combined group) with high tumor bulk received debulking chemotherapy and anti-CD19-CAR-T therapy sequentially. Another 17 patients (the control group) without high tumor bulk received anti-CD19-CAR-T therapy only. According to the response to debulking chemotherapy, patients of the combined group were divided into chemo-sensitive and chemo-refractory groups. Within 2 months, the objective response rate (ORR) was higher in the chemo-sensitive group than in the chemo-refractory group (P = 0.031). Grades 1-3 cytokine release syndrome (CRS) was reported, and no difference was shown in CRS grade distribution between the chemo-sensitive and chemo-refractory groups (P = 0.514). The chemo-sensitive group demonstrated longer overall survival (OS) than the chemo-refractory group (P = 0.042). Of the chemo-sensitive group, the 1-year disease free survival (DFS) and OS rates were 52.6 and 57.9%, respectively. Besides, no significant differences were found in ORR, DFS, and OS between the chemo-sensitive and control groups (ORR: P = 0.593; DFS: P = 0.762; OS: P = 0.531). In summary, effective debulking chemotherapy improved the short-term ORR and long-term OS of CAR-T therapy in R/R DLBCL with high tumor bulk, with outcomes comparable to those of R/R DLBCL without high tumor bulk. The clinical trial of our study was registered at http://www.chictr.org.cn/index.aspx as ChiCTR-ONN-16009862 and ChiCTR1800019622.

Clinical Trial Registration

http://www.chictr.org.cn/index.aspx, identifier (ChiCTR-ONN-16009862 and ChiCTR1800019622).

Graft-versus-host disease risk after chimeric antigen receptor T-cell therapy: the diametric opposition of T cells

Chimeric antigen receptor (CAR) T-cell therapy has brought a paradigm shift in the management of haematological malignancies and has opened novel avenues of investigational therapeutic strategies. Given these encouraging responses, it has become imperative to understand the full spectrum of biology and potential toxicities that can arise from these novel agents, as well as those under investigation. With the increasing use of CAR T-cell therapy for relapse following allogeneic haematopoietic cell transplantation (HCT) and the imminence of allogeneic CAR T cells, risks from T cell-based therapy, such as the previously well-recognised graft-versus-host disease (GVHD), have gained prominence and warrant explanation. In the present review, we discuss the risk of GVHD in the: (1) post-HCT setting using recipient or donor-derived CAR T cells, as well as (2) non-HCT setting using autologous, as well as allogeneic T-cell therapies. A better understanding of this risk is important to advance the field and ensure safe development and use of these agents in the clinic.

[Allogeneic donor-derived CD19 CAR-T therapy of relapsed B-cell acute lmphoblastic leukemia after allogeneic hematopoietic stem cell transplantation]

Objective: To investigate the long term efficacy and side effects of a donor-derived CD19 chimeric antigen receptor (CAR) T-cell (HI19α-4-1BB-ζ CAR-T) therapy in the treatment of patients with relapsed B-cell acute lymphoblastic leukemia (B-ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) . Methods: A total of 9 subjects with relapsed B-ALL post allo-HSCT received donor-derived CD19 CAR-T therapy from July 2017 to May 2020. All subjects were infused with donor CD3-positive T cells after lymphodepletion chemotherapy, and a median dose of CAR-T cells was 1.79 (range, 0.86-3.53) ×10(6)/kg. Results: ①All subjects achieved complete remission and MRD-negative at 28-42 d post CAR-T cells infusion. ②Cytokine releasing syndrome (CRS) occurrd in all subjects and was grade 3 in 2, grade 2 in 4, grade 1 in 3 cases respectively. Four subjects developed immune effector cell-associated neurotoxicity syndrome (ICANS) , which was grade 2 in 1, grade 1 in 3. One subject developed grade IV acute graft-versus-host disease (GVHD) , and side effects were all controllable. ③Four subjects relapsed at a median period of 8.6 (4.6-19.3) months, 2 subjects died of disease progression after receiving chemotherapy and another one also died of disease progression 14 months after a second transplant, only 1 subject achieved complete remission after CD22 CAR-T cell therapy. Until last follow-up date, 6 subjects were leukemia-free and achieved complete donor chimerism. The estimated 1-year and 2-year leukemia-free survival (LFS) rate was 63.5% and 50.8%, with a median LFS of 18.1 months. ④After a median follow-up of 25.1 (range, 6.9-36.7) months, the estimated 2-year and 2.5-year OS rate were 87.5% and 52.5%, respectively. Conclusion: The donor-derived CD19 CAR-T cell therapy obtain a high remission rate in relapsed B-ALL patients post allo-HSCT with tolerable side effects, half subjects survived more than 2 years without disease recurrence, though long-term efficacy requires further observation. Chinese Clinical Trial Registry: ChiCTR1900025419.

Ibrutinib improves the efficacy of anti-CD19-CAR T-cell therapy in patients with refractory non-Hodgkin lymphoma

The efficacy and side effects of the second‐time humanized CD19 chimeric antigen receptor (CD19‐CAR) T‐cell therapy after unsuccessful first‐time anti‐CD19‐CAR T‐cell therapy and subsequent ibrutinib salvage treatment were observed in patients with refractory B‐cell lymphoma. In our study, 3 patients with refractory mantle cell lymphoma (MCL) and 4 patients with refractory follicular lymphoma (FL) reached stable disease (SD), partial remission (PR), or progression of disease (PD) after first‐time humanized anti‐CD19‐CAR T‐cell therapy. They received ibrutinib as a salvage treatment and kept an SD in the following 7‐16 mo, but their disease progressed again during ibrutinib salvage treatment. All 7 patients received a second‐time humanized anti‐CD19‐CAR T‐cell therapy, which was the same as their first‐time anti‐CD19‐CAR T‐cell therapy. In total, 3 MCL patients and 3 FL patients reached complete response (CR) with the second‐time anti‐CD19‐CAR T‐cell therapy combined with ibrutinib, whereas 1 FL patient reached PR. There were no differences in the transduction efficiency and proliferation between the 2 instances of anti‐CD19‐CAR T‐cell therapy. However, the second‐time anti‐CD19‐CAR T‐cell therapy led to higher peaks of anti‐CD19‐CAR T cells and anti‐CD19‐CAR gene copies, but also to higher grades of cytokine release syndrome (CRS) and more serious hematological toxicity. The successful outcome of the second‐time anti‐CD19‐CAR T‐cell therapy might suggest that the previous ibrutinib treatment improved the activities of anti‐CD19‐CAR T cells.