Early and late hematologic toxicity following CD19 CAR-T cells

Mitigation and Management of Common Toxicities Associated with the Administration of CAR-T Therapies in Oncology Patients

Chimeric antigen receptor T-cell (CAR-T) therapies are one of the main approaches among targeted cellular therapies. Despite the potential benefit and durable responses observed in some patients receiving CAR-T therapies, serious and potentially fatal toxicities remain a major challenge. The most common CAR-T-associated toxicities include cytokine release syndrome (CRS), neurotoxicity, cytopenias, and infections. While CRS and neurotoxicity are generally managed with tocilizumab and corticosteroids, respectively, high-grade toxicities can be life-threatening. Close postinfusion monitoring and assessment of clinical laboratory parameters, patient-related and clinical risk factors (e.g., age, tumor burden, comorbidities, baseline laboratory parameters, and underlying abnormalities), and therapy-related risk factors (e.g., CAR-T type, dose, and CAR-T-induced toxicity) are effective strategies to mitigate the toxicities. Clinical laboratory parameters, including various cytokines, have been identified for CRS (interleukin [IL]-1, IL-2, IL-5, IL-6, IL-8, IL-10, C-reactive protein [CRP], interferon [IFN]-γ, ferritin, granulocyte-macrophage colony-stimulating factor [GM-CSF], and monocyte chemoattractant protein-1), neurotoxicity (IL-1, IL-2, IL-6, IL-15, tumor necrosis factor [TNF]-α, GM-CSF, and IFN-γ), cytopenias (IL-2, IL-4, IL-6, IL-10, IFN-γ, ferritin, and CRP), and infections (IL-8, IL-1β, CRP, IFN-γ, and procalcitonin). CAR-T-associated toxicities can be monitored and treated to mitigate the risk to patients. Assessment of alterations in clinical laboratory parameter values that are correlated with CAR-T-associated toxicities may predict development and/or severity of a given toxicity, which can improve patient management strategies and ultimately enable the patients to better tolerate these therapies.

The role of single cell transcriptomics for efficacy and toxicity profiling of chimeric antigen receptor (CAR) T cell therapies

CAR T cells are genetically modified T cells that target specific epitopes. CAR T cell therapy has proven effective in difficult-to-treat B cell cancers and is now expanding into hematology and solid tumors. To date, approved CAR therapies target only two specific epitopes on cancer cells. Identifying more suitable targets is challenged by the lack of truly cancer-specific structures and the potential for on-target off-tumor toxicity. We analyzed gene expression of potential targets in single-cell data from cancer and healthy tissues. Because safety and efficacy can ultimately only be defined clinically, we selected approved and investigational targets for which clinical trail data are available. We generated atlases using >300,000 cells from 48 patients with follicular lymphoma, multiple myeloma, and B-cell acute lymphoblastic leukemia, and integrated over 3 million cells from 35 healthy tissues, harmonizing datasets from over 300 donors. To contextualize findings, we compared target expression patterns with outcome data from clinical trials, linking target profiles to efficacy and toxicity, and ranked 15 investigational targets based on their similarity to approved ones. Target expression did not significantly correlate with reported clinical toxicities in patients undergoing therapy. This may be attributed to the intricate interplay of patient-specific variables, the limited amount of metadata, and the complexity underlying toxicity. Nevertheless, our study serves as a resource for retrospective and prospective target evaluation to improve the safety and efficacy of CAR therapies.

CD19 CAR-T With Axicabtagene Ciloleucel in R/R Large B-Cell Lymphoma With/Without Prior Autologous Stem Cell Transplant

BACKGROUND

Anti-CD19 CAR-T therapy has been a breakthrough in treatment of primary refractory or relapsed large B-cell lymphoma (r/r LBCL) and is poised to supplant previous second line of high dose chemotherapy and autologous stem cell transplantation (HDT/ASCT). However, in clinical practice, high risk patients with chemoimmunotherapy sensitive disease continue to receive salvage chemoimmunotherapy or cannot access CAR-T in a timely manner and thus may still proceed to HDT/ASCT. Little is known about clinical outcomes of CAR-T in patients who receive HDT/ASCT compared to those who are transplant-naïve.

DESIGN

We conducted a retrospective study of patients with r/r LBCL who previously underwent HDT/ASCT or were transplant-naïve (n = 97) and received axicabtagene ciloleucel after at least 2 prior therapy lines between 1/1/2018 to 12/31/2021. Primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS), nonrelapse mortality (NRM), and cumulative incidence of relapse/progression.

RESULTS

82 (84.5%) patients were transplant-naïve and 15 (15.5%) previously received HDT/ASCT. No differences were found in the incidence of high-grade cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome, length of hospital admission, or incidence of cytopenia at day 30. 90-day response, PFS, OS, cumulative incidence of relapse/progression, and NRM were not different. Factors that adversely affected outcomes were prior bridging therapy, elevated LDH or thrombocytopenia at time of lymphodepleting chemotherapy, and worse ECOG performance status.

CONCLUSION

Prior treatment with HDT/ASCT does not compromise the safety and efficacy of anti-CD19 CAR-T therapy, suggesting a continued role for HDT/ASCT in treatment of select patients with r/r DLBCL.

Beyond maximum grade: tolerability of immunotherapies, cellular therapies, and targeted agents in haematological malignancies

The increasing use of immunotherapeutic approaches, cellular therapies, and targeted agents is rapidly and profoundly changing the treatment paradigms of haematological malignancies. These novel therapies are increasingly incorporated into earlier lines of treatment. Some are administered for a fixed duration, often with curative intent, whereas others are administered chronically for disease control. The associated acute, mid-term, and long-term toxic effects can differ markedly from conventional cytotoxic chemotherapy and radiotherapy. Accumulating clinical experience and data enable identification of class-specific effects and development of consensus-based guidelines for toxicity management. In this third paper in the Series on adverse event reporting, we build on our emerging understanding of toxicity profiles of novel treatments to propose an actionable framework for improved assessment, reporting, and critical appraisal of treatment tolerability. We discuss recent insights regarding second cancers and the relevance of infectious complications, explore tolerability aspects of time-limited treatments, and suggest approaches to address gaps in tolerability assessment.

Sensitizing solid tumors to CAR-mediated cytotoxicity by lipid nanoparticle delivery of synthetic antigens

Chimeric antigen receptor (CAR) T cell immunotherapy relies on CAR targeting of tumor-associated antigens; however, heterogenous antigen expression, interpatient variation and off-tumor expression by healthy cells remain barriers. Here we develop synthetic antigens to sensitize solid tumors for recognition and elimination by CAR T cells. Unlike tumor-associated antigens, we design synthetic antigens that are orthogonal to endogenous proteins to eliminate off-tumor targeting and that have a small genetic footprint to facilitate efficient tumor delivery to tumors by lipid nanoparticles. Using a camelid single-domain antibody (VHH) as a synthetic antigen, we show that adoptive transfer of anti-VHH CAR T cells to female mice bearing VHH-expressing tumors reduced tumor burden in multiple syngeneic and xenograft models of cancer, improved survival, induced epitope spread, protected against tumor rechallenge and mitigated antigen escape in heterogenous tumors. Our work supports the in situ delivery of synthetic antigens to treat antigen-low or antigen-negative tumors with CAR T cells.

Hematologic and lymphatic disorders associated with chimeric antigen receptor T-cell therapy: a pharmacovigilance analysis of the FDA adverse event reporting system (FAERS) database

BACKGROUND

As the application of Chimeric Antigen Receptor T-cell (CAR-T) therapy in cancer treatment becomes increasingly widespread, associated hematologic and lymphatic system adverse events pose significant challenges to its clinical use. Therefore, we aim to comprehensively investigate and summarize the hematologic and lymphatic system AEs associated with CAR-T therapy.

METHODS

We extracted CAR-T-related adverse event reports from the FDA Adverse Event Reporting System (FAERS) database for the period from August 2017 to December 2023. Disproportionality analysis using the Reporting Odds Ratio (ROR) and Information Component (IC) was performed to identify CAR-T-associated hematologic and lymphatic system AEs. We employed LASSO regression analysis to identify hematologic and lymphatic system AEs associated with mortality.

RESULTS

In the FAERS database, we identified 1,600 individual case safety reports of hematologic and lymphatic system AEs related to CAR-T therapy. The median age of patients was 57 years (interquartile range [IQR] 32-67), with fatal outcomes in 15.3% of cases. We identified 25 significant adverse event signals associated with CAR-T therapy. B-cell aplasia (ROR025 = 1054.56, IC025 = 4.74), cytopenia (ROR025 = 17.27, IC025 = 3.81), hypofibrinogenemia (ROR025 = 100.18, IC025 = 2.46), anemia (ROR025 = 1.87, IC025 = 0.59), febrile bone marrow aplasia (ROR025 = 55.32, IC025 = 2.70), and pancytopenia (ROR025 = 7.18, IC025 = 1.42) were the most significant hematologic and lymphatic system AEs for tisa-cel, axi-cel, brexu-cel, liso-cel, ide-cel, and cilta-cel, respectively. Most hematologic and lymphatic system AEs occurred within 10 days post-CAR-T infusion. Hematologic and lymphatic system AEs were associated with a mortality rate of 15.3%. Our analysis revealed 15 hematologic and lymphatic system AEs closely associated with mortality in CAR-T-treated patients, including splenic hemorrhage, disseminated intravascular coagulation, and pancytopenia.

CONCLUSIONS

Our study found that hematologic and lymphatic system AEs were more closely associated with anti-CD19 CAR-T and CAR-T containing CD28. Splenic hemorrhage, disseminated intravascular coagulation, and pancytopenia were identified as hematologic and lymphatic system AEs that, while less frequently reported clinically, were highly associated with mortality.

Lymphodepletion chemotherapy in chimeric antigen receptor-engineered T (CAR-T) cell therapy in lymphoma

The development of chimeric antigen receptor (CAR) T-cells, engineered from peripheral T-lymphocytes of a patient with lymphoma, in order to specifically target tumor cells, has been a revolution in adoptive cell therapy (ACT). As outlined in this review, ACT was initiated by hematopoietic cell transplantation (HSCT) and re-injection of interleukin-boosted tumor-infiltrating lymphocytes (TIL). The innovative venture of genetically modifying autologous peripheral T-cells to target them to cell-surface tumoral antigens through an antibody-derived structure (i.e. independent of major histocompatibility antigen presentation, physiologically necessary for T-cell activation), and intracytoplasmic T-cell costimulatory peptides, via a novel membrane CAR, has been an outstanding breakthrough. Here, focusing on B-cell hematological malignancies and mostly non-Hodgkin lymphoma, attention is brought to the importance of providing an optimal microenvironment for such therapeutic cells to proliferate and positively develop anti-tumoral cytotoxicity. This, perhaps paradoxically, implies a pre-infusion step of deep lymphopenia and deregulation of immunosuppressive mechanisms enhanced by tumoral cells. Fludarabine and cyclophosphamide appear to be the most efficient lymphodepletive drugs in this context, dosage being of importance, as will be illustrated by a thorough literature review.

Two-component T-cell immunotherapy enables antigen pre-targeting to reduce cytokine release without forfeiting efficacy

Contemporary T-cell immunotherapies, despite impressive targeting precision, are hindered by aberrant cytokine release and restrictive targeting stoichiometry. We introduce a two-component T-cell immunotherapy targeting B-cell malignancies: Multi-Antigen T-Cell Hybridizers (MATCH). This split antibody technology differs from current therapies by separating cancer cell-targeting components from T cell-engaging components. We demonstrate that this two-component structure facilitates tunable T-cell activation. αCD19 and αCD20 MATCH, administered in two steps, are both compared to the clinical standard bispecific antibody, blinatumomab. In vitro two-dimensional dose analysis and cytokine release data indicate MATCH improves cancer clearance with reduced cytokine release. Cytolytic mechanisms of action are evaluated. αCD20 MATCH anti-cancer efficacy is assayed using a human lymphoma murine model. Decreasing T-cell engager dose 10-fold yields comparable efficacy to non-reduced doses. Ultimately, this split-antibody paradigm may enhance antigen targeting while reducing cytokine release, with such safety and efficacy advantages augmented by the future possibility of multi-antigen targeting with MATCH.

Recovery from rituximab-associated persistent hypogammaglobulinaemia in children with nephrotic syndrome

BACKGROUND

There are limited data on the long-term outcomes and risk factors for non-recovery after development of rituximab (RTX)-associated persistent hypogammaglobulinaemia among children with idiopathic nephrotic syndrome (NS).

METHODS

A nationwide Japanese survey was conducted to determine the prognosis of patients with childhood-onset idiopathic NS who developed persistent hypogammaglobulinaemia after RTX administration. Specifically, predictors of IgG level recovery and risk factors for serious infection were examined.

RESULTS

The cohort comprised 118 patients (66.1% boys; median age at initial RTX administration, 7.5 years). Among the 121 patients diagnosed with persistent hypogammaglobulinaemia, only 31 (26.3%) recovered within a median observation period of 2.8 years; approximately 70% of patients continued to exhibit persistent hypogammaglobulinaemia. Among the patients who recovered from hypogammaglobulinaemia, the median time to recovery was 14.1 months. Patients with a history of steroid-resistant NS were less likely to recover from persistent hypogammaglobulinaemia (hazard ratio 0.28; 95% confidence interval 0.09-0.87). In addition, of the 118 eligible patients, 18 (15.3%) developed serious infections requiring hospitalization, and the main risk factor for infection during hypogammaglobulinaemia was agranulocytosis (a well-known adverse effect of RTX in children).

CONCLUSIONS

A significant portion of patients with RTX-associated persistent hypogammaglobulinaemia did not exhibit recovery even after 1 year. Moreover, the data indicate that patients with a history of steroid-resistant NS have a significantly lower probability of recovering from this condition. Agranulocytosis under hypogammaglobulinaemia was significantly associated with an elevated risk of serious infections.

Donor-derived CARCIK-CD19 cells engineered with Sleeping Beauty transposon in acute lymphoblastic leukemia relapsed after allogeneic transplantation

Non-viral engineering can ease CAR-T cell production and reduce regulatory and cost requirements. We utilized Sleeping Beauty transposon to engineer donor-derived anti-CD19.CD28.OX40.CD3zeta T cells differentiated in cytokine-induced killer (CARCIK-CD19) for B-cell precursor acute lymphoblastic leukemia (BCP-ALL) patients relapsed after allogeneic hematopoietic stem cell transplantation (alloHSCT). We report the results of CARCIK-CD19 observed in 36 patients (4 children and 32 adults) treated according to the final recommended dose. Cytokine release syndrome of grade 2 or lower occurred in 15 patients, ICANS grade 2 in 1 patient, and late-onset peripheral neurotoxicity of grade 3 in 2 patients. GVHD never occurred after treatment with allogeneic CARCIK-CD19. Complete remission was achieved by 30 out of 36 patients (83.3%), with MRD negativity in 89% of responders. With a median follow-up of 2.2 years, the 1-year overall survival was 57.0%, and event-free survival was 32.0%. The median duration of response at 1 year was 38.6%. CAR-T cells expanded rapidly after infusion and remained detectable for over 2 years. Integration site analysis after infusion showed a high clonal diversity. These data demonstrated that SB-engineered CAR-T cells are safe and induce durable remission in heavily pretreated patients with BCP-ALL relapsed after alloHSCT. Trial registration: The phase 1/2 and phase II trials are registered at www.clinicaltrials.gov as NCT#03389035 and NCT#05252403.

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

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

Utility of Thrombopoietin Receptor Agonists for Prolonged Thrombocytopenia After Chimeric Antigen Receptor T-cell Therapy

Chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment landscape for various hematological malignancies. However, it is associated with a range of hematologic complications, including severe and often prolonged thrombocytopenia. Currently, there are no known effective preventative or management measures against CAR-T-induced thrombocytopenia. At the University of Chicago Medical Center, thrombopoietin receptor agonists (TPO-RAs) eltrombopag and romiplostim have been utilized intermittently, per attending preference, in patients post CAR-T treatment presenting with prolonged thrombocytopenia (platelets <50 × 103 cells/μL for at least 14 days). However, whether these treatments yield positive outcomes in this context remains uncertain. This study aims to evaluate the efficacy and safety of TPO-RAs in patients with CAR-T-induced thrombocytopenia. The primary objective is to compare the incidence of platelet recovery (defined as two consecutive platelet counts of ≥50 × 103 cells/μL) in patients who received TPO-RAs versus those who did not for CAR-T-associated prolonged thrombocytopenia between January 1, 2018, and June 30, 2023. The secondary objectives include time to platelet recovery, incidence of clinically relevant bleed, hospital length of stay, incidence of adverse effects associated with TPO-RA administration, overall survival, and financial toxicity. This is a single-center, retrospective study conducted at the University of Chicago Medical Center. Eighty-five patients with prolonged, CAR-T-induced thrombocytopenia were enrolled in the study; 12 of these patients were managed with TPO-RA therapy while the remaining 73 received supportive care. Statistical analysis was performed using STATA, incorporating the Chi-squared test for nominal data and the Wilcoxon Rank-sum test for continuous data. A P value of <.05 was used to determine statistical significance. The incidence of platelet recovery was similar between the two groups; in the supportive care group, 53 patients (73%) experienced resolution of thrombocytopenia, compared to 9 patients (75%) in the TPO-RA treated group (P = 1.0). The median time to thrombocytopenia resolution was 56 days in the TPO-RA-treated group and 41 days in those not managed with TPO-RAs (P = .14). The median time to TPO-RA initiation postinfusion was 45 days. There were no statistically significant differences in incidence of clinically relevant bleed or readmission within 1 year of CAR-T infusion between the two groups, but 25% of patients receiving TPO-RA therapy experienced associated arthralgia requiring treatment modification. Additionally, the median cost of a course of eltrombopag was estimated at $86,921.52 per patient at the reported average wholesale price. While TPO-RAs represent a theoretical therapeutic option for CAR-T patients based on their role in chemotherapy-induced thrombocytopenia, our study showed that their use did not provide significant clinical benefit compared to the supportive care approaches. Therefore, without larger, randomized, prospective trials, we are unable to recommend TPO-RA use in this setting, given the current lack of demonstrated efficacy, potential adverse effects, and concerns regarding financial impact.

A viral infection prediction model for patients with r/r B-cell malignancies after CAR-T therapy: a retrospective analysis

Background

Chimeric antigen receptor T cell (CAR-T) therapy for relapsed/refractory (r/r) B cell acute lymphoblastic leukemia (B-ALL) and B cell non-Hodgkin lymphoma (B-NHL) patients has shown promising effects, but side effects such as viral infections have been observed.

Methods

A total of 45 patients with r/r B-ALL and r/r B-NHL were included in this retrospective study. Patient demographics were recorded, with the primary endpoint being viral infection within 3 months post CAR-T treatment. Univariate and multivariate logistic regression analyses and least absolute shrinkage and selection operator (LASSO) regression analysis were used to analyze independent factors. The patients were divided into a training cohort of 28 and a validation cohort of 17 to construct a prediction model based on determined independent factors. The model's discrimination and calibration were assessed using the receiver operating characteristic curve (ROC), calibration plot, and decision curve analysis (DCA curve).

Results

The univariate and multivariate logistic regression analyses of the 43 patients showed that low baseline lymphocyte ratio was an independent risk factor and using granulocyte colony-stimulating factor (G-CSF) early was a protective factor for viral infection after CAR-T therapy in patients with B-ALL and B-NHL. Based on that, the area under the ROC curve (AUC) of the training cohort and validation cohort was 0.935 (95% CI 0.837-1.000) and 0.869 (95%CI 0.696-1.000), respectively, showing excellent predictive value.

Conclusions

We established a nomogram to predict the factors' influence on viral infection after CAR-T therapy and found that the ratio of baseline lymphocytes and using G-CSF early or lately were able to predict viral infection after CAR-T therapy in r/r B-ALL and B-NHL.

Establishing best practice in the Australian haematology setting for the use of chimeric antigen receptor T-cell therapy for relapsed and refractory lymphoma

Autologous CD19 chimeric antigen receptor T (CAR T)-cell therapies have significantly improved clinical outcomes for many patients with relapsed and refractory (R/R) lymphoma. However, the process of delivering CAR T-cell therapy is specialised and complex, in part due to specific post-infusion toxicities. Several CAR T-cell products are now available in Australia, although not all states have treatment centres. In this review, we aim to define best practice for the referral and treatment of patients with R/R B-cell lymphoma with CAR T-cell therapy in Australia. We outline the processes for referral, optimal patient selection and best practice in the management of patients receiving CAR T cells.

Influence of CAR T-cell therapy associated complications

Since the introduction of chimeric antigen receptor (CAR) T-cell therapy, it has elicited an immense response in both targeted and residual cancers. Its clinical efficacy is often accompanied by a group of side effects that may become serious because of factors such as tumor burden, the extent of lymphodepletion, and the type of co-stimulus. It is also crucial to know the common toxicities associated with CAR T-cell therapy, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), cardiotoxicity, metabolic disorders, pulmonary toxicity, macrophage activation syndrome (MAS), prolonged cytopenia, coagulation disorders, and potential off-target effects on various organs. If not well managed, these can be fatal. However, knowledge about molecular pathways, calcineurin inhibitors, IL-6 receptor antagonists, steroids, suppression of nitric oxide synthase, various therapeutic approaches, and other recent advances have been developed to mitigate the fatal results of various short-term and chronic adverse events related to CAR T-cell therapy. This study provides a comprehensive perspective on contemporary management strategies and presumed causative processes of CAR T-cell-related adverse effects, albeit with several limitations. When CAR T-cell complications, costs, and challenges of toxicity management are properly considered, the CAR T-cell therapy of the future will include a number of toxicity-escaping options.

Secondary Neutropenias

Neutrophils are a critical component of immunity, particularly against bacteria and other pathogens, but also in inflammation and tissue repair. As a consequence, individuals with neutropenia, defined by a reduction in absolute neutrophil counts, exhibit a strong propensity to severe infections that typically present with muted symptoms. Neutropenias encompass a heterogeneous set of disorders, comprising primary neutropenias, in which specific genes are mutated, and the more common secondary neutropenias, which have diverse non-genetic causes. These include hematological and other cancers, involving both direct effects of the cancer itself and indirect impacts via the chemotherapeutic, biological agents and cell-based approaches used for treatment. Other significant causes of secondary neutropenias are non-chemotherapeutic drugs, autoimmune and other immune diseases, infections and nutrient deficiencies. These collectively act by impacting neutrophil production in the bone marrow and/or destruction throughout the body. This review describes the biological and clinical manifestations of secondary neutropenias, detailing their underlying causes and management, with a discussion of alternative and emerging therapeutic approaches.

Late-onset Neutropenia after Rituximab Treatment for MPO-ANCA-associated Vasculitis

An underestimated side effect of rituximab is late-onset neutropenia (R-LON), which often resolves spontaneously and rarely results in a severe infection. We herein report a case of febrile neutropenia due to R-LON in a 91-year-old woman with renal failure who was treated with rituximab to induce remission of myeloperoxidase antineutrophil cytoplasmic antibodies-associated vasculitis. Fifty-four days after the last rituximab administration, the patient was hospitalized for febrile neutropenia due to R-LON, which improved with granulocyte colony-stimulating factor and antibiotics. Although R-LON may resolve spontaneously and remain unnoticed, it can cause severe infections in the elderly and patients with renal failure.

Development and validation of predictive models of early immune effector cell-associated hematotoxicity

ABSTRACT

Immune effector cell-associated hematotoxicity (ICAHT) is associated with morbidity and mortality after chimeric antigen receptor (CAR) T-cell therapy. To date, the factors associated with ICAHT are poorly characterized, and there is no validated predictive model of ICAHT as defined by current consensus criteria. Therefore, we performed comprehensive univariate analyses to identify factors associated with severe (grade 3-4) early ICAHT (eICAHT) in 691 patients who received commercial or investigational CAR T-cell therapy for hematologic malignancies. In univariate logistic regression, preinfusion factors associated with severe eICAHT included disease type (acute lymphoblastic leukemia), prelymphodepletion (pre-LD) blood counts including absolute neutrophil count (ANC), lactate dehydrogenase (LDH), and inflammatory (C-reactive protein [CRP], ferritin, and interleukin-6 [IL-6]) and coagulopathy biomarkers (D-dimer). Postinfusion laboratory markers associated with severe eICAHT included early and peak levels of inflammatory biomarkers (CRP, ferritin, and IL-6), coagulopathy biomarkers (D-dimer), peak cytokine release syndrome grade, and peak neurotoxicity grade. We trained (n = 483) and validated (n = 208) 2 eICAHT prediction models (eIPMs): eIPMPre including preinfusion factors only (disease type and pre-LD ANC, platelet count, LDH, and ferritin) and eIPMPost containing both preinfusion (disease type and pre-LD ANC, platelet count, and LDH) and early postinfusion (day +3 ferritin) factors. Both models generated calibrated predictions and high discrimination (area under the receiver operating characteristic curve in test set, 0.87 for eIPMPre and 0.88 for eIPMPost), with higher net benefit in decision curve analysis for eIPMPost. Individualized predictions of severe eICAHT can be generated from both eIPMs using our online tool (available at https://eipm.fredhutch.org).

Invasive Fungal Disease After Chimeric Antigen Receptor-T Immunotherapy in Adult and Pediatric Patients

Invasive fungal diseases (IFDs) have been documented among the causes of post-chimeric antigen receptor-T (CAR-T) cell immunotherapy complications, with the incidence of IFDs in CAR-T cell therapy recipients being measured between 0% and 10%, globally. IFDs are notorious for their potentially life-threatening nature and challenging diagnosis and treatment. In this review, we searched the recent literature aiming to examine the risk factors and epidemiology of IFDs post-CAR-T infusion. Moreover, the role of antifungal prophylaxis is investigated. CAR-T cell therapy recipients are especially vulnerable to IFDs due to several risk factors that contribute to the patient's immunosuppression. Those include the underlying hematological malignancies, the lymphodepleting chemotherapy administered before the treatment, existing leukopenia and hypogammaglobinemia, and the use of high-dose corticosteroids and interleukin-6 blockers as countermeasures for immune effector cell-associated neurotoxicity syndrome and cytokine release syndrome, respectively. IFDs mostly occur within the first 60 days following the infusion of the T cells, but cases even a year after the infusion have been described. Aspergillus spp., Candida spp., and Pneumocystis jirovecii are the main cause of these infections following CAR-T cell therapy. More real-world data regarding the epidemiology of IFDs and the role of antifungal prophylaxis in this population are essential.

Basic Concepts and Indications of CAR T Cells

Chimeric antigen receptor (CAR) T cell therapy has revolutionized cancer immunotherapy, particularly for hematological malignancies. This personalized approach is based on genetically engineering T cells derived from the patient to target antigens expressed-among others-on malignant cells. Nowadays they offer new hope where conventional therapies, such as chemotherapy and radiation, have often failed. Since the first FDA approval in 2017, CAR T cell therapy has rapidly expanded, proving highly effective against previously refractory diseases with otherwise a dismal outcome. Despite its promise, CAR T cell therapy continues to face significant challenges, including complex manufacturing, the management of toxicities, resistance mechanisms that impact long-term efficacy, and limited access as well as high costs, which continue to shape ongoing research and clinical applications. This review aims to provide an overview of CAR T cell therapy, including its fundamental concepts, clinical applications, current challenges, and future directions in hematological malignancies.

STOCHASTIC MODELING OF HEMATOPOIETIC STEM CELL DYNAMICS

The study of hematopoietic stem cell (HSCs) maintenance and differentiation to supply the hematopoietic system presents unique challenges, given the complex regulation of the process and the difficulty in observing cellular interactions in the stem cell niche. Quantitative methods and tools have emerged as valuable mechanisms to address this issue; however, the stochasticity of HSCs presents significant challenges for mathematical modeling, especially when bridging the gap between theoretical models and experimental validation. In this work, we have built a flexible and user-friendly stochastic dynamical and spatial model for long-term HSCs (LT-HSCs) and short-term HSCs (ST-HSCs) that captures experimentally observed cellular variability and heterogeneity. Our model implements the behavior of LT-HSCs and ST-HSCs and predicts their homeostatic dynamics. Furthermore, our model can be modified to explore various biological scenarios, such as stress-induced perturbations mediated by apoptosis, and successfully implement these conditions. Finally, the model incorporates spatial dynamics, simulating cell behavior in a 2D environment by combining Brownian motion with spatially graded parameters.

EASIX and m-EASIX predict CRS and ICANS in pediatric and AYA patients after CD19-CAR T-cell therapy

ABSTRACT

Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are complications of CD19-directed chimeric antigen receptor (CD19-CAR) T-cell therapy. The Endothelial Activation and Stress Index (EASIX) and modified EASIX (m-EASIX) scores have been retrospectively proven to be predictive of CRS and ICANS in adult CAR T-cell recipients. However, these scores have not been evaluated in pediatric cohorts. We retrospectively report on 76 pediatric and adolescent and young adult (AYA) patients with relapsed/refractory B-cell acute lymphoblastic leukemia treated with CD19-CAR T cells at St. Jude Children's Research Hospital or Johns Hopkins Hospital. Data included patient, disease, and treatment characteristics. EASIX and m-EASIX scores were calculated at days -5 before, 0, and +3 after CAR T-cell infusion. CRS and ICANS occurred in 47 and 17 patients, respectively. At all evaluated time points, the median EASIX scores were higher for patients who developed severe CRS and any grade ICANS, and the median m-EASIX scores were higher in patients who developed severe CRS and severe ICANS than those with no/mild CRS/ICANS. Receiver operating characteristic curve analysis showed that both scores were strong predictors of CRS, especially severe CRS, at all time points. Any grade and severe ICANS were best predicted by both scores at day +3. m-EASIX uniformly outperformed EASIX, except for predicting any grade ICANS. Our results validate the potential utility of EASIX and m-EASIX scores for predicting CAR T-cell-related complications for pediatric and AYA patients.

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.

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.

[Hematological toxicities post-CAR-T cells: Recommendations of the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

Chimeric antigen receptor T cell (CAR-T cell) therapy has become a standard-of-care for several hematological and a promising treatment for solid malignancies or for selected non-malignant autoimmune disorders. Hematological complications following this treatment are very common with the majority of patients experiencing at least one cytopenia after CAR-T cell injections. The management of these adverse events is not standardized and represents an area of active research and unmet clinical needs. This harmonization workshop, gathering a group of experts who analyzed this topic, has been conceived for the optimization of the management of patients presenting with post-CAR-T cell hematological toxicities. Based on the data present in the literature, these practical recommendations were made to harmonize the practices of Francophone centers involved in the management of these patients.

Prognostic significance of immune reconstitution following CD19 CAR T-cell therapy for relapsed/refractory B-cell lymphoma

Immune deficits after CD19 chimeric antigen receptor (CAR) T-cell therapy can be long-lasting, predisposing patients to infections and non-relapse mortality. In B-cell non-Hodgkin lymphoma (B-NHL), the prognostic impact of immune reconstitution (IR) remains ill-defined, and detailed cross-product comparisons have not been performed to date. In this retrospective observational study, we longitudinally characterized lymphocyte subsets and immunoglobulin levels in 105 B-NHL patients to assess patterns of immune recovery arising after CD19 CAR-T. Three key IR criteria were defined as CD4+ T helper (TH) cells > 200/µL, any detectable B cells, and serum immunoglobulin G (IgG) levels >4 g/L. After a median follow-up of 24.6 months, 38% of patients displayed TH cells, 11% showed any B cells, and 41% had IgG recovery. Notable product-specific differences emerged, including deeper TH cell aplasia with CD28z- versus longer B-cell aplasia with 41BBz-based products. Patients with any IR recovery experienced extended progression-free survival (PFS) (median 20.8 vs. 1.7 months, p < 0.0001) and overall survival (OS) (34.9 vs. 4.0 months, p < 0.0001). While landmark analysis at 90 days confirmed improved PFS in patients with any recovery (34.9 vs. 8.6 months, p = 0.005), no significant OS difference was noted. Notably, 72% of patients with refractory disease never displayed recovery of any IR criteria. Early progressors showed diminished IR at the time of progression/relapse compared to patients with late progression/recurrence (after Day 90). Our results highlight the profound immune deficits observed after CD19 CAR-T and shed light on the intersection of IR and efficacy in B-NHL. Importantly, IR was impaired considerably postprogression, carrying significant implications for subsequent T-cell-engaging therapies and treatment sequencing.

Shift from Widespread to Tailored Antifungal Prophylaxis in Lymphoma Patients Treated with CD19 CAR T Cell Therapy: Results from a Large Retrospective Cohort

Patients undergoing CD19 chimeric antigen receptor (CAR)-T cell therapy exhibit multiple immune deficits that may increase their susceptibility to infections. Invasive fungal infections (IFIs) are life-threatening events in the setting of hematologic diseases. However, there is ongoing debate regarding the optimal role and duration of antifungal prophylaxis in this specific patient population. The objective of this study was to provide a comprehensive overview of the evolution of IFI prophylactic strategies over time and to assess IFI incidence rates in a cohort of patients with relapsed or refractory (R/R) lymphoma treated with CAR-T cell therapy. A single-center retrospective study was conducted on a cohort of patients with R/R B cell lymphoma treated with CD19 CAR-T cell therapy between April 2016 and March 2023. Group A (April 2016-August 2020) consisted of patients primarily treated with fluconazole, irrespective of their individual IFI risk profile. In Group B (September 2020-March 2023) antifungal prophylaxis was recommended only for high-risk patients. Overall, 330 patients were included. Antifungal prophylaxis was prescribed to 119/142 (84%) patients in Group A and 58/188 (31%) in Group B (P < .001). Anti-mold azoles were prescribed to 8 (5.6%) patients in Group A and 21 (11.2%) patients in Group B. In Group A, 42 (29%) patients were switched to another antifungal, 9 (21%) because of toxicity, with 6 cases of transaminitis and 3 cases of prolonged QTc. In Group B, 21 (11.2%) patients were switched to the antifungal drug, mainly from fluconazole or micafungin to a mold-active agent following revised guidelines. No difference was found in liver toxicity between the two groups at infusion, day 10, and day 30. No significant differences were observed between the groups. IFIs following CAR-T cell therapy were rare, with 1 case of cryptococcal meningoencephalitis in group A (.7%) and 1 case of invasive aspergillosis in Group B (.5%), both occurring in patients on micafungin prophylaxis. In this large single-center cohort of patients with R/R lymphoma treated with CAR-T cells, we show that individualized prophylaxis, alongside careful management of CAR-T cell-related toxicities such as CRS, was associated with a very low IFI rate, avoiding the risk of unnecessary toxicities, drug-drug interactions, and high costs.

Comprehensive characterization of cytopenia after chimeric antigen receptor-T cell infusion in patients with relapsed or refractory multiple myeloma

BACKGROUND

Many studies have demonstrated the effectiveness of chimeric antigen receptor-T (CAR-T) cell therapy for relapsed or refractory multiple myeloma (RRMM), but the hematologic toxicity has not been well characterized.

METHODS

A total of 111 adults with RRMM who received BCMA CAR-T cells, BCMA + CD19 CAR-T cells or tandem BCMA/CD19 dual-target (BC19) CAR-T cells infusion were enrolled. We characterized cytopenia and hematologic recovery at different time points after CAR-T-cell therapy, analyzed the effect of cytopenia on prognosis and identified the risk factors.

RESULTS

Patients had a high probability of cytopenia, with anemia, neutropenia and thrombocytopenia occurring in 92%, 95% and 73%, respectively. There were 60 (54%) patients had prolonged hematologic toxicity (PHT) after D28. The median hemoglobin and platelet count were significantly lower at D28 post-CAR-T cell therapy than at baseline. Hemoglobin increased to above baseline at D90. The median absolute neutrophil count was lower than baseline at D0 and D28, and it recovered to baseline at D180. The baseline level of lactate dehydrogenase was associated with thrombocytopenia. Extramedullary involvement was associated with hemoglobin recovery, while the baseline level of albumin and types of CAR-T were related to platelet recovery. Patients with anemia at baseline and at D0, D180 and D360 had shorter progression-free survival (PFS), while anemia at D0, D60, D180 and D360 was associated with shorter overall survival (OS). Neutropenia at D0 was associated with shorter PFS and patients with neutropenia at D90 or D180 had shorter OS. Patients with thrombocytopenia at any time had shorter PFS and OS. Compared to patients without PHT, patients with PHT had shorter PFS and OS.

CONCLUSIONS

The majority of RRMM patients treated with CAR-T cells experienced cytopenia. Cytopenia occurred at specific time points was associated with a poorer prognosis.

The advent of chimeric antigen receptor T Cell therapy in recalibrating immune balance for rheumatic autoimmune disease treatment

CAR-T cell therapy, a cutting-edge cellular immunotherapy with demonstrated efficacy in treating hematologic malignancies, also exhibits significant promise for addressing autoimmune diseases. This innovative therapeutic approach holds promise for achieving long-term remission in autoimmune diseases, potentially offering significant benefits to affected patients. Current targets under investigation for the treatment of these conditions include CD19, CD20, and BCMA, among others. However, CAR-T therapy faces difficulties such as time-consuming cell manufacturing, complex and expensive process, and the possibility of severe adverse reactions complicating the treatment, etc. This article examines CAR-T therapy across various rheumatic autoimmune diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren's syndrome (SS), systemic sclerosis (SSc), antisynthetase syndrome (ASS), and ANCA-associated vasculitis (AAV), highlighting both therapeutic advancements and ongoing challenges.

CARs for lymphoma

Chimeric Antigen Receptor (CAR)-T cell therapy has revolutionized treatment options for B-cell Non-Hodgkin Lymphoma (NHL). CD19-targeting CAR-T cell therapy is approved for treatment in Diffuse Large B Cell Lymphoma, Follicular Lymphoma, Mantle Cell Lymphoma, and Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma. CAR-T cells demonstrate robust and durable responses even in heavily pretreated patients. Clinicians should monitor for Cytokine Release Syndrome (CRS) and Immune Effector Cell Neurotoxicity Syndrome (ICANS), as well as cytopenias, infection, and secondary malignancies. Ongoing questions remain in improving manufacturing efficacy, sequencing CAR-T cells amongst other therapies including bi-specific antibodies (BiTEs), and predicting optimal responders. In addition, novel CARs are being developed with alternative targets or that secrete activating cytokines (i.e. "armored CARs"). CAR-T cells represent an effective lymphoma therapy and should be considered for eligible patients.

Survivorship in Chimeric Antigen Receptor T-Cell Therapy Recipients: Infections, Secondary Malignancies, and Non-Relapse Mortality

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy has significantly advanced the treatment of hematologic malignancies, offering curative potential for patients with relapsed or refractory disease. However, the long-term survivorship of these patients is marked by unique challenges, particularly immune deficits and infectious complications, second primary malignancies (SPMs), and non-relapse mortality (NRM). Understanding and addressing these risks is paramount to improving patient outcomes and quality of life.

SUMMARY

This review explores the incidence and risk factors for NRM and long-term complications following CAR T-cell therapy. Infections are the leading cause of NRM, accounting for over 50% of cases, driven by neutropenia, hypogammaglobulinemia, and impaired cellular immunity. SPMs, including secondary myeloid and T-cell malignancies, are increasingly recognized, prompting the FDA to issue a black box warning, although their direct link to CAR T cells remains disputed. While CAR T-cell-specific toxicities like cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome contribute to morbidity, they represent only a minority of NRM cases. The management of these complications is critical as CAR T-cell therapy is being evaluated for broader use, including in earlier treatment lines and for non-malignant conditions like autoimmune diseases.

KEY MESSAGES

CAR T-cell therapy has revolutionized cancer treatment, but survivorship is complicated by infections, SPMs, and ultimately endangered by NRM. Prophylactic strategies, close monitoring, and toxicity management strategies are key to improving long-term outcomes.

Molecular mechanisms promoting long-term cytopenia after BCMA CAR-T therapy in multiple myeloma

ABSTRACT

Hematologic toxicity is a common side effect of chimeric antigen receptor T-cell (CAR-T) therapies, being particularly severe among patients with relapsed or refractory multiple myeloma (MM). In this study, we characterized 48 patients treated with B-cell maturation antigen (BCMA) CAR-T cells to understand kinetics of cytopenia, identify predictive factors, and determine potential mechanisms underlying these toxicities. We observed that overall incidence of cytopenia was 95.7%, and grade >3 thrombocytopenia and neutropenia, 1 month after infusion, was observed in 57% and 53% of the patients, respectively, being still present after 1 year in 4 and 3 patients, respectively. Baseline cytopenia and high peak inflammatory markers were highly correlated with cytopenia that persisted up to 3 months. To determine potential mechanisms underlying cytopenias, we evaluated the paracrine effect of BCMA CAR-T cells on hematopoietic stem and progenitor cell (HSPC) differentiation using an ex vivo myeloid differentiation model. Phenotypic analysis showed that supernatants from activated CAR-T cells (spCAR) halted HSPC differentiation, promoting more immature phenotypes, which could be prevented with a combination of interferon γ, tumor necrosis factor α/β, transforming growth factor β, interleukin-6 (IL-6) and IL-17 inhibitors. Single-cell RNA sequencing demonstrated upregulation of transcription factors associated with early stages of hematopoietic differentiation in the presence of spCAR (GATA2, RUNX1, CEBPA) and a decrease in the activity of key regulons involved in neutrophil and monocytic maturation (ID2 and MAFB). These results suggest that CAR-T activation induces HSPC maturation arrest through paracrine effects and provides potential treatments to mitigate the severity of this toxicity.

New insights into CAR T-cell hematological toxicities: manifestations, mechanisms, and effective management strategies

Chimeric antigen receptor (CAR) T-cell therapy represents a highly efficacious treatment modality demonstrated to enhance outcomes in patients afflicted with malignancies, particularly those enduring relapsed or refractory hematological malignancies. However, the escalating adoption of CAR T-cell therapy has unveiled several life-threatening toxicities, notably cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), infections, and hematological toxicities (HTs), thereby hindering the broad implementation of CAR T-cell therapy. HTs encompass a spectrum of adverse effects, including cytopenias, hemophagocytic lymphohistiocytosis (HLH), coagulopathies, and B-cell aplasia. While our comprehension of the underlying mechanisms governing CRS and ICANS is advancing, the intricate pathophysiology of HTs remains inadequately elucidated. Such knowledge gaps may precipitate suboptimal therapeutic decisions, potentially culminating in substantial medical resource depletion and detriment to patients' quality of life. In this comprehensive review, based on recent updated findings, we delineate various mechanisms contributing to HTs subsequent to CAR T-cell therapy, explicate manifestations of HTs, and proffer strategic interventions to mitigate this relevant clinical challenge.

Efficacy and risk of donor-derived CAR-T treatment of relapsed B-cell acute lymphoblastic leukemia after hematopoietic stem cell transplantation

The one-year survival rate for patients experiencing a relapse of B-cell acute lymphocytic leukemia (B-ALL) following hematopoietic stem cell transplantation (HSCT) is approximately 30%. Patients experiencing a relapse after allogeneic HSCT frequently encounter difficulties in obtaining autologous CAR-T products. We conducted a study involving 14 patients who received donor-derived CAR-T therapy for relapsed B-ALL following HSCT between August 2019 and May 2023 in our center. The results revealed a CR/CRi rate of 78.6% (11/14), a GVHD rate of 21.4% (3/14), and a 1-year overall survival (OS) rate of 56%. Decreased bone marrow donor cell chimerism in 9 patients recovered after CAR-T therapy. The main causes of death were disease progression and infection. Further analysis showed that GVHD (HR 7.224, 95% CI 1.42-36.82, P = 0.017) and platelet recovery at 30 days (HR 6.807, 95% CI 1.61-28.83, P = 0.009) are significantly associated with OS after CAR-T therapy. Based on the findings, we conclude that donor-derived CAR-T cells are effective in treating relapsed B-ALL patients following HSCT. Additionally, GVHD and poor platelet recovery impact OS, but further verification with a larger sample size is needed.

Best Practice Considerations by The American Society of Transplant and Cellular Therapy: Infection Prevention and Management After Chimeric Antigen Receptor T Cell Therapy for Hematological Malignancies

Chimeric antigen receptor (CAR) T-cell therapy is rapidly advancing, offering promising treatments for patients with hematological malignancy. However, associated infectious complications remain a significant concern because of their contribution to patient morbidity and non-relapse mortality. Recent epidemiological insights shed light on risk factors for infections after CAR T-cell therapy. However, the available evidence is predominantly retrospective, highlighting a need for further prospective studies. Institutions are challenged with managing infections after CAR T-cell therapy but variations in the approaches taken underscore the importance of standardizing infection prevention and management protocols across different healthcare settings. Therefore, the Infectious Diseases Special Interest Group of the American Society of Transplantation and Cellular Therapy assembled an expert panel to develop best practice considerations. The aim was to guide healthcare professionals in optimizing infection prevention and management for CAR T-cell therapy recipients and advocates for early consultation of Infectious Diseases during treatment planning phases given the complexities involved. By synthesizing current evidence and expert opinion these best practice considerations provide the basis for understanding infection risk after CAR T-cell therapies and propose risk-mitigating strategies in children, adolescents, and adults. Continued research and collaboration will be essential to refining and effectively implementing these recommendations.

Mobilizing CARs: Benefits, drawbacks, and directions for outpatient CAR T-cell therapy

Chimeric antigen receptor T-cell (CAR-T) therapy has heralded a new era in the treatment of various hematological malignancies, increasingly being utilized in earlier lines of therapy. Moreover, cellular therapies are currently under investigation for their potential in treating solid malignancies and autoimmune disorders. As the scope of indications for CAR-T therapy continues to expand, along with the associated reductions in costs and hospital admissions, many medical centers are transitioning towards outpatient CAR-T models. Moreover, ongoing efforts to mitigate complications such as cytokine release syndrome (CRS) or neurotoxicity include the development of premedication strategies, prompt management of adverse events, and the advancement of newer, safer CAR-T cell therapies. However, despite these advancements, the inherent risk of these life-threatening complications remains a critical concern in CAR-T therapy. Institutions must diligently anticipate and effectively manage these complications to ensure the safety and well-being of patients undergoing CAR-T therapy. This includes establishing robust protocols for timely identification and intervention of adverse events, and seamless pathways for transitioning patients to a higher level of care if necessary. This review provides an overview of the current landscape of outpatient CAR-T therapy and offers essential insights into the key clinical and operational considerations needed to implement a successful outpatient CAR-T program.

Mesenchymal stem cell infusion for enhancing hematopoietic recovery and addressing cytopenias in CAR-T cell therapy

BACKGROUND

Chimeric antigen receptor (CAR)-T therapy has emerged as a promising treatment for hematologic malignancies. However, cytopenia remains one of the most frequent and challenging adverse effects of this therapy.

METHODS

We conducted a retrospective analysis of 26 patients with relapsed/refractory aggressive B-cell lymphoma who received CAR-T therapy at our center. Subsequently, to investigate measures to address cytopenias following CAR-T therapy, we isolated and generated murine CAR-T cells and bone marrow-derived mesenchymal stem cells (MSCs), establishing a murine syngeneic CAR-T therapy model. We assessed the impact of MSC infusion on hematopoietic recovery post-CAR-T therapy by evaluating complete blood count, bone marrow hematopoietic stem cells and their subpopulations, bone marrow histomorphology, and hematopoiesis-related genes.

RESULTS

All patients experienced cytopenias to varying degrees, with complete lineage involvement in half of the patients. Grade ≥ 3 cytopenias were observed in 88.46% of the patients. CAR-T therapy was associated with a higher incidence of biphasic, late-onset, or prolonged cytopenias. Survival analysis indicated that neutropenia and lymphopenia tended to be associated with better prognosis, whereas thrombocytopenia tended to be related to poorer outcomes. Through animal experiments, we discovered that MSCs infusion boosted HSCs and their long-term subpopulations, enhancing hematopoietic recovery, particularly in the megakaryocyte lineage, and mitigating bone marrow damage. Importantly, both in vitro and in vivo experiments demonstrated that MSCs did not compromise the activity or antitumor efficacy of CAR-T cells.

CONCLUSIONS

Our findings propose MSCs infusion as a promising strategy to address cytopenias, particularly thrombocytopenia, after CAR-T therapy. This approach could help overcome certain limitations of cellular immunotherapy by enhancing hematopoietic recovery without compromising the efficacy of CAR-T cells.

HIGHLIGHTS

1 Cytopenia is a frequently observed adverse effect following CAR-T therapy, and it is often characterized by biphasic and prolonged patterns. 2 MSCs play a critical role in promoting hematopoietic recovery and mitigating bone marrow damage in a murine model of CAR-T therapy 3 The activity and antitumor efficacy of CAR-T cells were not impaired by MSCs.

A Multicenter Real-life Prospective Study of Axicabtagene Ciloleucel versus Tisagenlecleucel Toxicity and Outcomes in Large B-cell Lymphomas

This real-world prospective observational study across 21 Italian centers (CART-SIE) compares axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) outcomes in 485 patients with relapsed/refractory large B-cell lymphoma with baseline characteristics matched by stabilized inverse propensity score weighting. Axi-cel versus tisa-cel had higher all-grade cytokine release syndrome (78.6% vs. 89.3%, P = 0.0017) and neurotoxicity (9.9% vs. 32.2%, P < 0.0001) but also superior progression-free survival (PFS) at 1 year (46.5% vs. 34.1%, P = 0.0009). Even among patients who failed bridging therapy, axi-cel PFS was superior to tisa-cel (37.5% vs. 22.7%, P = 0.0059). Differences in overall survival and high-grade immune toxicities were not significant. The CAR-HEMATOTOX score not only predicted hematologic toxicity but also 1-year survival outcomes (51.5% in CAR-HEMATOTOX high vs. 77.2% in CAR-HEMATOTOX low, P < 0.0001). Twenty patients developed second primary malignancies, including two cases of T-cell neoplasms. These findings enable more informed selection of anti-CD19 CAR T-cell therapy, balancing bridging, safety, and efficacy considerations for individual patients. Significance: The findings of this study on 485 patients with relapsed/refractory large B-cell lymphoma treated with commercial axi-cel and tisa-cel indicate axi-cel's superior PFS after propensity score weighting. The predictive utility of CAR-HEMATOTOX in assessing not only toxicity but also outcomes across both CAR T-cell products may guide future risk-stratified management strategies.

Management of chimeric antigen receptor T (CAR-T) cell-associated toxicities

The use of chimeric antigen receptor T (CAR-T) cells is a significant therapeutic improvement increasing the prognosis for patients with a variety of hematological malignancies. However, this therapy has also sometimes life-threatening, complications. Therefore, knowledge of the treatment and management of these complications, especially in treatment centers and intensive care units, respectively, is of outstanding importance. This review provides recommendations for the diagnosis, management, and treatment of CAR-T cell-associated complications such as cytokine release syndrome, immune effector cell associated neurotoxicity syndrome, hematotoxicity, hypogammaglobulinemia, and CAR-T cell-induced pseudo-progression amongst others for physicians treating patients with CAR-T cell-associated complications and intensivists.

Prolonged cytopenias after immune effector cell therapy and lymphodepletion in patients with leukemia, lymphoma and solid tumors

BACKGROUND AIMS

The success of chimeric antigen receptor (CAR) T-cell therapy in treating B-cell malignancies has led to the evaluation of CAR T-cells targeting a variety of other malignancies. Although the efficacy of CAR T-cells is enhanced when administered post-lymphodepleting chemotherapy, this can trigger bone marrow suppression and sustained cytopenia after CD19.CAR T-cell therapy. Additionally, systemic inflammation associated with CAR T-cell activity may contribute to myelosuppression. Cytopenias, such as neutropenia and thrombocytopenia, elevate the risk of severe infections and bleeding, respectively. However, data on the incidence of prolonged cytopenias after immune effector therapy in the solid tumor context remain limited.

OBJECTIVE

We compared the incidence of prolonged cytopenias after immune effector therapy including genetically modified T-cells, virus-specific T-cells (VSTs) and NKT-cells, as well non-gene-modified VSTs for leukemia, lymphoma, and solid tumors (ST) to identify associated risk factors.

METHODS

A retrospective analysis was conducted of 112 pediatric and adult patients with relapsed and/or refractory cancers who received lymphodepleting chemotherapy followed by immune effector therapy. Patients treated with 13 distinct immune effector cell therapies through 11 single-center clinical trials and 2 commercial products over a 6-year period were categorized into 3 types of malignancies: leukemia, lymphoma and ST. We obtained baseline patient characteristics and adverse events data for each participant, and tracked neutrophil and platelet counts following lymphodepletion.

RESULTS

Of 112 patients, 104 (92.9%) experienced cytopenias and 88 (79%) experienced severe cytopenias. Patients with leukemia experienced significantly longer durations of severe neutropenia (median duration of 14 days) compared with patients with lymphoma (7 days) or ST (11 days) (P = 0.002). Patients with leukemia also had a higher incidence of severe thrombocytopenia (74.1%), compared with lymphoma (46%, P = 0.03) and ST (14.3%, P < 0.0001). Prolonged cytopenias were significantly associated with disease type (63% of patients with leukemia, 44% of patients with lymphoma, and 22.9% of patients with ST, P = 0.006), prior hematopoietic stem cell transplant (HSCT) (66.7% with prior HSCT versus 38.3% without prior HSCT, P = 0.039), and development of immune effector cell-associated neurotoxicity syndrome (ICANS) (75% with ICANS versus 38% without ICANS, P = 0.027). There was no significant association between prolonged cytopenias and cytokine release syndrome.

CONCLUSIONS

Immune effector recipients often experience significant cytopenias due to marrow suppression following lymphodepletion regardless of disease, but prolonged severe cytopenias are significantly less common after treatment of patients with lymphoma and solid tumors.

Use of Eltrombopag to Improve Thrombocytopenia and Tranfusion Requirement in Anti-CD19 CAR-T Cell-Treated Patients

Background/Objectives: Immune effector cell-associated hematotoxicity (ICAHT) is a frequent adverse event after chimeric antigen receptor (CAR)-T cell therapy. Grade ≥ 3 thrombocytopenia occurs in around one-third of patients, and many of them become platelet transfusion-dependent. Eltrombopag is a thrombopoietin receptor agonist (TPO-RA) able to accelerate megakaryopoiesis, which has been used successfully in patients with bone marrow failure and immune thrombocytopenia (ITP). Its role in managing thrombocytopenia and other cytopenias in CAR-T cell-treated patients has been scarcely addressed. Our aim was to report the safety and efficacy of this approach in patients included in the Spanish Group for Hematopoietic Transplantation and Cellular Therapy (GETH-TC) registry. Methods: This is a retrospective, multicenter, observational study. Patients who developed platelet transfusion dependence subsequently to CAR-T cells and received eltrombopag to improve platelet counts were recruited in 10 Spanish hospitals. Results: Thirty-eight patients were enrolled and followed up for a median (interquartile range [IQR]) of 175 (99, 489) days since CAR-T cell infusion. At the moment eltrombopag was indicated, 18 patients had thrombocytopenia and another severe cytopenia, while 8 patients had severe pancytopenia. After 32 (14, 38) days on eltrombopag, 29 (76.3%) patients recovered platelet transfusion independence. The number of platelet units transfused correlated with the time needed to restore platelet counts higher than 20 × 109/L (Rho = 0.639, p < 0.001). Non-responders to eltrombopag required more platelet units (58 [29, 69] vs. 12 [6, 26] in responders, p = 0.002). Nineteen out of twenty-three (82.6%) patients recovered from severe neutropenia after 22 (11, 31) days on eltrombopag. Twenty-nine out of thirty-five (82.9%) patients recovered red blood cell (RBC) transfusion independence after 29 (17, 44) days. Seven patients recovered all cell lineages while on treatment. No thromboembolic events were reported. Only two transient toxicities (cholestasis, hyperbilirubinemia) were reported during eltrombopag treatment, none of which compelled permanent drug withdrawal. Conclusions: Eltrombopag could be safely used to manage thrombocytopenia and accelerate transfusion independence in CAR-T cell-treated patients.

Systemic toxicity of CAR-T therapy and potential monitoring indicators for toxicity prevention

Malignant tumors of the hematologic system have a high degree of malignancy and high mortality rates. Chimeric antigen receptor T cell (CAR-T) therapy has become an important option for patients with relapsed/refractory tumors, showing astonishing therapeutic effects and thus, it has brought new hope to the treatment of malignant tumors of the hematologic system. Despite the significant therapeutic effects of CAR-T, its toxic reactions, such as Cytokine Release Syndrome (CRS) and Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS), cannot be ignored since they can cause damage to multiple systems, including the cardiovascular system. We summarize biomarkers related to prediction, diagnosis, therapeutic efficacy, and prognosis, further exploring potential monitoring indicators for toxicity prevention. This review aims to summarize the effects of CAR-T therapy on the cardiovascular, hematologic, and nervous systems, as well as potential biomarkers, and to explore potential monitoring indicators for preventing toxicity, thereby providing references for clinical regulation and assessment of therapeutic effects.

Cell-Based Treatment in Acute Myeloid Leukemia Relapsed after Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplant (ASCT) remains the only treatment option for patients with high-risk acute myeloid leukemia (AML). Recurrence of leukemic cells after ASCT represents a dramatic event associated with a dismal outcome, with a 2-year survival rate of around 20%. Adoptive cell therapy (ACT) is a form of cell-based strategy that has emerged as an effective therapy to treat and prevent post-ASCT recurrence. Lymphocytes are the principal cells used in this therapy and can be derived from a hematopoietic stem cell donor, the patient themselves, or healthy donors, after being engineered to express the chimeric antigen receptor (CAR-T and UniCAR-T). In this review, we discuss recent advances in the established strategy of donor lymphocyte infusion (DLI) and the progress and challenges of CAR-T cells.

Romiplostim in chemotherapy-induced thrombocytopenia: A review of the literature

Chemotherapy-induced thrombocytopenia (CIT) is a common challenge of cancer therapy and can lead to chemotherapy dose reduction, delay, and/or discontinuation, affecting relative dose intensity, and possibly adversely impacting cancer care. Besides changing anticancer regimens, standard management of CIT has been limited to platelet transfusions and supportive care. Use of the thrombopoietin receptor agonist romiplostim, already approved for use in immune thrombocytopenia, has shown promising signs of efficacy in CIT. In a phase 2 prospective randomized study of solid tumor patients with platelet counts <100 × 109/L for ≥4 weeks due to CIT, weekly romiplostim corrected the platelet count to >100 × 109/L in 93% (14/15) of patients within 3 weeks versus 12.5% (1/8) of untreated patients (p < 0.001). Including patients treated with romiplostim in an additional single-arm cohort, 85% (44/52) of all romiplostim-treated patients responded with platelet count correction within 3 weeks. Several retrospective studies of CIT have also shown responses to weekly romiplostim, with the largest study finding that poor response to romiplostim was predicted by tumor invasion of the bone marrow (odds ratio, 0.029; 95% CI: 0.0046-0.18; p < 0.001), prior pelvic irradiation (odds ratio, 0.078; 95% CI: 0.0062-0.98; p = 0.048), and prior temozolomide treatment (odds ratio 0.24; 95% CI: 0.061-0.96; p = 0.043). Elsewhere, lower baseline TPO levels were predictive of romiplostim response (p = 0.036). No new safety signals have emerged from romiplostim CIT studies. Recent treatment guidelines, including those from the National Comprehensive Cancer Network, now support consideration of romiplostim use in CIT. Data are expected from two ongoing phase 3 romiplostim CIT trials.

Current understanding and management of CAR T cell-associated toxicities

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of several haematological malignancies and is being investigated in patients with various solid tumours. Characteristic CAR T cell-associated toxicities such as cytokine-release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are now well-recognized, and improved supportive care and management with immunosuppressive agents has made CAR T cell therapy safer and more feasible than it was when the first regulatory approvals of such treatments were granted in 2017. The increasing clinical experience with these therapies has also improved recognition of previously less well-defined toxicities, including movement disorders, immune effector cell-associated haematotoxicity (ICAHT) and immune effector cell-associated haemophagocytic lymphohistiocytosis-like syndrome (IEC-HS), as well as the substantial risk of infection in patients with persistent CAR T cell-induced B cell aplasia and hypogammaglobulinaemia. A more diverse selection of immunosuppressive and supportive-care pharmacotherapies is now being utilized for toxicity management, yet no universal algorithm for their application exists. As CAR T cell products targeting new antigens are developed, additional toxicities involving damage to non-malignant tissues expressing the target antigen are a potential hurdle. Continued prospective evaluation of toxicity management strategies and the design of less-toxic CAR T cell products are both crucial for ongoing success in this field. In this Review, we discuss the evolving understanding and clinical management of CAR T cell-associated toxicities.

Chimeric antigen receptor T-cell therapy for aggressive B-cell lymphomas

Chimeric antigen receptor (CAR) T-cell therapy is a revolutionary approach in the treatment of lymphoma. This review article provides an overview of the four FDA-approved CAR T-cell products for aggressive B-cell lymphoma, including diffuse large B-cell lymphoma and mantle cell lymphoma, highlighting their efficacy and toxicity as well as discussing future directions.

Activated CD4+ T Cell Proportion in the Peripheral Blood Correlates with the Duration of Cytokine Release Syndrome and Predicts Clinical Outcome after Chimeric Antigen Receptor T Cell Therapy

Objective Chimeric antigen receptor (CAR) T cell therapy is an emerging and effective therapy for relapsed or refractory diffuse large B cell lymphoma (R/R DLBCL). The characteristic toxicities of CAR T cell therapy include cytokine release syndrome (CRS) and prolonged cytopenia. We investigated the factors associated with these complications after CAR T cell therapy by analyzing lymphocyte subsets following CAR T cell infusion. Methods We retrospectively analyzed peripheral blood samples on days 7, 14, and 28 after tisagenlecleucel (tisa-cel) infusion by flow cytometry at our institution between June 2020 and September 2022. Patients Thirty-five patients with R/R DLBCL who received tisa-cel therapy were included. Results A flow cytometry-based analysis of blood samples from these patients revealed that the proportion of CD4+CD25+CD127+ T cells (hereafter referred to as "activated CD4+ T cells" ) among the total CD4+ T cells on day 7 after tisa-cel infusion correlated with the duration of CRS (r=0.79, p<0.01). In addition, a prognostic analysis of the overall survival (OS) using time-dependent receiver operating characteristic curves indicated a significantly more favorable OS and progression-free survival of patients with a proportion of activated CD4+ T cells among the total CD4+ T cells <0.73 (p=0.01, and p<0.01, respectively). Conclusion These results suggest that the proportion of activated CD4+ T cells on day 7 after tisa-cel infusion correlates with the CRS duration and predicts clinical outcomes after CAR T cell therapy. Further studies with a larger number of patients are required to validate these observations.

Development and validation of an automated computational approach to grade immune effector cell-associated hematotoxicity

Hematologic toxicity frequently complicates chimeric antigen receptor (CAR) T-cell therapy, resulting in significant morbidity and mortality. In an effort to standardize reporting, the European Hematology Association (EHA) and European Society of Blood and Marrow Transplantation (EBMT) devised the immune effector cell-associated hematotoxicity (ICAHT) grading system, distinguishing between early (day 0-30) and late (after day +30) events based on neutropenia depth and duration. However, manual implementation of ICAHT grading criteria is time-consuming and susceptible to subjectivity and error. To address these challenges, we introduce a novel computational approach, utilizing the R programming language, to automate early and late ICAHT grading. Given the complexities of early ICAHT grading, we benchmarked our approach both manually and computationally in two independent cohorts totaling 1251 patients. Our computational approach offers significant implications by streamlining grading processes, reducing manual time and effort, and promoting standardization across varied clinical settings. We provide this tool to the scientific community alongside a comprehensive implementation guide, fostering its widespread adoption and enhancing reporting consistency for ICAHT.

A meta-analysis to assess the risk of bleeding and thrombosis following chimeric antigen receptor T-cell therapy: Communication from the ISTH SSC Subcommittee on Hemostasis and Malignancy

BACKGROUND

Chimeric antigen receptor T-cell (CAR T-cell) therapy is increasingly utilized for treatment of hematologic malignancies. Hematologic toxicities including thrombosis and bleeding complications have been reported. Accurate estimates for thrombotic and bleeding outcomes are lacking.

OBJECTIVES

We performed a systematic review and meta-analysis in patients who received CAR T-cell therapy for an underlying hematologic malignancy with the objective to: a) assess the thrombosis and bleeding risk associated with CAR T-cell therapy, b) assess the impact of CRS and ICANS on the risks of thrombosis and bleeding, and c) assess the safety of anticoagulant or antiplatelet use in the period following treatment with CAR T-cell therapy.

METHODS

We searched MEDLINE, EMBASE, and Cochrane CENTRAL up to February 2022 for studies reporting thrombotic or bleeding outcomes in patients receiving CAR T-cell therapy. Pooled event rates were calculated using a random-effects model. We performed subgroup analyses stratified by follow-up duration, CAR T-cell target antigen, and underlying hematologic malignancy.

RESULTS

We included 47 studies with a total of 7040 patients. High heterogeneity between studies precluded reporting of overall pooled rates of thrombotic and bleeding events. In studies with follow-up duration of ≤6 months, the pooled incidence of venous thrombotic events was 2.4% (95% CI, 1.4%-3.4%; I2 = 0%) per patient-month, whereas the rate was 0.1% (95% CI, 0%-0.1%; I2 = 0%) per patient-month for studies with longer follow-up periods (>6 months). The pooled incidences of any bleeding events per patient-month in studies with follow-up duration of ≤6 months and >6 months were 1.9% (95% CI, 0.6%-3.1%; I2 = 78%) and 0.3% (95% CI: 0%-0.8%, I2 = 40%), respectively. Secondary analyses by CAR T-cell target antigen, underlying malignancy, and primary outcome of the studies did not reveal significant differences in the rates of thromboembolism, any bleeding events, or major bleeding events.

CONCLUSION

The risk of both thrombosis and bleeding following CAR T-cell therapy appears to be highest in the initial months following infusion.