Chimeric Antigen Receptor T Cells for B-Cell Acute Lymphoblastic Leukemia

Adverse events and efficacy of second-round CAR-T cell therapy in relapsed pediatric B-ALL

OBJECTIVE

Chimeric antigen receptor (CAR) T-cell therapy has transformed the treatment approach for pediatric patients suffering from relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, there was a paucity of data on the challenges associated with second-round CAR-T therapy in this population.

METHODS

Medical records of nine pediatric patients who received second-round CAR-T therapy in a single center from June 2019 to May 2023 were analyzed. Throughout the course of the clinical trial, we evaluated adverse events including CRS, CRES, infections, hematologic toxicity, and organ injury, as well as CAR-T responses.

RESULTS

Except for one patient who chose CART therapy due to testicular relapse, the remaining patients had indications for CAR-T therapy due to relapse with bone marrow alone or combined with other site. There were no difference between the transfusion dose of CART1 and CART2. No differences of incidence and grade of CRS was found between the first-round CAR-T therapy (CART1) and second-round CAR-T therapy (CART2). Additionally, we found that the incidence of CRES was higher for CART1(3/9,33.3%) than CART2(1/9,11.1%). Our findings revealed that there were no differences of IL-2, IL-4, IL-6, IL-10, IFN-γ, and TNF-α between CART1 and CART2, but the peak level of IL-17A was significantly higher in patients receiving CART1 compared to those receiving CART2 (p = .011). Early and late infection rates after CART1 were higher than CART2. Based on the dynamic changes of ANC, hemoglobin and platelet, ANC, and platelet were reduced obviously post CART. It seems that the incidences of severe thrombocytopenia and severe anemia were higher in the CART1 group compared to CART2. The MRD-negative CR rates for CART1 and CART2 are 100% and 44.4%, respectively (p = .029). All patients experienced events (relapse, chemotherapy, transplantation, or death) after receiving CART2, including one died, three discharged automatically, and the remaining five patients survived.

CONCLUSION

Although the remission rate of CART2 is not as high as the CART1 due to the severity of the disease, its safety regarding CRS, CRES, infections, and organ injury is still excellent. Therefore, CART2 remains a viable option for treating pediatric relapsed B-ALL.

How should childhood acute lymphoblastic leukemia relapses in low-income and middle-income countries be managed: The AHOPCA-ALL study group experience

BACKGROUND

Children with relapsed acute lymphoblastic leukemia (ALL) in low-income and middle-income countries rarely survive. The Pediatric Hematology-Oncology Association of Central America (AHOPCA) developed the AHOPCA-ALL REC 2014 protocol to improve outcomes in resource-constrained settings without access to stem cell transplantation.

METHODS

The AHOPCA-ALL REC 2014 protocol was based on a modified frontline induction phase 1A, a consolidation therapy with six modified R-blocks derived from the ALL-Berlin-Frankfurt-Munster REZ 2002 protocol and intermittent maintenance therapy. Children with B-lineage ALL were eligible after a late medullary relapse, an early or late combined relapse, or any extramedullary relapses. Those with T-lineage ALL were eligible after early and late extramedullary relapses, as were those with both B-lineage and T-lineage relapses occurring at least 3 months after therapy abandonment.

RESULTS

The study population included 190 patients with T-lineage (n = 3) and B-lineage (n = 187) ALL. Of those with B-lineage ALL, 25 patients had a very early extramedullary relapse, 40 had an early relapse (32 extramedullary and 8 combined), and 125 had a late relapse (34 extramedullary, 19 combined, and 72 medullary). The main cause of treatment failure was second relapse (52.1%). The 3-year event-free survival rate (± standard error) was 25.9% ± 3.5%, and the 3-year overall survival rate was 36.7% ± 3.8%. The 3-year event-free survival rate was 47.2% ± 4.7% for late relapses. The most frequently reported toxicity was grade 3 or 4 infection. Mortality during treatment occurred in 17 patients (8.9%), in most cases because of infectious complications.

CONCLUSIONS

Selected children with relapsed ALL in Central America can be cured with second-line regimens even without access to consolidation with stem cell transplantation. Children in low-income and middle-income countries who have lower risk relapses of ALL should be treated with curative intent.

CAR-T therapy followed by allogeneic hematopoietic stem cell transplantation for refractory/relapsed acute B lymphocytic leukemia: Long-term follow-up results

Background

Patients with refractory/relapsed (r/r) acute B lymphocytic leukemia (B-ALL) can achieve complete response (CR) after chimeric antigen receptor T-cell (CAR-T) therapy, but recurrence occurs in the short term. To reduce recurrence and improve survival, CAR-T therapy followed by transplantation is a feasible option. We analyzed the long-term follow-up outcomes and the risk factors for allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CR by CAR-T therapy in this study.

Methods

A total of 144 patients who underwent allo-HSCT after CAR-T therapy in our hospital were enrolled in this study. Target gene analysis was performed in 137 r/r B-ALL patients receiving allo-HSCT after CR by CAR-T therapy. Among the 137 patients, 87 were evaluated for germline predisposition gene mutations, and 92 were evaluated for tumor somatic gene mutations using NGS. The clinical factors, germline predisposition gene and somatic gene mutations associated with the prognosis of patients receiving transplantation after CAR-T therapy were analyzed using univariate Cox regression. Factors related to disease-free survival (DFS) and overall survival (OS) were analyzed using multivariate Cox regression analysis.

Results

In 137 r/r B-ALL patients, the 2-year cumulative incidence of recurrence (CIR), OS and DFS in patients receiving allo-HSCT after CAR-T therapy was 31.5%, 71.4%, and 60.5%, respectively. The 2-year OS and DFS in MRD-negative patients were 80.9% and 69.3%, respectively. Univariate Cox analysis showed that pretransplant MRD positivity, fungal infection, germline EP300 mutation and somatic TP53 mutation were associated with a poor prognosis after transplantation; a TBI-based regimen was a protective factor for survival and recurrence after transplantation. Multivariate Cox regression analysis showed that the TBI-based regimen was an independent protective factor for DFS, fungal infection and MRD positivity were independent risk factors for DFS, and tumor somatic TP53 mutation and germline EP300 mutation were independent risk factors for DFS and OS.

Conclusion

Germline EP300 mutation and tumor somatic TP53 mutation are poor prognostic factors for posttransplant recurrence and survival in r/r B-ALL patients achieving CR after CAR-T therapy. The prognostic risk factors should be considered in adjusting treatment strategies to improve the efficacy of clinical diagnosis and treatment.

Next-day manufacture of a novel anti-CD19 CAR-T therapy for B-cell acute lymphoblastic leukemia: first-in-human clinical study

To improve clinical outcomes and shorten the vein-to-vein time of chimeric antigen receptor T (CAR-T) cells, we developed the FasT CAR-T (F-CAR-T) next-day manufacturing platform. We report the preclinical and first-in-human clinical studies evaluating the safety, feasibility, and preliminary efficacy of CD19 F-CAR-T in B-cell acute lymphoblastic leukemia (B-ALL). CD19 F-CAR-T cells demonstrated excellent proliferation with a younger cellular phenotype, less exhaustion, and more effective tumor elimination compared to conventional CAR-T cells in the preclinical study. In our phase I study (NCT03825718), F-CAR-T cells were successfully manufactured and infused in all of the 25 enrolled pediatric and adult patients with B-ALL. CD19 F-CAR-T safety profile was manageable with 24% grade 3 cytokine release syndrome (CRS) and 28% grade 3/4 neurotoxicity occurring predominantly in pediatric patients. On day 14, 23/25 patients achieved minimal residual disease (MRD)-negative complete remission (CR), and 20 subsequently underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) within 3 months post F-CAR-T therapy. Fifteen of 20 patients were disease-free with a median remission duration of 734 days. One patient relapsed and 4/20 died from transplant-related mortality. Of the three patients who did not undergo allo-HSCT, two remained in CR until 10 months post-F-CAR-T. Our data indicate that anti-CD19 FasT CAR-T shows promising early efficacy for B-ALL. Further evaluations in larger clinical studies are needed.

Optimizing rAAV6 transduction of primary T cells for the generation of anti-CD19 AAV-CAR-T cells

Recombinant Adeno-associated virus(rAAV) is currently the most widely used gene delivery vector and has been successfully used in various disease models, benefiting from its low immunogenicity, almost no toxicity, and no reported pathogenicity in humans. However, its low transduction efficiency for primary cells, especially for T lymphocytes, limits its further application in the field of cell therapy. In this study, we optimized the protocol for rAAV6 transduction of primary T cells, significantly improved the expression efficiency of the rAAV6 delivered CAR gene, and successfully generated rAAV6-based CAR-T cells (AAV-CAR-T). The gene expression intensity (mean fluorescence intensity, MFI) of rAAV6 transduced T cells treated with the tyrosine kinase inhibitor, Genistein, was increased 1-3-fold. Moreover, our results showed that rAAV6 efficiently transduced T cells stimulated with OKT3 and the gene expression could be enhanced 3-fold with an OKT3 concentration of 50 ng/mL in the medium. The gene expression intensity of T cells treated with OKT3 together with genistein could be augmented by 7-fold. Based on the above-optimized method, CAR-T cells prepared with rAAV6 showed evident anti-tumor ability both in vitro and in vivo. Our findings established an efficient method for the AAV transduction of T cells and would provide an alternative way for the preparation of CAR-T cells.

Fibroblast Activation Protein-α as a Target in the Bench-to-Bedside Diagnosis and Treatment of Tumors: A Narrative Review

Fibroblast activation protein-α (FAP) is a type II integral serine protease that is specifically expressed by activated fibroblasts. Cancer-associated fibroblasts (CAFs) in the tumor stroma have an abundant and stable expression of FAP, which plays an important role in promoting tumor growth, invasion, metastasis, and immunosuppression. For example, in females with a high incidence of breast cancer, CAFs account for 50–70% of the cells in the tumor’s microenvironment. CAF overexpression of FAP promotes tumor development and metastasis by influencing extracellular matrix remodeling, intracellular signaling, angiogenesis, epithelial-to-mesenchymal transition, and immunosuppression. This review discusses the basic biological characteristics of FAP and its applications in the diagnosis and treatment of various cancers. We review the emerging basic and clinical research data regarding the use of nanomaterials that target FAP.

Utilizing the prognostic impact of minimal residual disease in treatment decisions for pediatric acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the first pediatric cancer where the assessment of early response to therapy by minimal residual disease (MRD) monitoring has demonstrated its importance to improve risk-based treatment approaches. The most standardized tools to study MRD in ALL are multiparametric flow cytometry and realtime-quantitative polymerase chain reaction amplification-based methods. In recent years, MRD measurement has reached greater levels of sensitivity and standardization through international laboratory networks collaboration.

AREAS COVERED

We herewith describe how to assess and apply the prognostic impact of MRD in treatment decisions, with specific focus on pediatric ALL. We also highlight the role of MRD monitoring in the context of genetically homogeneous subgroups of pediatric ALL. However, some queries remain to be addressed and emerging technologies hold the promise of improving MRD detection in ALL patients.

EXPERT OPINION

Emerging technologies, like next generation flow cytometry, droplet digital PCR, and next generation sequencing appear to be important methods for assessing MRD in pediatric ALL. These more specific and/or sensitive MRD monitoring methods may help to predict relapse with greater accuracy, and are currently being used in clinical trials to improve pediatric ALL outcome by optimizing patient stratification and earlier MRD-based interventional therapy.

Chimeric antigen receptor T cell therapies for acute myeloid leukemia

Chimeric antigen receptor T cell (CAR T) therapies have achieved unprecedented efficacy in B-cell tumors, prompting scientists and doctors to exploit this strategy to treat other tumor types. Acute myeloid leukemia (AML) is a group of heterogeneous myeloid malignancies. Relapse remains the main cause of treatment failure, especially for patients with intermediate or high risk stratification. Allogeneic hematopoietic stem cell transplantation could be an effective therapy because of the graft-versus-leukemia effect, which unfortunately puts the patient at risk of serious complications, such as graft-versus-host disease. Although the identification of an ideal target antigen for AML is challenging, CAR T therapy remains a highly promising strategy for AML patients, particularly for those who are ineligible to receive a transplantation or have positive minimal residual disease. In this review, we focus on the most recent and promising advances in CAR T therapies for AML.

Biomarkers in individualized management of chimeric antigen receptor T cell therapy

The development of chimeric antigen receptor (CAR) T cell immunotherapy has achieved promising results, both in clinical studies and in commercial products for patients with hematologic malignancies. Despite high remission rates of CAR-T cell therapy in previously untreatable, refractory and/or relapsed patients, several challenges in CAR-T therapy remain to be overcome, especially in integrating such therapies into personalized disease management approaches. Given the unique characteristics of CAR-T therapy, it is particularly urgent to identify biomarkers to maximize their clinical benefits. This systematic review summarizes clinically relevant biomarkers that may help individualized disease management in patients receiving CAR-T cell therapy in terms of toxicity warning, efficacy prediction and relapse monitoring. We summarize data from 18 clinical trials, including traditional indicators like cytokines, biochemical proteins, tumor burden, as well as potential novel indicators such as CAR-T cell expansion and persistency. The establishment of a biomarker-based system aimed at individualized management is recommended to guide better clinical application of CAR-T products.