Survival outcomes and efficacy of autologous CD19 chimeric antigen receptor-T cell therapy in the patient with diagnosed hematological malignancies: a systematic review and meta-analysis

Implications of Immunotherapy for Pediatric Malignancies: A Summary from the APSA Cancer Committee

Although survival for many pediatric cancers has improved with advances in conventional chemotherapeutic regimens and surgical techniques in the last several decades, it remains a leading cause of disease-related death in children. Outcomes in patients with recurrent, refractory, or metastatic disease are especially poor. Recently, the advent of alternative classes of therapies, including immunotherapies, have revolutionized systemic treatment for pediatric malignancies. Several classes of immunotherapies, including chimeric antigen receptor (CAR) T cell therapy, transgenic T-cell receptor (TCR)-T cell therapy, bispecific T-cell engagers, and monoclonal antibody checkpoint inhibitors have been FDA-approved or entered early-phase clinical trials in children and young adults. The pediatric surgeon is likely to encounter these therapies during the care of children with malignancies and should be familiar with the classes of therapy, indications, adverse events, and potential need for surgical intervention in these cases. This review from the APSA Cancer Committee offers a brief discussion of the three most encountered classes of immunotherapy in children and young adults and discusses surgical relevance. LEVEL OF EVIDENCE: IV.

Assessment of anti-CD20 antibody pre-treatment for augmentation of CAR-T cell therapy in SIV-infected rhesus macaques

During chronic HIV and SIV infections, the majority of viral replication occurs within lymphoid follicles. In a pilot study, infusion of SIV-specific CD4-MBL-CAR-T cells expressing the follicular homing receptor, CXCR5, led to follicular localization of the cells and a reduction in SIV viral loads in rhesus macaques. However, the CAR-T cells failed to persist. We hypothesized that temporary disruption of follicles would create space for CAR-T cell engraftment and lead to increased abundance and persistence of CAR-T cells. In this study we treated SIV-infected rhesus macaques with CAR-T cells and preconditioned one set with anti-CD20 antibody to disrupt the follicles. We evaluated CAR-T cell abundance and persistence in four groups of SIVmac239-infected and ART-suppressed animals: untreated, CAR-T cell treated, CD20 depleted, and CD20 depleted/CAR-T cell treated. In the depletion study, anti-CD20 was infused one week prior to CAR-T infusion and cessation of ART. Anti-CD20 antibody treatment led to temporary depletion of CD20+ cells in blood and partial depletion in lymph nodes. In this dose escalation study, there was no impact of CAR-T cell infusion on SIV viral load. However, in both the depleted and non-depleted animals, CAR-T cells accumulated in and around lymphoid follicles and were Ki67+. CAR-T cells increased in number in follicles from 2 to 6 days post-treatment, with a median 15.2-fold increase in follicular CAR-T cell numbers in depleted/CAR-T treated animals compared to an 8.1-fold increase in non-depleted CAR-T treated animals. The increase in CAR T cells in depleted animals was associated with a prolonged elevation of serum IL-6 levels and a rapid loss of detectable CAR-T cells. Taken together, these data suggest that CAR-T cells likely expanded to a greater extent in depleted/CAR-T cell treated animals. Further studies are needed to elucidate mechanisms mediating the rapid loss of CAR-T cells and to evaluate strategies to improve engraftment and persistence of HIV-specific CAR-T cells. The potential for an inflammatory cytokine response appears to be enhanced with anti-CD20 antibody treatment and future studies may require CRS control strategies. These studies provide important insights into cellular immunotherapy and suggest future studies for improved outcomes.

CAR-T cell therapy for patients with hematological malignancies. A systematic review

Hematological malignancies represent defying clinical conditions, with high levels of morbidity and mortality, particularly considering patients who manifest multiple refractory disease. Recently, chimeric antigen receptor (CAR)-T cell therapy has emerged as a potential treatment option for relapsed/refractory B cell malignancies, which have motivated Food and Drug Administration approval of a series of products based on this technique. The objective of this systematic review was to assess the efficacy and safety of CAR-T cell therapy for patients with hematological malignancies. A comprehensive literature search was conducted in the electronic databases (CENTRAL, Embase, LILACS and MEDLINE), clinical trials register platforms (Clinicaltrials.gov and WHO-ICTRP) and grey literature (OpenGrey). The Cochrane Handbook for Reviews of Interventions was used for developing the review and the PRISMA Statement for manuscript reporting. The protocol was prospectively published in PROSPERO database (CRD42020181047). After the selection process, seven RCTs were included, three of which with available outcome results. The available results are from studies assessing axicabtagene, lisocabtagene and tisagenlecleucel for patients with B cell lymphoma, and the certainty of evidence ranged from very low to low for survival and progression-related outcome and for safety outcomes. Additionally, four randomized controlled trials comparing CAR-T cell therapy to the standard treatment for various types of relapsed/refractory B cell non-Hodgkin lymphomas and multiple myeloma included in this systematic review still did not have available outcome data. The results of this review may be used to guide clinical practice but evidence concerning safety and efficacy of CAR-T Cell therapy for hematological malignancies is still immature to recommend its application outside of clinical trials or compassionate use context for advanced and terminal cases. It is expected the results of the referred comparative studies will provide further elements to subsidize broader application of this immunotherapy. This article is protected by copyright. All rights reserved.

Efficacy and Safety of CAR-T Cell Products Axicabtagene Ciloleucel, Tisagenlecleucel, and Lisocabtagene Maraleucel for the Treatment of Hematologic Malignancies: A Systematic Review and Meta-Analysis

Background

Currently, three chimeric antigen receptor (CAR)-T cell products axicabtagene ciloleucel, tisagenlecleucel, and lisocabtagene maraleucel have been approved by the U.S. Food and Drug Administration for the treatment of large B cell lymphoma, which provide a novel and promising choice for patients with relapsed or refractory to traditional anti-tumor treatments. Thus, it is pertinent to describe the efficacy and safety profile of the three products available by summarizing the current evidence.

Methods

Two reviewers independently searched the Embase, PubMed, Web of Science, and Cochrane Library, to identify studies related to the use of the three CAR-T cell products for treating hematologic malignancies published up to October 5, 2020. We pooled the overall response rate, complete response rate, cytokine release syndrome, and immune effector cell-associated neurotoxicity syndrome of three products, and then performed subgroup analysis based on the type of product and type of tumor.

Results

Thirty-three studies involving 2,172 patients were included in the analysis. All three products showed promising results in patients with different pathological subtypes and clinical characteristics that included those who did not meet the eligibility criteria of licensing trials, with overall response rates of nearly 70% or above and complete response rates of more than 50%. However, high rates of severe immune effector cell-associated neurotoxicity syndrome in patients undergoing axicabtagene ciloleucel treatment and life-threatening cytokine release syndrome in patients with leukemia undergoing tisagenlecleucel treatment required special attention in practice (31%; 95% CI: 0.27–0.35 and 55%; 95% CI: 0.45–0.64, respectively). Moreover, lisocabtagene maraleucel that showed a favorable efficacy and safety in the licensing trial lacked corresponding real-world data.

Conclusion

Both axicabtagene ciloleucel and tisagenlecleucel showed considerable efficacy in practice, but need special attention with respect to life-threatening toxicity that can occur in certain situations. Lisocabtagene maraleucel demonstrated excellent efficacy and safety profiles in the licensing trial, but lacked corresponding real-world data. Additional data on the three products are needed in rare histological subtypes to benefit a broader patient population.

The role of small molecules in cell and gene therapy

Cell and gene therapies have achieved impressive results in the treatment of rare genetic diseases using gene corrected stem cells and haematological cancers using chimeric antigen receptor T cells. However, these two fields face significant challenges such as demonstrating long-term efficacy and safety, and achieving cost-effective, scalable manufacturing processes. The use of small molecules is a key approach to overcome these barriers and can benefit cell and gene therapies at multiple stages of their lifecycle. For example, small molecules can be used to optimise viral vector production during manufacturing or used in the clinic to enhance the resistance of T cell therapies to the immunosuppressive tumour microenvironment. Here, we review current uses of small molecules in cell and gene therapy and highlight opportunities for medicinal chemists to further consolidate the success of cell and gene therapies.

The Influence of Chimeric Antigen Receptor Structural Domains on Clinical Outcomes and Associated Toxicities

Chimeric antigen receptor (CAR)-T cell therapy has transformed the treatment of B cell malignancies, improving patient survival and long-term remission. Nonetheless, over 50% of patients experience severe treatment-related toxicities including cytokine release syndrome (CRS) and neurotoxicity. Differences in severity of toxic side-effects among anti-CD19 CARs suggest that the choice of costimulatory domain makes a significant contribution to toxicity, but comparisons are complicated by additional differences in the hinge and transmembrane (TM) domains of the most commonly used CARs in the clinic, segments that have long been considered to perform purely structural roles. In this perspective, we examine clinical and preclinical data for anti-CD19 CARs with identical antigen-binding (FMC63) and signalling (CD3ζ) domains to unravel the contributions of different hinge-TM and costimulatory domains. Analysis of clinical trials highlights an association of the CD28 hinge-TM with higher incidence of CRS and neurotoxicity than the corresponding sequences from CD8, regardless of whether the CD28 or the 4-1BB costimulatory domain is used. The few preclinical studies that have systematically varied these domains similarly support a strong and independent role for the CD28 hinge-TM sequence in high cytokine production. These observations highlight the value that a comprehensive and systematic interrogation of each of these structural domains could provide toward developing fundamental principles for rational design of safer CAR-T cell therapies.

T Cell Activation Machinery: Form and Function in Natural and Engineered Immune Receptors

The impressive success of chimeric antigen receptor (CAR)-T cell therapies in treating advanced B-cell malignancies has spurred a frenzy of activity aimed at developing CAR-T therapies for other cancers, particularly solid tumors, and optimizing engineered T cells for maximum clinical benefit in many different disease contexts. A rapidly growing body of design work is examining every modular component of traditional single-chain CARs as well as expanding out into many new and innovative engineered immunoreceptor designs that depart from this template. New approaches to immune cell and receptor engineering are being reported with rapidly increasing frequency, and many recent high-quality reviews (including one in this special issue) provide comprehensive coverage of the history and current state of the art in CAR-T and related cellular immunotherapies. In this review, we step back to examine our current understanding of the structure-function relationships in natural and engineered lymphocyte-activating receptors, with an eye towards evaluating how well the current-generation CAR designs recapitulate the most desirable features of their natural counterparts. We identify key areas that we believe are under-studied and therefore represent opportunities to further improve our grasp of form and function in natural and engineered receptors and to rationally design better therapeutics.

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.