Parameters of long‐term response with CD28 ‐based CD19 chimaeric antigen receptor‐modified T cells in children and young adults with B‐acute lymphoblastic leukaemia

Impact of pre-infusion disease burden on outcomes in pediatric relapsed/refractory B-cell lymphoblastic leukemia following anti-CD19 CAR T-cell therapy

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapies have demonstrated high efficacy in pediatric patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Despite this success, the challenge of post-infusion relapse persists. In our study, we evaluate 116 children with R/R B-ALL who received anti-CD19 CAR T-cell therapy at our center. All patients were included in the response analysis and assessed for survival and toxicity. The CR rate was 98.3%, with 90.5% achieving minimal residual disease negative (MRD)- CR by day 28 (d28). The overall survival (OS) and event-free survival (EFS) were 69.3%±4.5% and 59.0%±4.6%, respectively, with a median follow-up duration of 47.9 months. The patients with pre-infusion MRD ≥ 1% was associated with lower 4-year OS (p = 0.006) and EFS (p = 0.027) comparing to those with MRD < 1%. The incidences of grade ≥ 3 cytokine release syndrome (CRS) and neurotoxicity were21.6 and 5.0%, respectively. Therefore, pre-infusion disease burden is a predictor of long-term outcome following anti-CD19 CAR T-cell therapy for pediatric R/R B-ALL.

Improved CAR-T cell activity associated with increased mitochondrial function primed by galactose

CD19 CAR-T cells have led to durable remissions in patients with refractory B-cell malignancies; nevertheless, most patients eventually relapse in the long term. Many interventions aimed at improving current products have been reported, with a subset of them focusing on a direct or indirect link to the metabolic state of the CAR-T cells. We assessed clinical products from an ongoing clinical trial utilizing CD19-28z CAR-T cells from patients with acute lymphoblastic leukemia. CAR-T clinical products leading to a complete response had significantly higher mitochondrial function (by oxygen consumption rate) irrespective of mitochondrial content. Next, we replaced the carbon source of the media from glucose to galactose to impact cellular metabolism. Galactose-containing media increased mitochondrial activity in CAR-T cells, and improved in in-vitro efficacy, without any consistent phenotypic change in memory profile. Finally, CAR-T cells produced in galactose-based glucose-free media resulted in increased mitochondrial activity. Using an in-vivo model of Nalm6 injected mice, galactose-primed CAR-T cells significantly improved leukemia-free survival compared to standard glucose-cultured CAR-T cells. Our results prove the significance of mitochondrial metabolism on CAR-T cell efficacy and suggest a translational pathway to improve clinical products.

Advances in research on factors affecting chimeric antigen receptor T-cell efficacy

Chimeric antigen receptor T-cell (CAR-T) therapy is becoming an effective technique for the treatment of patients with relapsed/refractory hematologic malignancies. After analyzing patients with tumor progression and sustained remission after CAR-T cell therapy, many factors were found to be associated with the efficacy of CAR-T therapy. This paper reviews the factors affecting the effect of CAR-T such as tumor characteristics, tumor microenvironment and immune function of patients, CAR-T cell structure, construction method and in vivo expansion values, lymphodepletion chemotherapy, and previous treatment, and provides a preliminary outlook on the corresponding therapeutic strategies.

The new era of immunological treatment, last updated and future consideration of CAR T cell-based drugs

Cancer treatment is one of the fundamental challenges in clinical setting, especially in relapsed/refractory malignancies. The novel immunotherapy-based treatments bring new hope in cancer therapy and achieve various treatment successes. One of the distinguished ways of cancer immunotherapy is adoptive cell therapy, which utilizes genetically modified immune cells against cancer cells. Between different methods in ACT, the chimeric antigen receptor T cells have more investigation and introduced a promising way to treat cancer patients. This technology progressed until it introduced six US Food and Drug Administration-approved CAR T cell-based drugs. These drugs act against hematological malignancies appropriately and achieve exciting results, so they have been utilized widely in cell therapy clinics. In this review, we introduce all CAR T cells-approved drugs based on their last data and investigate them from all aspects of pharmacology, side effects, and compressional. Also, the efficacy of drugs, pre- and post-treatment steps, and expected side effects are introduced, and the challenges and new solutions in CAR T cell therapy are in the last speech.

CAR-T Cell Therapy in B-Cell Acute Lymphoblastic Leukemia

Treatment of refractory and relapsed (R/R) B acute lymphoblastic leukemia (B-ALL) is an unmet medical need in both children and adults. Studies carried out in the last two decades have shown that autologous T cells engineered to express a chimeric antigen receptor (CAR-T) represent an effective technique for treating these patients. Antigens expressed on B-cells, such as CD19, CD20, and CD22, represent targets suitable for treating patients with R/R B-ALL. CD19 CAR-T cells induce a high rate (80-90%) of complete remissions in both pediatric and adult R/R B-ALL patients. However, despite this impressive rate of responses, about half of responding patients relapse within 1-2 years after CAR-T cell therapy. Allo-HSCT after CAR-T cell therapy might consolidate the therapeutic efficacy of CAR-T and increase long-term outcomes; however, not all the studies that have adopted allo-HSCT as a consolidative treatment strategy have shown a benefit deriving from transplantation. For B-ALL patients who relapse early after allo-HSCT or those with insufficient T-cell numbers for an autologous approach, using T cells from the original stem cell donor offers the opportunity for the successful generation of CAR-T cells and for an effective therapeutic approach. Finally, recent studies have introduced allogeneic CAR-T cells generated from healthy donors or unmatched, which are opportunely manipulated with gene editing to reduce the risk of immunological incompatibility, with promising therapeutic effects.

Cerebral Spinal Fluid Parameters Following CD19-Targeted Therapies in Children and Young Adults

The presence of leukocytes in the cerebral spinal fluid (CSF) of patients with acute lymphoblastic leukemia may indicate a relapse in the central nervous system. CD19-directed immunotherapy may increase the blood-brain barrier permeability, leading to neurologic toxicity and infiltrate the CNS. We studied the CSF cell and protein content in 71 consecutive patients who received either CD19 chimeric antigen receptor T cells or blinatumomab. Responding patients had an incidence of 66% and 61% of pleocytosis following blinatumomab or chimeric antigen receptor T cells, respectively. CSF parameters did not correlate with toxicity or prior CNS disease. Routine CSF flow cytometry following immunotherapy to distinguish T-cell infiltration from CNS relapse should be considered.

Preventing relapse after CD19 CAR T-cell therapy for pediatric ALL: the role of transplant and enhanced CAR T cells

CD19-specific chimeric antigen receptor (CAR) T-cell therapy has become an integral part of our treatment armamentarium for pediatric patients with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL). However, despite initial remission rates of greater than 80%, durable remission occurs in only 40% to 50% of patients. In this review we summarize our current knowledge of the role of consolidative hematopoietic cell transplantation in the management of pediatric patients who achieved a minimal residual disease-negative complete response post CD19 CAR T-cell therapy. In addition, we review approaches to enhance effector function CD19 CAR T cells, focusing on how to improve persistence and prevent the emergence of CD19- B-ALL blasts.

Leukapheresis for CAR-T cell production and therapy

Chimeric antigen receptor (CAR) T-cell therapy is an effective, individualized immunotherapy, and novel treatment for hematologic malignancies. Six commercial CAR-T cell products are currently approved for lymphatic malignancies and multiple myeloma. In addition, an increasing number of clinical centres produce CAR-T cells on-site, which enable the administration of CAR-T cells on site. The CAR-T cell products are either fresh or cryopreserved. Manufacturing CAR-T cells is a complicated process that begins with leukapheresis to obtain T cells from the patient's peripheral blood. An optimal leukapheresis product is crucial step for a successful CAR-T cell therapy; therefore, it is imperative to understand the factors that may affect the quality or T cells. The leukapheresis for CAR-T cell production is well tolerated and safe for both paediatric and adult patients and CAR-Τ cell therapy presents high clinical response rate in many studies. CAR-T cell therapy is under continuous improvement, and it has transformed into an almost standard procedure in clinical haematology and stem cell transplantation facilities that provide both autologous and allogeneic stem cell transplantations. In patients suffering from advanced haematological malignancies, CAR-T cell therapy shows incredible antitumor efficacy. Even after a single infusion of autologous CD19-targeting CAR-T cells in patients with relapsed or refractory diffuse large B cell lymphoma (DLBCL) and acute lymphoblastic leukaemia (ALL), long lasting remission is observed, and a fraction of the patients are being cured. Future novel constructs are being developed with better T cell persistence and better expansion. New next-generation CAR-T cells are currently designed to avoid toxicities such as cytokine release syndrome and neurotoxicity.

Assessment and predictive ability of the absolute neutrophil count in peripheral blood for in vivo CAR T cells expansion and CRS

BACKGROUND

Chimeric antigen receptor (CAR) T cell therapy is an advanced and effective immunotherapy for relapsed or refractory B-cell malignancies. High expansion of CAR T cells in vivo and durable antitumor activity indicate a persistent therapeutic response. However, this treatment is linked to a high frequency of adverse events, such as cytokine release syndrome (CRS), which affects its efficacy and can even be life-threatening. At present, a variety of markers associated with clinical response and treatment toxicity after CAR T cells infusion have been reported. Although these biomarkers can act as effective indicators reflecting CAR T cells expansion as well as CRS, they fail to predict the expansion rate of CAR T cells. Hence, further investigation is urgent to find a new biomarker to fill this void.

METHODS

We analyzed the association between the absolute neutrophil count (ANC) and CAR expansion and CRS in 45 patients with B-cell malignancies from two clinical trials. We proposed that ANC could be a practical biomarker for CAR T cells expansion and CRS, and conducted a feasibility analysis on its predictive ability.

RESULTS

In this study, 17 B-cell hematological malignancy patients with anti-B-cell maturation antigen CAR-treated and 28 with CAR19/22 T-cell-treated were enrolled and divided into an ANC-absence group and an ANC-presence group. The results showed that ANC absence correlated positively with CAR expansion and the expansion rate. The ANC can be used as a predictive marker for CAR T cells expansion. Moreover, the patients with ANC absence experienced a more severe CRS, and ANC performed a predictive ability for CRS. In addition, the peak serum concentration of several cytokines involved in CRS was higher in patients with ANC absence.

CONCLUSION

Thus, we suggest ANC as an evaluative and predictive biomarker for CAR expansion and CRS during CAR T cell therapy, which can help to maximize clinical efficacy, reduce treatment-related toxicity and prolong survival.

Intrinsic tumor resistance to CAR T cells is a dynamic transcriptional state that is exploitable with low-dose radiation

Chimeric antigen receptor (CAR) T-cell therapy represents a major advancement for hematologic malignancies, with some patients achieving long-term remission. However, the majority of treated patients still die of their disease. A consistent predictor of response is tumor quantity, wherein a higher disease burden before CAR T-cell therapy portends a worse prognosis. Focal radiation to bulky sites of the disease can decrease tumor quantity before CAR T-cell therapy, but whether this strategy improves survival is unknown. We find that substantially reducing systemic tumor quantity using high-dose radiation to areas of bulky disease, which is commonly done clinically, is less impactful on overall survival in mice achieved by CAR T cells than targeting all sites of disease with low-dose total tumor irradiation (TTI) before CAR T-cell therapy. This finding highlights another predictor of response, tumor quality, the intrinsic resistance of an individual patient's tumor cells to CAR T-cell killing. Little is known about whether or how an individual tumor's intrinsic resistance may change under different circumstances. We find a transcriptional "death receptor score" that reflects a tumor's intrinsic sensitivity to CAR T cells can be temporarily increased by low-dose TTI, and the timing of this transcriptional change correlates with improved in vivo leukemia control by an otherwise limited number of CAR T cells. This suggests an actionable method for potentially improving outcomes in patients predicted to respond poorly to this promising therapy and highlights that intrinsic tumor attributes may be equally or more important predictors of CAR T-cell response as tumor burden.

Improved CAR-T cell activity associated with increased mitochondrial function primed by galactose

CD19 CAR-T cells have led to durable remissions in patients with refractory B-cell malignancies; nevertheless, most patients eventually relapse in the long term. Many interventions aimed at improving current products have been reported, with a subset of them focusing on a direct or indirect link to the metabolic state of the CAR-T cells. We assessed clinical products from an ongoing clinical trial utilizing CD19-28z CAR-T cells from patients with acute lymphoblastic leukemia. CAR-T clinical products leading to a complete response had significantly higher mitochondrial function (by oxygen consumption rate) irrespective of mitochondrial content. Next, we replaced the carbon source of the media from glucose to galactose to impact cellular metabolism. Galactose-containing media increased mitochondrial activity in CAR-T cells, and improved in vitro efficacy, without any consistent phenotypic change in memory profile. Finally, CAR-T cells produced in galactose-based glucose-free media resulted in increased mitochondrial activity. Using an in vivo model of Nalm6 injected mice, galactose-primed CAR-T cells significantly improved leukemia-free survival compared to standard glucose-cultured CAR-T cells. Our results prove the significance of mitochondrial metabolism on CAR-T cell efficacy and suggest a translational pathway to improve clinical products.

Current status of CAR-T cell therapy for pediatric hematologic malignancies

Acute lymphoblastic leukemia (ALL) is the most common cancer in the pediatric population, and the long-term survival can reach 90%. However, approximately, 20% of pediatric ALL patients experience relapse and require second-line chemotherapy. This is frequently followed by hematopoietic stem cell transplantation, which can cause long-term sequelae. Recent advances in immunotherapy, such as monoclonal antibody therapy and chimeric antigen receptor (CAR)-T cell therapy, have revolutionized the treatment of relapsed and refractory ALL. Anti-CD19 CAR-T cells successfully eliminate B cell malignancies such as ALL. Tisagenlecleucel (Kymriah^®) is the first CAR-T cell immunotherapy approved by the FDA. CAR-T cell therapy can cause specific adverse events (AEs) such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, which are defined and graded according to the consensus grading system and treated with supportive therapies along with tocilizumab and corticosteroids. Other AEs include prolonged bone marrow suppression and hypogammaglobulinemia. Severe AEs are less common in the real-world experience than in clinical trials, probably due to better management of the patient before and during CAR-T cell therapy. The biggest challenge in CAR-T cell therapy against ALL is relapse. A high tumor burden on infusion, early loss of B cell aplasia, and minimal residual disease positivity after CAR-T cell infusion are predictive of relapse. Consolidative stem cell transplantation may improve the long-term outcome. The success of CD19 CAR-T cell therapy against B cell malignancy prompted extensive research into the use of CAR-T cells against other hematologic malignancies such as T cell leukemia or myeloid leukemia.

Long-term outcomes following CAR T cell therapy: what we know so far

Chimeric antigen receptors (CAR) are engineered fusion proteins designed to target T cells to antigens expressed on cancer cells. CAR T cells are now an established treatment for patients with relapsed and/or refractory B cell lymphomas, B cell acute lymphoblastic leukaemia and multiple myeloma. At the time of this writing, over a decade of follow-up data are available from the initial patients who received CD19-targeted CAR T cells for B cell malignancies. Data on the outcomes of patients who received B cell maturation antigen (BCMA)-targeted CAR T cells for multiple myeloma are more limited owing to the more recent development of these constructs. In this Review, we summarize long-term follow-up data on efficacy and toxicities from patients treated with CAR T cells targeting CD19 or BCMA. Overall, the data demonstrate that CD19-targeted CAR T cells can induce prolonged remissions in patients with B cell malignancies, often with minimal long-term toxicities, and are probably curative for a subset of patients. By contrast, remissions induced by BCMA-targeted CAR T cells are typically more short-lived but also generally have only limited long-term toxicities. We discuss factors associated with long-term remissions, including the depth of initial response, malignancy characteristics predictive of response, peak circulating CAR levels and the role of lymphodepleting chemotherapy. We also discuss ongoing investigational strategies designed to improve the length of remission following CAR T cell therapy.

ASTCT Committee on Practice Guidelines Survey on Evaluation & Management of Diffuse Large B-cell Lymphoma after Failure of Chimeric Antigen Receptor T Cell Therapy (CAR-T) Therapy

Chimeric antigen receptor T-cell therapy (CAR-T) is a major advance in managing aggressive relapsed or refractory B-cell lymphomas; however, relapses are frequent and pose a major therapeutic challenge. There is substantial variability across transplantation and cellular therapy programs in assessing and managing post-CAR-T failures. The American Society for Transplantation and Cellular Therapy Committee on Practice Guidelines conducted an online cross-sectional survey between August 2021 and October 2021 to determine the U.S. lymphoma and transplantation and cellular therapy physicians' practice patterns for the detection and diagnosis of CAR-T failure, as well as management strategies for diffuse large B-cell lymphoma in this particular setting. E-mail surveys were sent to 901 potential participants, of which 174 (19%) completed the survey. Responders were mainly White (51.2%), male (70.7%), and with >10 years of practice experience (51.2%). Overall, 87% of the responders were affiliated with university/teaching centers; 54.6% had general oncology practices, and 45.4% had lymphoma-focused transplantation/cellular therapy practices. The most common periods to perform surveillance scans were at 3 months and 12 months after CAR-T infusion. Overall, 88.5% of responders would often or always consider a biopsy to confirm relapse and 89% would routinely check for the persistence of the antigen targeted by the CAR (e.g., CD19 in the case of CD19 CAR-T). The most popular first salvage regimen for relapse or progression was an alternate CAR-T therapy (dual or alternate target) regardless of CD19 positivity. Twenty-seven percent of responders chose this regimen for CD19 positive relapse, whereas 31% of responders did so for CD19 negative relapse. Overall, 88.5% of responders favored consolidative allogeneic hematopoietic cell transplantation after response to salvage, whereas 51.2% of physicians would consider autologous hematopoietic cell transplantation in transplantation-naïve patients. There is substantial cross-center variation in surveillance, diagnosis, and management of CAR-T failure. Prospective clinical trials evaluating novel agents in this setting are urgently needed to identify best management strategies.