Impact of high-risk cytogenetics on outcomes for children and young adults receiving CD19-directed CAR T-cell therapy.

Chimeric antigen receptor (CAR) T-cell therapy can induce durable remissions of relapsed/refractory B-acute lymphoblastic leukemia (ALL). However, case reports suggested differential outcomes mediated by leukemia cytogenetics. We identified children and young adults with relapsed/refractory CD19+ ALL/lymphoblastic lymphoma treated on 5 CD19-directed CAR T-cell (CTL019 or humanized CART19) clinical trials or with commercial tisagenlecleucel from April 2012 to April 2019. Patients were hierarchically categorized according to leukemia cytogenetics: High-risk lesions were defined as KMT2A (MLL) rearrangements, Philadelphia chromosome (Ph+), Ph-like, hypodiploidy, or TCF3/HLF; favorable as hyperdiploidy or ETV6/RUNX1; and intermediate as iAMP21, IKZF1 deletion, or TCF3/PBX1. Of 231 patients aged 1 to 29, 74 (32%) were categorized as high risk, 28 (12%) as intermediate, 43 (19%) as favorable, and 86 (37%) as uninformative. Overall complete remission rate was 94%, with no difference between strata. There was no difference in relapse-free survival (RFS; P = .8112), with 2-year RFS for the high-risk group of 63% (95% confidence interval [CI], 52-77). There was similarly no difference seen in overall survival (OS) (P = .5488), with 2-year OS for the high-risk group of 70% (95% CI, 60-82). For patients with KMT2A-rearranged infant ALL (n = 13), 2-year RFS was 67% (95% CI, 45-99), and OS was 62% (95% CI, 40-95), with multivariable analysis demonstrating no increased risk of relapse (hazard ratio, 0.70; 95% CI, 0.21-2.90; P = .7040) but a higher proportion of relapses associated with myeloid lineage switch and a 3.6-fold increased risk of all-cause death (95% CI, 1.04-12.75; P = .0434). CTL019/huCART19/tisagenlecleucel are effective at achieving durable remissions across cytogenetic categories. Relapsed/refractory patients with high-risk cytogenetics, including KMT2A-rearranged infant ALL, demonstrated high RFS and OS probabilities at 2 years.

Single-cell multiomics reveals increased plasticity, resistant populations, and stem-cell-like blasts in KMT2A-rearranged leukemia.

KMT2A-rearranged (KMT2A-r) infant acute lymphoblastic leukemia (ALL) is a devastating malignancy with a dismal outcome, and younger age at diagnosis is associated with increased risk of relapse. To discover age-specific differences and critical drivers that mediate poor outcome in KMT2A-r ALL, we subjected KMT2A-r leukemias and normal hematopoietic cells from patients of different ages to single-cell multiomics analyses. We uncovered the following critical new insights: leukemia cells from patients <6 months have significantly increased lineage plasticity. Steroid response pathways are downregulated in the most immature blasts from younger patients. We identify a hematopoietic stem and progenitor-like (HSPC-like) population in the blood of younger patients that contains leukemic blasts and form an immunosuppressive signaling circuit with cytotoxic lymphocytes. These observations offer a compelling explanation for the ability of leukemias in young patients to evade chemotherapy and immune-mediated control. Our analysis also revealed preexisting lymphomyeloid primed progenitors and myeloid blasts at initial diagnosis of B-ALL. Tracking of leukemic clones in 2 patients whose leukemia underwent a lineage switch documented the evolution of such clones into frank acute myeloid leukemia (AML). These findings provide critical insights into KMT2A-r ALL and have clinical implications for molecularly targeted and immunotherapy approaches. Beyond infant ALL, our study demonstrates the power of single-cell multiomics to detect tumor intrinsic and extrinsic factors affecting rare but critical subpopulations within a malignant population that ultimately determines patient outcome.

Cellular therapy: Immune-related complications.

The advent of chimeric antigen receptor T (CAR-T) and the burgeoning field of cellular therapy has revolutionized the treatment of relapsed/refractory leukemia and lymphoma. This personalized "living therapy" is highly effective against a number of malignancies, but this efficacy is tempered by side effects relatively unique to immunotherapies, including CAR-T. The overwhelming release of cytokines and chemokines by activated CAR-T and other secondarily activated immune effector cells can lead to cytokine release syndrome (CRS), which can have clinical and pathophysiology similarities to systemic inflammatory response syndrome and macrophage activating syndrome/hemophagocytic lymphohistiocytosis. Tocilizumab, an anti-IL6 receptor antibody, was recently FDA approved for treatment of CRS after CAR-T based on its ability to mitigate CRS in many patients. Unfortunately, some patients are refractory and additional therapies are needed. Patients treated with CAR-T can also develop neurotoxicity and, as the biology is poorly understood, current therapeutic interventions are limited to supportive care. Nevertheless, a number of recent studies have shed new light on the pathophysiology of CAR-T-related neurotoxicity, which will hopefully lead to effective treatments. In this review we discuss some of the mechanistic contributions intrinsic to the CAR-T construct, the tumor being treated, and the individual patient that impact the development and severity of CRS and neurotoxicity. As CAR-T and cellular therapy have redefined the concept of personalized medicine, so too will personalization be necessary in managing the unique side effects of these therapies.

A cellular antidote to specifically deplete anti-CD19 chimeric antigen receptor-positive cells.

Unintentional transduction of B-cell acute lymphoblastic leukemia blasts during CART19 manufacturing can lead to CAR19+ leukemic cells (CARB19) that are resistant to CART19 killing. We developed an anti-CAR19 idiotype chimeric antigen receptor (αCAR19) to specifically recognize CAR19+ cells. αCAR19 CAR T cells efficiently lysed CARB19 cells in vitro and in a primary leukemia-derived xenograft model. We further showed that αCAR19-CART cells could be used as an "antidote" to deplete CART19 cells to reduce long-term side effects, such as B-cell aplasia.

Human Adenovirus 7-Associated Hemophagocytic Lymphohistiocytosis-like Illness: Clinical and Virological Characteristics in a Cluster of Five Pediatric Cases.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of immune dysregulation. Children often suffer from primary genetic forms of HLH, which can be triggered by infection. Others suffer from secondary HLH as a complication of infection, malignancy, or rheumatologic disease. Identifying the exact cause of HLH is crucial, as definitive treatment for primary disease is hematopoietic stem cell transplant. Adenoviruses have been associated with HLH but molecular epidemiology data are lacking. METHODS: We describe the clinical and virologic characteristics of 5 children admitted with adenovirus infection during 2018-2019 who developed HLH or HLH-like illness. Detailed virologic studies, including virus isolation and comprehensive molecular typing were performed. RESULTS: All patients recovered; clinical management varied but included immunomodulating and antiviral therapies. A genetic predisposition for HLH was not identified in any patient. Adenovirus isolates were recovered from 4/5 cases; all were identified as genomic variant 7d. Adenovirus type 7 DNA was detected in the fifth case. Phylogenetic analysis of genome sequences identified 2 clusters-1 related to strains implicated in 2016-2017 outbreaks in Pennsylvania and New Jersey, the other related to a 2009 Chinese strain. CONCLUSIONS: It can be challenging to determine whether HLH is the result of an infectious pathogen alone or genetic predisposition triggered by an infection. We describe 5 children from the same center presenting with an HLH-like illness after onset of adenovirus type 7 infection. None of the patients were found to have a genetic predisposition to HLH. These findings suggest that adenovirus 7 infection alone can result in HLH.

Partially CD3+-Depleted Unrelated and Haploidentical Donor Peripheral Stem Cell Transplantation Has Favorable Graft-versus-Host Disease and Survival Rates in Pediatric Hematologic Malignancy.

Most children who may benefit from stem cell transplantation lack a matched related donor. Alternative donor transplantations with an unrelated donor (URD) or a partially matched related donor (PMRD) carry an increased risk of graft-versus-host-disease (GVHD) and mortality compared with matched related donor transplantations. We hypothesized that a strategy of partial CD3+/CD19+ depletion for URD or PMRD peripheral stem cell transplantation (PSCT) would attenuate the risks of GVHD and mortality. We enrolled 84 pediatric patients with hematologic malignancies at the Children's Hospital of Philadelphia and the Children's Hospital of Wisconsin between April 2005 and February 2015. Two patients (2.4%) experienced primary graft failure. Relapse occurred in 23 patients (27.4%; cumulative incidence 26.3%), and 17 patients (20.2%) experienced nonrelapse mortality (NRM). Grade III-IV acute GVHD was observed in 18 patients (21.4%), and chronic GVHD was observed and graded as limited in 24 patients (35.3%) and extensive in 8 (11.7%). Three-year overall survival (OS) was 61.8% (95% confidence interval [CI], 50.2% to 71.4%) and event-free survival (EFS) was 52.0% (95% CI, 40.3% to 62.4%). Age ≥15 years was associated with decreased OS (P= .05) and EFS (P= .05). Relapse was more common in children in second complete remission (P = .03). Partially CD3+-depleted alternative donor PSCT NRM, OS, and EFS compare favorably with previously published studies of T cell-replete PSCT. Historically, T cell-replete PSCT has been associated with a higher incidence of extensive chronic GVHD compared with limited chronic GVHD, which may explain the comparatively low relapse and NRM rates in our study cohort despite similar overall rates of chronic GVHD. Partial T cell depletion may expand donor options for children with malignant transplantation indications lacking a matched related donor by mitigating, but not eliminating, chronic GVHD.

Preclinical efficacy of daratumumab in T-cell acute lymphoblastic leukemia.

As a consequence of acquired or intrinsic disease resistance, the prognosis for patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL) is dismal. Novel, less toxic drugs are clearly needed. One of the most promising emerging therapeutic strategies for cancer treatment is targeted immunotherapy. Immune therapies have improved outcomes for patients with other hematologic malignancies including B-cell ALL; however no immune therapy has been successfully developed for T-ALL. We hypothesize targeting CD38 will be effective against T-ALL. We demonstrate that blasts from patients with T-ALL have robust surface CD38 surface expression and that this expression remains stable after exposure to multiagent chemotherapy. CD38 is expressed at very low levels on normal lymphoid and myeloid cells and on a few tissues of nonhematopoietic origin, suggesting that CD38 may be an ideal target. Daratumumab is a human immunoglobulin G1κ monoclonal antibody that binds CD38, and has been demonstrated to be safe and effective in patients with refractory multiple myeloma. We tested daratumumab in a large panel of T-ALL patient-derived xenografts (PDX) and found striking efficacy in 14 of 15 different PDX. These data suggest that daratumumab is a promising novel therapy for pediatric T-ALL patients.

Thoracic duct lymphatic fluid harbors phenotypically naive T cells for use in adoptive T-cell therapy.

BACKGROUND AIMS: Manufacturing of potent chimeric antigen receptor (CAR) T cells requires phenotypically naive and early memory T cells. We hypothesized lymphatic fluid collected from the thoracic duct of children would serve as a unique reservoir for early T cells, which could then be used for CAR T-cell therapy. METHODS: We evaluated lymphatic fluid collected from 25 pediatric patients undergoing thoracic duct cannulation for other clinical indications. RESULTS: Lymphatic fluid in the thoracic duct was rich in T cells, with higher percentage of naive and stem central memory T-cell subsets compared with paired blood samples. T cells from lymphatic fluid showed decreased negative checkpoint regulators on the surface and increased rapid expansion with bead activation. Creation of CD19-directed CAR T cells from blood and lymphatic T cells showed similar lentiviral transduction properties, but CAR T cells generated from lymphatic fluid produced superior cytotoxicity in a murine leukemia model because they were able to achieve equivalent tumor eradication at lower doses. CONCLUSIONS: These results are the first characterization of T cells from the thoracic duct of pediatric patients and suggest an alternative approach for manufacturing of cellular therapy that will improve both expansion and cytotoxic effect.

The Emerging Role of In Vitro-Transcribed mRNA in Adoptive T Cell Immunotherapy.

Adoptive T cell therapy is a form of cellular therapy that utilizes human immune cells, often empowered by the expression of recombinant proteins, to attack selected targets present on tumor or infected cells. T cell-based immunotherapy has been progressing over the past several decades, and reached a milestone with the recent US Food and Drug Administration (FDA) approval of chimeric antigen receptor T cell therapy for relapsed and refractory leukemia and lymphoma. Although most studies have used viral vectors, a growing number of researchers have come to appreciate in vitro-transcribed (IVT) mRNA for the development, testing, and application of T cell-based immunotherapeutics. IVT mRNA offers inherent safety features, highly efficient recombinant protein translation, and the ability to control pharmacokinetic properties of the therapy. In this review, we discuss the history of IVT mRNA in adoptive T cell therapy, from tumor-infiltrating lymphocytes and T cell receptor-based therapies to chimeric antigen receptor therapy and gene-editing techniques, as well as prior and ongoing clinical trials.

CD3+/CD19+ Depleted Matched and Mismatched Unrelated Donor Hematopoietic Stem Cell Transplant with Targeted T Cell Addback Is Associated with Excellent Outcomes in Pediatric Patients with Nonmalignant Hematologic Disorders.

Unrelated donor hematopoietic stem cell transplantation (HSCT) is increasingly being used to cure nonmalignant hematologic diseases (NMHD) in patients who lack HLA matched related donors. Both graft rejection and graft-versus-host disease (GVHD) remain major barriers to safe and effective transplant for these patients requiring unrelated donors. Partial T cell depletion combined with peripheral stem cell transplantation (pTCD-PSCT) has the potential advantages of providing a high stem cell dose to facilitate rapid engraftment, maintaining cells that may facilitate engraftment, and decreasing GVHD risk compared with T cell-replete HSCT. Here, we report a single-institution, retrospective experience of unrelated donor pTCD-PSCT for pediatric patients with NMHD. From 2014 to 2017, 12 pediatric patients with transfusion-dependent NMHD underwent matched unrelated donor (MUD) or mismatched unrelated donor (MMUD) pTCD HSCT in our center using disease-specific conditioning. Donor PSCs underwent CD3+ T cell and CD19+ B cell depletion using CliniMACS, followed by a targeted addback of 1 × 105 CD3+ T cells/kg to the graft before infusion. All 12 patients demonstrated rapid trilinear engraftment. At a median follow-up of 740days (range, 279 to 1466), all patients were alive with over 92% total peripheral blood donor chimerism and without transfusion dependence or recurrence of their underlying hematologic disease. Immune reconstitution was rapid and comparable with T cell-replete HSCT. No patients developed severe acute GVHD (grades III to IV) or chronic extensive GVHD, and all patients had discontinued systemic immune suppression. Viral reactivations were common, but no patient developed symptoms of life-threatening infectious disease. Our data indicate that MUD and MMUD pTCD-PSCTs are safe and effective approaches that enable rapid engraftment and immune reconstitution, prevent severe GVHD, and expand availability of HSCT to any patients with NMHD who have closely MUDs.

Neurotoxicity after CTL019 in a pediatric and young adult cohort.

OBJECTIVE: To characterize the incidence and clinical characteristics of neurotoxicity in the month following CTL019 infusion in children and young adults, to define the relationship between neurotoxicity and cytokine release syndrome (CRS), and to identify predictive biomarkers for development of neurotoxicity following CTL019 infusion. METHODS: We analyzed data on 51 subjects, 4 to 22 years old, who received CTL019, a chimeric antigen receptor-modified T-cell therapy against CD19, between January 1, 2010 and December 1, 2015 through a safety/feasibility clinical trial (NCT01626495) at our institution. We recorded incidence of significant neurotoxicity (encephalopathy, seizures, and focal deficits) and CRS, and compared serum cytokine levels in the first month postinfusion between subjects who did and did not develop neurotoxicity. RESULTS: Neurotoxicity occurred in 23 of 51 subjects (45%, 95% confidence interval = 31-60%) and was positively associated with higher CRS grade (p < 0.0001) but was not associated with demographic characteristics or prior oncologic treatment history. Serum interleukin (IL)-2, IL-15, soluble IL-4, and hepatocyte growth factor concentrations were higher in subjects with neurotoxicity than those with isolated CRS. Differences in peak levels of select cytokines including IL-12 and soluble tumor necrosis factor receptor-1 within the first 3 days were seen in subjects with neurotoxicity. INTERPRETATION: Neurotoxicity is common after CTL019 infusion in children and young adults, and is associated with higher CRS grade. Differences in serum cytokine profiles between subjects with neurotoxicity and those with isolated CRS suggest unique pathophysiological mechanisms. Serum cytokine profiles in the first 3 days postinfusion may help identify children and young adults at risk for neurotoxicity, and may provide a foundation for investigation into potential mitigation strategies. Ann Neurol 2018;84:537-546.

Ibrutinib enhances chimeric antigen receptor T-cell engraftment and efficacy in leukemia.

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy is highly promising but requires robust T-cell expansion and engraftment. A T-cell defect in chronic lymphocytic leukemia (CLL) due to disease and/or therapy impairs ex vivo expansion and response to CAR T cells. To evaluate the effect of ibrutinib treatment on the T-cell compartment in CLL as it relates to CAR T-cell generation, we examined the phenotype and function of T cells in a cohort of CLL patients during their course of treatment with ibrutinib. We found that ≥5 cycles of ibrutinib therapy improved the expansion of CD19-directed CAR T cells (CTL019), in association with decreased expression of the immunosuppressive molecule programmed cell death 1 on T cells and of CD200 on B-CLL cells. In support of these findings, we observed that 3 CLL patients who had been treated with ibrutinib for ≥1 year at the time of T-cell collection had improved ex vivo and in vivo CTL019 expansion, which correlated positively together and with clinical response. Lastly, we show that ibrutinib exposure does not impair CAR T-cell function in vitro but does improve CAR T-cell engraftment, tumor clearance, and survival in human xenograft models of resistant acute lymphocytic leukemia and CLL when administered concurrently. Our collective findings indicate that ibrutinib enhances CAR T-cell function and suggest that clinical trials with combination therapy are warranted. Our studies demonstrate that improved T-cell function may also contribute to the efficacy of ibrutinib in CLL. These trials were registered at www.clinicaltrials.gov as #NCT01747486, #NCT01105247, and #NCT01217749.

Chimeric antigen receptor T cells for sustained remissions in leukemia.

BACKGROUND: Relapsed acute lymphoblastic leukemia (ALL) is difficult to treat despite the availability of aggressive therapies. Chimeric antigen receptor-modified T cells targeting CD19 may overcome many limitations of conventional therapies and induce remission in patients with refractory disease. METHODS: We infused autologous T cells transduced with a CD19-directed chimeric antigen receptor (CTL019) lentiviral vector in patients with relapsed or refractory ALL at doses of 0.76×10(6) to 20.6×10(6) CTL019 cells per kilogram of body weight. Patients were monitored for a response, toxic effects, and the expansion and persistence of circulating CTL019 T cells. RESULTS: A total of 30 children and adults received CTL019. Complete remission was achieved in 27 patients (90%), including 2 patients with blinatumomab-refractory disease and 15 who had undergone stem-cell transplantation. CTL019 cells proliferated in vivo and were detectable in the blood, bone marrow, and cerebrospinal fluid of patients who had a response. Sustained remission was achieved with a 6-month event-free survival rate of 67% (95% confidence interval [CI], 51 to 88) and an overall survival rate of 78% (95% CI, 65 to 95). At 6 months, the probability that a patient would have persistence of CTL019 was 68% (95% CI, 50 to 92) and the probability that a patient would have relapse-free B-cell aplasia was 73% (95% CI, 57 to 94). All the patients had the cytokine-release syndrome. Severe cytokine-release syndrome, which developed in 27% of the patients, was associated with a higher disease burden before infusion and was effectively treated with the anti-interleukin-6 receptor antibody tocilizumab. CONCLUSIONS: Chimeric antigen receptor-modified T-cell therapy against CD19 was effective in treating relapsed and refractory ALL. CTL019 was associated with a high remission rate, even among patients for whom stem-cell transplantation had failed, and durable remissions up to 24 months were observed. (Funded by Novartis and others; CART19 ClinicalTrials.gov numbers, NCT01626495 and NCT01029366.).

Cytokine Release Syndrome After Chimeric Antigen Receptor T Cell Therapy for Acute Lymphoblastic Leukemia.

OBJECTIVE: Initial success with chimeric antigen receptor-modified T cell therapy for relapsed/refractory acute lymphoblastic leukemia is leading to expanded use through multicenter trials. Cytokine release syndrome, the most severe toxicity, presents a novel critical illness syndrome with limited data regarding diagnosis, prognosis, and therapy. We sought to characterize the timing, severity, and intensive care management of cytokine release syndrome after chimeric antigen receptor-modified T cell therapy. DESIGN: Retrospective cohort study. SETTING: Academic children's hospital. PATIENTS: Thirty-nine subjects with relapsed/refractory acute lymphoblastic leukemia treated with chimeric antigen receptor-modified T cell therapy on a phase I/IIa clinical trial (ClinicalTrials.gov number NCT01626495). INTERVENTIONS: All subjects received chimeric antigen receptor-modified T cell therapy. Thirteen subjects with cardiovascular dysfunction were treated with the interleukin-6 receptor antibody tocilizumab. MEASUREMENTS AND MAIN RESULTS: Eighteen subjects (46%) developed grade 3-4 cytokine release syndrome, with prolonged fever (median, 6.5 d), hyperferritinemia (median peak ferritin, 60,214 ng/mL), and organ dysfunction. Fourteen (36%) developed cardiovascular dysfunction treated with vasoactive infusions a median of 5 days after T cell therapy. Six (15%) developed acute respiratory failure treated with invasive mechanical ventilation a median of 6 days after T cell therapy; five met criteria for acute respiratory distress syndrome. Encephalopathy, hepatic, and renal dysfunction manifested later than cardiovascular and respiratory dysfunction. Subjects had a median of 15 organ dysfunction days (interquartile range, 8-20). Treatment with tocilizumab in 13 subjects resulted in rapid defervescence (median, 4 hr) and clinical improvement. CONCLUSIONS: Grade 3-4 cytokine release syndrome occurred in 46% of patients following T cell therapy for relapsed/refractory acute lymphoblastic leukemia. Clinicians should be aware of expanding use of this breakthrough therapy and implications for critical care units in cancer centers.

Eradication of B-ALL using chimeric antigen receptor-expressing T cells targeting the TSLPR oncoprotein.

Adoptive transfer of T cells genetically modified to express chimeric antigen receptors (CARs) targeting the CD19 B cell-associated protein have demonstrated potent activity against relapsed/refractory B-lineage acute lymphoblastic leukemia (B-ALL). Not all patients respond, and CD19-negative relapses have been observed. Overexpression of the thymic stromal lymphopoietin receptor (TSLPR; encoded by CRLF2) occurs in a subset of adults and children with B-ALL and confers a high risk of relapse. Recent data suggest the TSLPR signaling axis is functionally important, suggesting that TSLPR would be an ideal immunotherapeutic target. We constructed short and long CARs targeting TSLPR and tested efficacy against CRLF2-overexpressing B-ALL. Both CARs demonstrated activity in vitro, but only short TSLPR CAR T cells mediated leukemia regression. In vivo activity of the short CAR was also associated with long-term persistence of CAR-expressing T cells. Short TSLPR CAR treatment of mice engrafted with a TSLPR-expressing ALL cell line induced leukemia cytotoxicity with efficacy comparable with that of CD19 CAR T cells. Short TSLPR CAR T cells also eradicated leukemia in 4 xenograft models of human CRLF2-overexpressing ALL. Finally, TSLPR has limited surface expression on normal tissues. TSLPR-targeted CAR T cells thus represent a potent oncoprotein-targeted immunotherapy for high-risk ALL.

Monocyte lineage-derived IL-6 does not affect chimeric antigen receptor T-cell function.

BACKGROUND AIMS: Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 has demonstrated remarkable success in targeting B-cell malignancies but is often complicated by serious systemic toxicity in the form of cytokine release syndrome (CRS). CRS symptoms are primarily mediated by interleukin 6 (IL-6), and clinical management has focused on inhibition of IL-6 signaling. The cellular source and function of IL-6 in CRS remain unknown. METHODS: Using co-culture assays and data from patients on our clinical CAR T-cell trials, we investigated the cellular source of IL-6, as well as other CRS-associated cytokines, during CAR T-cell activation. We also explored the effect that IL-6 has on T-cell function. RESULTS: We demonstrated that IL-6 is secreted by monocyte-lineage cells in response to CAR T-cell activation in a contact-independent mechanism upon T-cell engagement of target leukemia. We observed that the presence of antigen-presenting cell-derived IL-6 has no impact on CAR T-cell transcriptional profiles or cytotoxicity. Finally, we confirm that CAR T cells do not secrete IL-6 in vivo during clinical CRS. DISCUSSION: These findings suggest that IL-6 blockade will not affect CD19 CAR T-cell-driven anti-leukemic cytotoxicity, permitting enhanced control of CRS while maintaining CAR T-cell efficacy.

Chimeric Antigen Receptor- and TCR-Modified T Cells Enter Main Street and Wall Street.

The field of adoptive cell transfer (ACT) is currently comprised of chimeric Ag receptor (CAR)- and TCR-engineered T cells and has emerged from principles of basic immunology to paradigm-shifting clinical immunotherapy. ACT of T cells engineered to express artificial receptors that target cells of choice is an exciting new approach for cancer, and it holds equal promise for chronic infection and autoimmunity. Using principles of synthetic biology, advances in immunology, and genetic engineering have made it possible to generate human T cells that display desired specificities and enhanced functionalities. Clinical trials in patients with advanced B cell leukemias and lymphomas treated with CD19-specific CAR T cells have induced durable remissions in adults and children. The prospects for the widespread availability of engineered T cells have changed dramatically given the recent entry of the pharmaceutical industry to this arena. In this overview, we discuss some of the challenges and opportunities that face the field of ACT.

Chimeric antigen receptor therapy for cancer.

Improved outcomes for patients with cancer hinge on the development of new targeted therapies with acceptable short-term and long-term toxicity. Progress in basic, preclinical, and clinical arenas spanning cellular immunology, synthetic biology, and cell-processing technologies has paved the way for clinical applications of chimeric antigen receptor-based therapies. This new form of targeted immunotherapy merges the exquisite targeting specificity of monoclonal antibodies with the potent cytotoxicity and long-term persistence provided by cytotoxic T cells. Although this field is still in its infancy, clinical trials have already shown clinically significant antitumor activity in neuroblastoma, chronic lymphocytic leukemia, and B cell lymphoma, and trials targeting a variety of other adult and pediatric malignancies are under way. Ongoing work is focused on identifying optimal tumor targets and on elucidating and manipulating both cell- and host-associated factors to support expansion and persistence of the genetically engineered cells in vivo. The potential to target essentially any tumor-associated cell-surface antigen for which a monoclonal antibody can be made opens up an entirely new arena for targeted therapy of cancer.

Current status of chimeric antigen receptor therapy for haematological malignancies.

The field of adoptive cell transfer includes chimeric antigen receptor (CAR) engineered T cells, constructs that emerged from basic research into principles of immunology and have transformed into clinically effective therapies for haematological malignancies. T cells engineered to express these artificial receptors hold great promise, but also carry significant risk. While permanent genetic modification of mature T cells appears safe, modulating their in vivo function is difficult, partly because the robust response can trigger other arms of the immune system. Suicide systems and toxicity management with cytokine blockade or signal transduction modulators have emerged as a new frontier in this field, a far cry from early problems getting CAR T cells to work at all. Currently, clinical trials in patients with relapsed or refractory B cell malignancies treated with CD19-specific CAR T cells have induced durable remissions in adults and children. Results from these trials indicate that more work needs to be done to understand biomarkers of efficacy, the role of T cell persistence and how to integrate this care into standard practice. Cell therapy will not be a 'one size fits all' class of medicine, and here we will discuss the development of this therapy and important questions for its future.