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Abstract: Immune effector cell-associated neurotoxicity syndrome (ICANS) is a common but potentially severe adverse event associated with chimeric antigen receptor T-cell (CART) therapy, characterized by the development of acute neurologic symptoms following CART infusion. ICANS encompasses a wide clinical spectrum typified by mild to severe encephalopathy, seizures, and/or cerebral edema. As more patients have been treated with CART, new ICANS phenomenology has emerged. We present the clinical course of 5 children who developed acute onset of quadriparesis or paraparesis associated with abnormal brain and/or spine neuroimaging after infusion of CD19- or CD22-directed CART, adverse events not previously reported in children. Orthogonal data from autopsy studies, cerebrospinal fluid (CSF) flow cytometry, and CSF proteomics/cytokine profiling demonstrated chronic white matter destruction, but a notable lack of inflammatory pathologic changes and cell populations. Instead, children with quadriparesis or paraparesis post-CART therapy had lower levels of proinflammatory cytokines, such as interferon gamma, CCL17, CCL23, and CXCL10, than those who did not develop quadriparesis or paraparesis. Taken together, these findings imply a noninflammatory source of this newly described ICANS phenomenon in children. The pathophysiology of some neurologic symptoms following CART may therefore have a more complex etiology than exclusive T-cell activation and excessive cytokine production., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Abstract: Relapse after CD19-directed chimeric antigen receptor (CAR)-modified T cells remains a substantial challenge. Short CAR T-cell persistence contributes to relapse risk, necessitating novel approaches to prolong durability. CAR T-cell reinfusion (CARTr) represents a potential strategy to reduce the risk of or treat relapsed disease after initial CAR T-cell infusion (CARTi). We conducted a retrospective review of reinfusion of murine (CTL019) or humanized (huCART19) anti-CD19/4-1BB CAR T cells across 3 clinical trials or commercial tisagenlecleucel for relapse prevention (peripheral B-cell recovery [BCR] or marrow hematogones ≤6 months after CARTi), minimal residual disease (MRD) or relapse, or nonresponse to CARTi. The primary endpoint was complete response (CR) at day 28 after CARTr, defined as complete remission with B-cell aplasia. Of 262 primary treatments, 81 were followed by ≥1 reinfusion (investigational CTL019, n = 44; huCART19, n = 26; tisagenlecleucel, n = 11), representing 79 patients. Of 63 reinfusions for relapse prevention, 52% achieved CR (BCR, 15/40 [38%]; hematogones, 18/23 [78%]). Lymphodepletion was associated with response to CARTr for BCR (odds ratio [OR], 33.57; P = .015) but not hematogones (OR, 0.30; P = .291). The cumulative incidence of relapse was 29% at 24 months for CR vs 61% for nonresponse to CARTr (P = .259). For MRD/relapse, CR rate to CARTr was 50% (5/10), but 0/8 for nonresponse to CARTi. Toxicity was generally mild, with the only grade ≥3 cytokine release syndrome (n = 6) or neurotoxicity (n = 1) observed in MRD/relapse treatment. Reinfusion of CTL019/tisagenlecleucel or huCART19 is safe, may reduce relapse risk in a subset of patients, and can reinduce remission in CD19+ relapse., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

The approval of tisagenlecleucel (tisa-cel) for use in children with B cell acute lymphoblastic leukemia (B-ALL) was based on the phase 2 ELIANA trial, a global registration study. However, the ELIANA trial excluded specific subsets of patients facing unique challenges and did not include a sufficient number of patients to adequately evaluate outcomes in rare subpopulations. Since the commercialization of tisa-cel, data have become available that support therapeutic indications beyond the specific cohorts previously eligible for chimeric antigen receptor (CAR) T cells targeted to CD19 (CD19 CAR-T) therapy on the registration clinical trial. Substantial real-world data and aggregate clinical trial data have addressed gaps in our understanding of response rates, longer-term efficacy, and toxicities associated with CD19 CAR-T in special populations and rare clinical scenarios. These include patients with central nervous system relapsed disease, who were excluded from ELIANA and other early CAR-T trials owing to concerns about risk of neurotoxicity that have not been born out. There is also interest in the use of CD19 CAR-T for very-high-risk patients earlier in the course of therapy, such as patients with persistent minimal residual disease after 2 cycles of upfront chemotherapy and patients with first relapse of B-ALL. However, these indications are not specified on the label for tisa-cel and historically were not included in eligibility criteria for most clinical trials; data addressing these populations are needed. Populations at high risk of relapse, including patients with high-risk cytogenetic lesions, infants with B-ALL, patients with trisomy 21, and young adults with B-ALL, also may benefit from earlier treatment with CD19 CAR-T. It is important to prospectively study patient-reported outcomes given the differential toxicity expected between CD19 CAR-T and the historic standard of care, hematopoietic cell transplantation. Now that CD19 CAR-T therapy is commercially available, studies evaluating potential access disparities created by this very expensive novel therapy are increasingly pressing., (Copyright © 2023 The American Society for Transplantation and Cellular Therapy. All rights reserved.)

Over the past decade, CAR T cell therapy has transformed the treatment of relapsed or refractory B-ALL in children and adults. CD19-directed CAR T cells can induce complete remissions in a large majority of patients with B-ALL, and up to half of these patients will go on to maintain durable remissions. However, significant challenges remain for patients who relapse or do not respond. This review will discuss the history of CAR T cell therapy for B-ALL, the treatment considerations for CAR T cell recipients, and current clinical trials and future directions for CAR T cell therapy in B-ALL., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Although CD19-directed chimeric antigen receptor (CAR) T cell therapy (CAR-T) for relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) has been transformative in inducing and sustaining remission, relapse rates remain unacceptably high, with approximately 50% of children and young adults experiencing relapse within the first year postinfusion. Emerging strategies to extend the durability of remission involve the use of prognostic biomarkers to identify those at high risk of relapse or incorporate strategies aimed to enhancing functional CAR T cell persistence. Nonetheless, with antigen loss/down-regulation or evolution to lineage switch as major mechanisms of relapse, optimizing single antigen targeting alone is insufficient. Here, with a focus on relapse prevention strategies, including postinfusion surveillance and treatment approaches being explored to optimize post-CAR-T management (eg, combinatorial antigen targeting strategies, preemptive hematopoietic cell transplantation), we review the current state of the art in the prevention and management of post CAR-T relapse. We highlight the advancements in the field and identify gaps in the literature to guide future research in optimizing the prevention and management of post-CAR-T relapse in children and young adults with B-ALL., (Copyright © 2023. Published by Elsevier Inc.)

Outcomes for post-chimeric antigen receptor (CAR) T cell therapy (CART) relapse are poor. The utilization of a unique CAR T cell construct for post-CART failure is increasing, but this approach is not well described. In this study, with CART-A the first unique CAR T cell construct received and CART-B the second, the primary objective was to characterize outcomes following CART-B. Secondary objectives included evaluating safety and toxicity with sequential CART infusions; investigating the impact of potential factors, such as antigen modulation and interval therapy, on CART-B response; and characterizing long-term outcomes in patients receiving multiple CARTs. This was a retrospective review (NCT03827343) of children and young adults with B cell acute lymphoblastic leukemia (B-ALL) undergoing CART therapy who received at least 2 unique CART constructs, excluding interim CART reinfusions of the same product. Of 135 patients, 61 (45.1%) received 2 unique CART constructs, including 13 who received >2 CARTs over time. Patients included in this analysis received 14 distinct CARTs targeting CD19 and/or CD22. The median age at CART-A was 12.6 years (range, 3.3 to 30.4 years). The median time from CART-A to CART-B was 302 days (range, 53 to 1183 days). CART-B targeted a different antigen than CART-A in 48 patients (78.7%), owing primarily to loss of CART-A antigen target. The rate of complete remission (CR) was lower with CART-B (65.5%; 40 of 61) than with CART-A (88.5%; 54 of 61; P = .0043); 35 of 40 (87.5%) CART-B responders had CART-B targeting a different antigen than CART-A. Among the 21 patients with a partial response or nonresponse to CART-B, 8 (38.1%) received CART-B with the same antigen target as CART-A. Of 40 patients with CART-B complete response (CR), 29 (72.5%) relapsed. For the 21 patients with evaluable data, the relapse immunophenotype was antigen negative in 3 (14.3%), antigen dim in 7 (33.3%), antigen positive in 10 (47.6%), and lineage switch in 1 (4.8%). The median relapse-free survival following CART-B CR was 9.4 months (95% confidence interval [CI], 6.1 to 13.2 months), and overall survival was 15.0 months (95% CI, 13.0 to 22.7 months). Given the limited salvage options for post-CART relapse, identifying optimizing strategies for CART-B is critical. We raise awareness about the emerging use of CART for post-CART failure and highlight clinical implications accompanying this paradigm shift., (Published by Elsevier Inc.)

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. In the primary analysis of the global phase II ELIANA trial (ClinicalTrials.gov identifier: NCT02435849), tisagenlecleucel provided an overall remission rate of 81% in pediatric and young adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), with 59% of responders remaining relapse-free at 12 months. Here, we report an update on efficacy, safety, and patient-reported quality of life in 79 pediatric and young adult patients with R/R B-ALL following a median follow-up of 38.8 months. The overall remission rate was 82%. The median event-free survival was 24 months, and the median overall survival was not reached. Event-free survival was 44% (95% CI, 31 to 57) and overall survival was 63% (95% CI, 51 to 73) at 3 years overall (most events occur within the first 2 years). The estimated 3-year relapse-free survival with and without censoring for subsequent therapy was 52% (95% CI, 37 to 66) and 48% (95% CI, 34 to 60), respectively. No new or unexpected long-term adverse events were reported. Grade 3/4 adverse events were reported in 29% of patients > 1 year after infusion; grade 3/4 infection rate did not increase > 1 year after infusion. Patients reported improvements in quality of life up to 36 months after infusion. These findings demonstrate favorable long-term safety and suggest tisagenlecleucel as a curative treatment option for heavily pretreated pediatric and young adult patients with R/R B-ALL., Competing Interests: Theodore W. LaetschStock and Other Ownership Interests: Advanced MicrobubblesConsulting or Advisory Role: Novartis, Bayer, Cellectis, Aptitude Health, Clinical Education Alliance, Deciphera, Jumo Health, Massive Bio, Med Learning Group, Medscape, Physicans' Education Resource, Y-mAbs Therapeutics, AI Therapeutics, Jazz Pharmaceuticals, GentiBio, Menarini, Pyramid BiosciencesResearch Funding: Pfizer (Inst), Novartis (Inst), Bayer (Inst), AbbVie (Inst), Amgen (Inst), Atara Biotherapeutics (Inst), Bristol Myers Squibb (Inst), Lilly (Inst), Epizyme (Inst), GlaxoSmithKline (Inst), Janssen (Inst), Jubilant Pharmaceuticals (Inst), Novella Clinical (Inst), Servier (Inst), Foundation Medicine (Inst), Merck Sharp & Dohme (Inst), Turning Point Therapeutics (Inst) Shannon L. MaudeConsulting or Advisory Role: Novartis, KiteResearch Funding: Novartis (Inst), Wugen, Inc (Inst)Patents, Royalties, Other Intellectual Property: PCT/US2017/044425: Combination Therapies of Car and PD-1 InhibitorsTravel, Accommodations, Expenses: Novartis Susana RivesHonoraria: Novartis, Kite/Gilead, Celgene/Bristol Myers Squibb, Shire/ServierConsulting or Advisory Role: Servier, Amgen, Novartis, Kite/Gilead, Shire/Servier, Celgene/Bristol Myers Squibb, Cellectis, Jazz PharmaceuticalsSpeakers' Bureau: NovartisResearch Funding: Novartis (Inst)Travel, Accommodations, Expenses: Novartis, Shire/Servier, Cellectis, Jazz Pharmaceuticals Hidefumi HiramatsuHonoraria: Novar PharmaConsulting or Advisory Role: Novartis Henrique BittencourtConsulting or Advisory Role: Novartis Canada Pharmaceuticals Inc, Jazz PharmaceuticalsSpeakers' Bureau: Novartis Oncology Canada Peter BaderHonoraria: Medac (Inst), Riemser (Inst), Neovii (Inst)Consulting or Advisory Role: Novartis (Inst), Amgen (Inst), Miltenyi (Inst), Servier (Inst)Speakers' Bureau: Novartis (Inst), Amgen (Inst), Riemser (Inst), Medac (Inst), Miltenyi (Inst), Servier (Inst)Research Funding: Medac (Inst), Neovii (Inst), Riemser (Inst)Patents, Royalties, Other Intellectual Property: Patent on MSC licensend to Medac André BaruchelLeadership: DBV Technologies, lysogen, Medday Pharmaceuticals, Ascendis PharmaStock and Other Ownership Interests: DBV Technologies, Ascendis PharmaHonoraria: Novartis, Kite, a Gilead company, AstraZenecaConsulting or Advisory Role: Jazz Pharmaceuticals, Novartis, Servier, CelgeneResearch Funding: Jazz Pharmaceuticals (Inst), Servier (Inst)Travel, Accommodations, Expenses: Jazz Pharmaceuticals, Sanofi, Servier Michael BoyerHonoraria: NovartisEmployment: Thunder BiotechLeadership: Thunder Biotech Barbara De MoerlooseConsulting or Advisory Role: NovartisUncompensated Relationships: Novartis (Inst), Gilead Sciences (Inst), Articulate Science, Jazz Pharmaceuticals Muna QayedHonoraria: Novartis, Vertex, Medexus, Jazz Pharmaceuticals, MesoblastConsulting or Advisory Role: NovartisTravel, Accommodations, Expenses: Novartis Jochen BuechnerHonoraria: Novartis, Pfizer, KiteConsulting or Advisory Role: Novartis, Janssen (Inst), Amgen (Inst)Speakers' Bureau: Novartis Michael A. PulsipherThis author is a member of the Journal of Clinical Oncology Editorial Board. Journal policy recused the author from having any role in the peer review of this manuscript.Honoraria: Novartis, MesoblastConsulting or Advisory Role: Novartis, Medexus Pharmaceuticals, Equillium, Gentibio, Vertex, Bluebird BioResearch Funding: Adaptive Biotechnologies, Miltenyi Biotec Gary Douglas MyersHonoraria: NovartisConsulting or Advisory Role: NovartisSpeakers' Bureau: NovartisResearch Funding: Novartis (Inst) Heather E. StefanskiConsulting or Advisory Role: NovartisSpeakers' Bureau: Novartis Paul L. MartinConsulting or Advisory Role: Neovii Biotech GmbH, Genentech, Enlivex Therapeutics, and PharmacyclicsResearch Funding: Novartis (Inst), Bluebird Bio (Inst), AbGenomics (Inst) Eneida NemecekConsulting or Advisory Role: Novartis, Medexus, Atara Bio Christina PetersHonoraria: Neovii, Jazz Pharmaceuticals, NovartisConsulting or Advisory Role: Amgen, Neovii, NovartisSpeakers' Bureau: Medac, Riemser, AmgenResearch Funding: Medac (Inst), Neovii (Inst), Riemser (Inst), Jazz Pharmaceuticals (Inst), Amgen (Inst)Travel, Accommodations, Expenses: Neovii, Jazz Pharmaceuticals, Novartis Seong Lin KhawHonoraria: Novartis Kara L. DavisHonoraria: NovartisResearch Funding: Jazz Pharmaceuticals Joerg KruegerEmployment: JanssenConsulting or Advisory Role: Novartis, Kite/Gilead, SOBIOther Relationship: Canadian Agency for Drugs and Technologies in Health (CADTH) Adriana BalduzziSpeakers' Bureau: Novartis, Amgen, MedacTravel, Accommodations, Expenses: Novartis, Medac, Neovii Nicolas BoisselHonoraria: Amgen, ARIAD/Incyte, Novartis, Servier, Astellas Pharma, Bristol Myers Squibb, Jazz Pharmaceuticals, Celgene, Sanofi, PfizerConsulting or Advisory Role: Amgen, Novartis, Servier, PfizerResearch Funding: Amgen, Novartis, Bristol Myers Squibb, Jazz PharmaceuticalsExpert Testimony: Amgen Ranjan TiwariEmployment: Novartis Darragh O’DonovanEmployment: Novartis Ireland LtdStock and Other Ownership Interests: Novartis Stephan A. GruppHonoraria: TCR2 Therapeutics, Eureka Therapeutics, CellectisConsulting or Advisory Role: Novartis, Jazz Pharmaceuticals, Janssen, Cellular Biomedicine Group, Roche, Adaptimmune, Alimera Sciences, Cabaletta Bio, CRISPR Therapeutics/VertexResearch Funding: Novartis (Inst), Kite/Gilead (Inst), Servier (Inst), Jazz Pharmaceuticals (Inst), Vertex (Inst)Patents, Royalties, Other Intellectual Property: UPenn Toxicity management patent (Inst)Expert Testimony: Juno TherapeuticsNo other potential conflicts of interest were reported.

Children living in poverty experience excessive relapse and death from newly diagnosed acute lymphoblastic leukemia (ALL). The influence of household poverty and neighborhood social determinants on outcomes from chimeric antigen receptor (CAR) T-cell therapy for relapsed/refractory (r/r) leukemia is poorly described. We identified patients with r/r CD19+ ALL/lymphoblastic lymphoma treated on CD19-directed CAR T-cell clinical trials or with commercial tisagenlecleucel from 2012 to 2020. Socioeconomic status (SES) was proxied at the household level, with poverty exposure defined as Medicaid-only insurance. Low-neighborhood opportunity was defined by the Childhood Opportunity Index. Among 206 patients aged 1 to 29, 35.9% were exposed to household poverty, and 24.9% had low-neighborhood opportunity. Patients unexposed to household poverty or low-opportunity neighborhoods were more likely to receive CAR T-cell therapy with a high disease burden (>25%), a disease characteristic associated with inferior outcomes, as compared with less advantaged patients (38% vs 30%; 37% vs 26%). Complete remission (CR) rate was 93%, with no significant differences by household poverty (P = .334) or neighborhood opportunity (P = .504). In multivariate analysis, patients from low-opportunity neighborhoods experienced an increased hazard of relapse as compared with others (P = .006; adjusted hazard ratio [HR], 2.3; 95% confidence interval [CI], 1.3-4.1). There was no difference in hazard of death (P = .545; adjusted HR, 1.2; 95% CI, 0.6-2.4). Among children who successfully receive CAR T-cell therapy, CR and overall survival are equitable regardless of proxied SES and neighborhood opportunity. Children from more advantaged households and neighborhoods receive CAR T-cell therapy with a higher disease burden. Investigation of multicenter outcomes and access disparities outside of clinical trial settings is warranted., (© 2023 by The American Society of Hematology.)

Background: Immunocompromised patients are at increased risk of SARS-CoV-2 infections. Patients undergoing chimeric antigen receptor (CAR) T-cell therapy for relapsed/refractory B-cell malignancies are uniquely immunosuppressed due to CAR T-mediated B-cell aplasia (BCA). While SARS-CoV-2 mortality rates of 33%-40% are reported in adult CAR T-cell recipients, outcomes in pediatric and young adult CAR T-cell recipients are limited., Methods: We created an international retrospective registry of CAR T recipients aged 0-30 years infected with SARS-CoV-2 within 2 months prior to or any time after CAR T infusion. SARS-CoV-2-associated illness was graded as asymptomatic, mild, moderate, or severe COVID-19, or multisystem inflammatory syndrome in children (MIS-C). To assess for risk factors associated with significant SARS-CoV-2 infections (infections requiring hospital admission for respiratory distress or supplemental oxygen), univariate and multivariable regression analyses were performed., Results: Nine centers contributed 78 infections in 75 patients. Of 70 SARS-CoV-2 infections occurring after CAR T infusion, 13 (18.6%) were classified as asymptomatic, 37 (52.9%) mild, 11 (15.7%) moderate, and 6 (8.6%) severe COVID-19. Three (4.3%) were classified as MIS-C. BCA was not significantly associated with infection severity. Prior to the emergence of the Omicron variant, of 47 infections, 19 (40.4%) resulted in hospital admission and 7 (14.9%) required intensive care, while after the emergence of the Omicron variant, of 23 infections, only 1 (4.3%) required admission and the remaining 22 (95.7%) had asymptomatic or mild COVID-19. Death occurred in 3 of 70 (4.3%); each death involved coinfection or life-threatening condition. In a multivariable model, factors associated with significant SARS-CoV-2 infection included having two or more comorbidities (OR 7.73, CI 1.05 to 74.8, p=0.048) and age ≥18 years (OR 9.51, CI 1.90 to 82.2, p=0.014). In the eight patients infected with SARS-CoV-2 before CAR T, half of these patients had their CAR T infusion delayed by 15-30 days., Conclusions: In a large international cohort of pediatric and young adult CAR-T recipients, SARS-CoV-2 infections resulted in frequent hospital and intensive care unit admissions and were associated with mortality in 4.3%. Patients with two or more comorbidities or aged ≥18 years were more likely to experience significant illness. Suspected Omicron infections were associated with milder disease., Competing Interests: Competing interests: AB: Novartis, Amgen and Medac, speaker’s bureau; Medac, Neovii and Novartis meeting support. SLM: Novartis, advisory boards, study steering committees, clinical trial support; Wugen: advisory board., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Chimeric antigen receptor T-cell (CAR-T) therapy is an exciting development in the field of cancer immunology and has received a lot of interest in recent years. Many time-to-event (TTE) endpoints related to relapse, disease progression, and remission are analyzed in CAR-T studies to assess treatment efficacy. Definitions of these TTE endpoints are not always consistent, even for the same outcomes (e.g., progression-free survival), which often stems from analysis choices regarding which events to consider as part of the composite endpoint, censoring or competing risk in the analysis. Subsequent therapies such as hematopoietic stem cell transplantation are common but are not treated the same in different studies. Standard survival analysis methods are commonly applied to TTE analyses but often without full consideration of the assumptions inherent in the chosen analysis. We highlight two important issues of TTE analysis that arise in CAR-T studies, as well as in other settings in oncology: the handling of competing risks and assessing the association between a time-varying (post-infusion) exposure and the TTE outcome. We review existing analytical methods, including the cumulative incidence function and regression models for analysis of competing risks, and landmark and time-varying covariate analysis for analysis of post-infusion exposures. We clarify the scientific questions that the different analytical approaches address and illustrate how the application of an inappropriate method could lead to different results using data from multiple published CAR-T studies. Codes for implementing these methods in standard statistical software are provided., (©2022 The Authors; Published by the American Association for Cancer Research.)

Purpose: To study the biology and identify markers of severe cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) in children after chimeric antigen receptor T-cell (CAR T) treatment., Experimental Design: We used comprehensive proteomic profiling to measure over 1,400 serum proteins at multiple serial timepoints in a cohort of patients with B-cell acute lymphoblastic leukemia treated with the CD19-targeted CAR T CTL019 on two clinical trials., Results: We identified fms-like tyrosine kinase 3 (FLT3) and mast cell immunoglobulin-like receptor 1 (MILR1) as preinfusion predictive biomarkers of severe CRS. We demonstrated that CRS is an IFNγ-driven process with a protein signature overlapping with hemophagocytic lymphohistiocytosis (HLH). We identified IL18 as a potentially targetable cytokine associated with the development of ICANS., Conclusions: We identified preinfusion biomarkers that can be used to predict severe CRS with a sensitivity, specificity, and accuracy superior to the current gold standard of disease burden. We demonstrated the fundamental role of the IFNγ pathway in driving CRS, suggesting CRS and carHLH are overlapping rather than distinct phenomena, an observation with important treatment implications. We identified IL18 as a possible targetable cytokine in ICANS, providing rationale for IL18 blocking therapies to be translated into clinical trials in ICANS., (©2022 American Association for Cancer Research.)

Chimeric antigen receptor (CAR) T cells have emerged as a potent therapeutic approach for patients with certain haematological cancers, with multiple CAR T cell products currently approved by the FDA for those with relapsed and/or refractory B cell malignancies. However, in order to derive the desired level of effectiveness, patients need to successfully receive the CAR T cell infusion in a timely fashion. This process entails apheresis of the patient's T cells, followed by CAR T cell manufacture. While awaiting infusion at an authorized treatment centre, patients may receive interim disease-directed therapy. Most patients will also receive a course of pre-CAR T cell lymphodepletion, which has emerged as an important factor in enabling durable responses. The time between apheresis and CAR T cell infusion is often not a simple journey, with each milestone being a critical step that can have important downstream consequences for the ability to receive the infusion and the strength of clinical responses. In this Review, we provide a summary of the many considerations for preparing patients with B cell non-Hodgkin lymphoma or acute lymphoblastic leukaemia for CAR T cell therapy, and outline current limitations and areas for future research., (© 2022. Springer Nature Limited.)

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., (© 2022 by The American Society of Hematology.)

Chimeric antigen receptor (CAR) T cells have demonstrated promising efficacy, particularly in hematologic malignancies. One challenge regarding CAR T cells in solid tumors is the immunosuppressive tumor microenvironment (TME), characterized by high levels of multiple inhibitory factors, including transforming growth factor (TGF)-β. We report results from an in-human phase 1 trial of castration-resistant, prostate cancer-directed CAR T cells armored with a dominant-negative TGF-β receptor (NCT03089203). Primary endpoints were safety and feasibility, while secondary objectives included assessment of CAR T cell distribution, bioactivity and disease response. All prespecified endpoints were met. Eighteen patients enrolled, and 13 subjects received therapy across four dose levels. Five of the 13 patients developed grade ≥2 cytokine release syndrome (CRS), including one patient who experienced a marked clonal CAR T cell expansion, >98% reduction in prostate-specific antigen (PSA) and death following grade 4 CRS with concurrent sepsis. Acute increases in inflammatory cytokines correlated with manageable high-grade CRS events. Three additional patients achieved a PSA reduction of ≥30%, with CAR T cell failure accompanied by upregulation of multiple TME-localized inhibitory molecules following adoptive cell transfer. CAR T cell kinetics revealed expansion in blood and tumor trafficking. Thus, clinical application of TGF-β-resistant CAR T cells is feasible and generally safe. Future studies should use superior multipronged approaches against the TME to improve outcomes., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Despite improved outcomes achieved in the last decades for children with newly diagnosed leukaemia and lymphoma, treatment of patients with refractory/relapsed disease remains a challenge. The cure rate is still unsatisfactory and often achieved at the cost of significant morbidity. Exploring treatment with novel agents should offer less toxic therapeutic options, without compromising efficacy. Bispecific and antibody-drug conjugates targeting CD19 and CD22 (blinatumomab and inotuzumab ozogamicin) play an important role in the treatment of relapsed and refractory B-cell precursor acute lymphoblastic leukaemia (BCP-ALL); antibodies targeting CD123 and CD38 are also under investigation for acute myeloid leukaemia (AML) and T-ALL, respectively. Targeted therapy with small molecules is of primary importance for specific genetic subtypes, such as BCR-ABL-positive ALL, FLT3-ITD AML and anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma. KMT2A-directed targeted therapy with menin inhibitors holds promise to be of relevance in KMT2A-rearranged leukaemias, known to have dismal prognosis. Target inhibition in cellular pathways such as BCL-2, RAS, MEK, Bruton's tyrosine kinase, JAK-STAT or CDK4/CDK6 inhibition may be suitable for different diseases with common mutated pathways. Nevertheless, development and approval of new agents for paediatric cancers lags behind adult therapeutic options. New regulations were implemented to accelerate drug development for children. Considering the number of oncology medicinal products available for adults and the rarity of paediatric cancers, prioritisation based on scientific evidence and medical need, as well as international collaboration, is critical. Herein, we review the current status of drug development for children with leukaemia and lymphoma, excluding cellular therapy despite its well-known significance., Competing Interests: Conflict of interest statement The authors declare the following financial interests/personal relationships which may be considered potential competing interests: CMZ reports institutional funding was obtained from Pfizer, Jazz and Takeda to perform investigator-initiated studies with intent to file. Consultancy for Novartis, Takeda, Incyte, Roche Genentech. LG: advisory boards (unpaid) for Amgen, Genentech/Roche, Janssen, Kura and Pfizer; Stock/Stock options in Amgen, Mirati, OnKure and Sanofi Paris. SLM consulting, participation on advisory boards and study steering committees, clinical trial support: Novartis; Advisory board — Wugen. All other authors declare no conflict of interest., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

We assessed minimal residual disease (MRD) detection and B-cell aplasia after tisagenlecleucel therapy for acute lymphoblastic leukemia (ALL) to define biomarkers predictive of relapse ( N = 143). Next-generation sequencing (NGS) MRD detection >0 in bone marrow (BM) was highly associated with relapse. B-cell recovery [signifying loss of functional chimeric antigen receptor (CAR) T cells] within the first year of treatment was associated with a hazard ratio (HR) for relapse of 4.5 [95% confidence interval (CI), 2.03-9.97; P < 0.001]. Multivariate analysis at day 28 showed independent associations of BMNGS-MRD >0 (HR = 4.87; 95% CI, 2.18-10.8; P < 0.001) and B-cell recovery (HR = 3.33; 95% CI, 1.44-7.69; P = 0.005) with relapse. By 3 months, the BMNGS-MRD HR increased to 12 (95% CI, 2.87-50; P < 0.001), whereas B-cell recovery was not independently predictive (HR = 1.27; 95% CI, 0.33-4.79; P = 0.7). Relapses occurring with persistence of B-cell aplasia were largely CD19 - (23/25: 88%). Detectable BMNGS-MRD reliably predicts risk with sufficient time to consider approaches to relapse prevention such as hematopoietic cell transplantation (HCT) or second CAR-T cell infusion. SIGNIFICANCE: Detectable disease by BMNGS-MRD with or without B-cell aplasia is highly predictive of relapse after tisagenlecleucel therapy for ALL. Clonotypic rearrangements used to follow NGS-MRD did not change after loss of CD19 or lineage switch. High-risk patients identified by these biomarkers may benefit from HCT or investigational cell therapies. See related commentary by Ghorashian and Bartram, p. 2 . This article is highlighted in the In This Issue feature, p. 1 ., (©2021 The Authors; Published by the American Association for Cancer Research.)

Tisagenlecleucel is indicated for pediatric and young adult patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL) and adult patients with r/r diffuse large B-cell lymphoma (DLBCL). The tisagenlecleucel chimeric antigen receptor (CAR) contains a murine single-chain variable fragment domain; we examined the effects of humoral and cellular immune responses to tisagenlecleucel on clinical outcomes using 2 validated assays. Data were pooled from the ELIANA (registered at www.clinicaltrials.gov as #NCT02435849) and ENSIGN (#NCT02228096) trials in r/r B-ALL (N = 143) and the JULIET trial (#NCT02445248) in r/r DLBCL (N = 115). Humoral responses were determined by flow cytometric measurement of anti-murine CAR19 (mCAR19) antibodies in serum. Cellular responses were determined using T-cell production of interferon-γ in response to 2 different pools of mCAR19 peptides. Pretreatment anti-mCAR19 antibodies were detected in 81% of patients with r/r B-ALL and 94% of patients with r/r DLBCL. Posttreatment anti-mCAR19 antibodies were higher than patient-specific baseline in 42% of r/r B-ALL and 9% of r/r DLBCL patients. Pretreatment and posttreatment anti-mCAR19 antibodies did not affect tisagenlecleucel cellular kinetics, including maximum concentration and persistence (r2 < 0.05), clinical response (day-28 response, duration of response, and event-free survival), and safety. T-cell responses were consistent over time, with net responses <1% at baseline and posttreatment time points in a majority of patients and no effect on transgene expansion or persistence or outcomes. Presence of baseline and/or posttreatment anti-mCAR19 antibodies or T-cell responses did not alter the activity of tisagenlecleucel in patients with r/r B-ALL or r/r DLBCL., (© 2021 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background: CNS relapse of acute lymphocytic leukaemia is difficult to treat. Durable remissions of relapsed or refractory B-cell acute lymphocytic leukaemia have been observed following treatment with CD19-directed chimeric antigen receptor (CAR) T cells; however, most trials have excluded patients with active CNS disease. We aimed to assess the safety and activity of CAR T-cell therapy in patients with a history of CNS relapsed or refractory B-cell acute lymphocytic leukaemia., Methods: In this post-hoc analysis, we included 195 patients (aged 1-29 years; 110 [56%] male and 85 [44%] female) with relapsed or refractory CD19-positive acute lymphocytic leukaemia or lymphocytic lymphoma from five clinical trials (Pedi CART19, 13BT022, ENSIGN, ELIANA, and 16CT022) done at the Children's Hospital of Philadelphia (Philadelphia, PA, USA), in which participants received CD19-directed CAR T-cell therapy between April 17, 2012, and April 16, 2019. The trials required control of CNS disease at enrolment and infusion and excluded treatment in the setting of acute neurological toxic effects (>grade 1 in severity) or parenchymal lesions deemed to increase the risk of neurotoxicity. 154 patients from Pedi CART19, ELIANA, ENSIGN, and 16CT022 received tisagenlecleucel and 41 patients from the 13BT022 trial received the humanised CD19-directed CAR, huCART19. We categorised patients into two strata on the basis of CNS status at relapse or within the 12 months preceding CAR T-cell infusion-either CNS-positive or CNS-negative disease. Patients with CNS-positive disease were further divided on the basis of morphological bone marrow involvement-either combined bone marrow and CNS involvement, or isolated CNS involvement. Endpoints were the proportion of patients with complete response at 28 days after infusion, Kaplan-Meier analysis of relapse-free survival and overall survival, and the incidence of cytokine release syndrome and neurotoxicity., Findings: Of all 195 patients, 66 (34%) were categorised as having CNS-positive disease and 129 (66%) as having CNS-negative disease, and 43 (22%) were categorised as having isolated CNS involvement. The median length of follow-up was 39 months (IQR 25-49) in the CNS-positive stratum and 36 months (18-49) in the CNS-negative stratum. The proportion of patients in the CNS-positive stratum with a complete response at 28 days after infusion was similar to that in the CNS-negative stratum (64 [97%] of 66 vs 121 [94%] of 129; p=0·74), with no significant difference in relapse-free survival (60% [95% CI 49-74] vs 60% [51-71]; p=0·50) or overall survival (83% [75-93] vs 71% [64-79]; p=0·39) at 2 years between the two groups. Overall survival at 2 years was significantly higher in patients with isolated CNS involvement compared with those with bone marrow involvement (91% [82-100] vs 71% [64-78]; p=0·046). The incidence and severity of neurotoxicity (any grade, 53 [41%] vs 38 [58%]; grade 1, 24 [19%] vs 20 [30%]; grade 2, 14 [11%] vs 10 [15%]; grade 3, 12 [9%] vs 6 [9%], and grade 4, 3 [2%] vs 2 [3%]; p=0·20) and cytokine release syndrome (any grade, 110 [85%] vs 53 [80%]; grade 1, 12 [9%] vs 2 [3%]; grade 2, 61 [47%] vs 38 [58%]; grade 3, 18 [14%] vs 7 [11%] and grade 4, 19 [15%] vs 6 [9%]; p=0·26) did not differ between the CNS-negative and the CNS-positive disease strata., Interpretation: Tisagenlecleucel and huCART19 are active at clearing CNS disease and maintaining durable remissions in children and young adults with CNS relapsed or refractory B-cell acute lymphocytic leukaemia or lymphocytic lymphoma, without increasing the risk of severe neurotoxicity; although care should be taken in the timing of therapy and disease control to mitigate this risk. These preliminary findings support the use of these CAR T-cell therapies for patients with CNS relapsed or refractory B-cell acute lymphocytic leukaemia., Funding: Children's Hospital of Philadelphia Frontier Program., Competing Interests: Declaration of interests CC has served as a consultant for Novartis Pharmaceuticals. CHJ is an inventor of intellectual property, licensed by the University of Pennsylvania to Novartis; has received patent royalties; is a scientific co-founder of Tmunity Therapeutics and DeCART Therapeutics, for which he has founder's stock but no income; and is an advisor for AC Immune, Bluesphere Bio, Cellares, Celldex, Cabaletta, Carisma, Kiadis, Viracta, and Ziopharm. SAG has received research or clinical trial support, or both, from Novartis, Servier, and Kite, and has participated in consulting, in study steering committees, or in scientific or clinical advisory boards for Novartis, Cellectis, Adaptimmune, Eureka, TCR2, Juno, GlaxoSmithKline, Vertex, Humanigen, CBMG, Janssen/JnJ, Jazz Pharmaceuticals, Allogene, Cabaletta, and Roche. SRR has received research funding from and has served as a consultant for Pfizer, and a family member owns stock in Optinose. SLM has served as a consultant for Novartis Pharmaceuticals, Kite Pharma, and Wugen, and receives clinical trial funding from Novartis Pharmaceuticals. All other authors declare no competing interests., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Purpose: CD19-targeted chimeric antigen receptor (CAR)-modified T cells demonstrate unprecedented responses in B-cell acute lymphoblastic leukemia (B-ALL); however, relapse remains a substantial challenge. Short CAR T-cell persistence contributes to this risk; therefore, strategies to improve persistence are needed., Methods: We conducted a pilot clinical trial of a humanized CD19 CAR T-cell product (huCART19) in children and young adults with relapsed or refractory B-ALL (n = 72) or B-lymphoblastic lymphoma (n = 2), treated in two cohorts: with (retreatment, n = 33) or without (CAR-naive, n = 41) prior CAR exposure. Patients were monitored for toxicity, response, and persistence of huCART19., Results: Seventy-four patients 1-29 years of age received huCART19. Cytokine release syndrome developed in 62 (84%) patients and was grade 4 in five (6.8%). Neurologic toxicities were reported in 29 (39%), three (4%) grade 3 or 4, and fully resolved in all cases. The overall response rate at 1 month after infusion was 98% (100% in B-ALL) in the CAR-naive cohort and 64% in the retreatment cohort. At 6 months, the probability of losing huCART19 persistence was 27% (95% CI, 14 to 41) for CAR-naive and 48% (95% CI, 30 to 64) for retreatment patients, whereas the incidence of B-cell recovery was 15% (95% CI, 6 to 28) and 58% (95% CI, 33 to 77), respectively. Relapse-free survival at 12 and 24 months, respectively, was 84% (95% CI, 72 to 97) and 74% (95% CI, 60 to 90) in CAR-naive and 74% (95% CI, 56 to 97) and 58% (95% CI, 37 to 90) in retreatment cohorts., Conclusion: HuCART19 achieved durable remissions with long-term persistence in children and young adults with relapsed or refractory B-ALL, including after failure of prior CAR T-cell therapy., Competing Interests: David M. BarrettTravel, Accommodations, Expenses: Therakos David T. TeacheyConsulting or Advisory Role: SobiResearch Funding: Novartis, Beam Therapeutics, NeoImmuneTech Colleen CallahanConsulting or Advisory Role: NovartisSpeakers' Bureau: Peerview Susan R. RheingoldEmployment: OptiNoseStock and Other Ownership Interests: OptiNoseConsulting or Advisory Role: PfizerResearch Funding: Pfizer Richard AplencExpert Testimony: Vorys Pamela A. ShawPatents, Royalties, Other Intellectual Property: I am part of a patent owned by UPenn and currently licensed to Novartis for an algorithm that predicts severe cytokine release syndrome for the CART 19 therapy. I receive 10% of the licensing fees Edward PequignotPatents, Royalties, Other Intellectual Property: As part of Penn's role in the FDA-approval of CAR-T therapy, and for my part as an employee of Penn involved in their research in CAR-T, I have received royalties of approximately $300 in US dollars over the past 2 years Jennifer L. BrogdonEmployment: Novartis Institutes for BioMedical ResearchStock and Other Ownership Interests: Novartis Institutes for BioMedical Research Donald L. SiegelResearch Funding: Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: A patent, owned by the Trustees of the University of Pennsylvania, on which I am listed as an inventor is licensed to Alexion Pharmaceuticals. I receive royalties as stipulated in the University of Pennsylvania Faculty HandbookExpert Testimony: Regeneron Megan M. DavisLeadership: Cellares CorporationConsulting or Advisory Role: Tmunity Therapeutics IncResearch Funding: Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: Novartis Institutes for Biomedical Research—royalties and milestones for patents/knowhow, Tmunity Therapeutics—royalties andmilestones from patents/knowhow Simon F. LaceyConsulting or Advisory Role: Gilead SciencesResearch Funding: Tmunity Therapeutics Inc, Cabaletta Bio, Novartis Institutes for BioMedical ResearchPatents, Royalties, Other Intellectual Property: Patents and IP related to CTL019 (Kymriah) assigned by the University of Pennsylvania to Novartis Elizabeth O. HexnerConsulting or Advisory Role: Blueprint Medicines, ABIM Subspecialty BoardResearch Funding: Blueprint Medicines, Tmunity Therapeutics Inc Gerald B. WertheimEmployment: Johnson & JohnsonStock and Other Ownership Interests: Johnson & Johnson Bruce L. LevineStock and Other Ownership Interests: Tmunity Therapeutics IncHonoraria: Novartis, TerumoConsulting or Advisory Role: Avectas, Ori Biotech, Vycellix, Immuneel Therapeutics, In8bio, Patheon/ThermoFisher Viral Vector ServicesResearch Funding: Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: Intellectual property and patents in the field of cell and gene therapyTravel, Accommodations, Expenses: Avectas, Terumo Carl H. JuneLeadership: AC ImmuneStock and Other Ownership Interests: Celldex, Tmunity Therapeutics Inc, Cabaletta Bio, Carisma Therapeutics, DeCART Therapeutics, Bluesphere Bio, Cellares, ZIOPHARM Oncology, Decheng Capital, Posieda Therapeutics, VerismaHonoraria: PfizerConsulting or Advisory Role: Celldex, Viracta Therapeutics, Cabaletta Bio, Carisma Therapeutics, Kiadis Pharma, WIRB-Copernicus Group, Janssen OncologyResearch Funding: Novartis, Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: IP licensed to Novartis; Royalties paid to University of Pennsylvania, Office of Naval Research; IP and patent royalties, IP licensed to Tmunity Stephan A. GruppConsulting or Advisory Role: Novartis, Jazz Pharmaceuticals, Janssen, Cellular Biomedicine Group, TCR2 Therapeutics, Humanigen, Roche, Adaptimmune, Alimera Sciences, Cabaletta Bio, CRISPR Therapeutics/VertexResearch Funding: Novartis, Kite/Gilead, Servier, Jazz Pharmaceuticals, VertexPatents, Royalties, Other Intellectual Property: UPenn Toxicity management patentExpert Testimony: Juno Therapeutics Shannon L. MaudeConsulting or Advisory Role: Novartis, Wugen IncResearch Funding: NovartisTravel, Accommodations, Expenses: Novartis, Kite, a Gilead company, Wugen IncNo other potential conflicts of interest were reported.

Background: Tisagenlecleucel, an anti-CD19 chimeric antigen receptor T cell therapy, has demonstrated efficacy in children and young adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) in two multicenter phase 2 trials (ClinicalTrials.gov, NCT02435849 (ELIANA) and NCT02228096 (ENSIGN)), leading to commercialization of tisagenlecleucel for the treatment of patients up to age 25 years with B-ALL that is refractory or in second or greater relapse., Methods: A pooled analysis of 137 patients from these trials (ELIANA: n=79; ENSIGN: n=58) was performed to provide a comprehensive safety profile for tisagenlecleucel., Results: Grade 3/4 tisagenlecleucel-related adverse events (AEs) were reported in 77% of patients. Specific AEs of interest that occurred ≤8 weeks postinfusion included cytokine-release syndrome (CRS; 79% (grade 4: 22%)), infections (42%; grade 3/4: 19%), prolonged (not resolved by day 28) cytopenias (40%; grade 3/4: 34%), neurologic events (36%; grade 3: 10%; no grade 4 events), and tumor lysis syndrome (4%; all grade 3). Treatment for CRS included tocilizumab (40%) and corticosteroids (23%). The frequency of neurologic events increased with CRS severity (p<0.001). Median time to resolution of grade 3/4 cytopenias to grade ≤2 was 2.0 (95% CI 1.87 to 2.23) months for neutropenia, 2.4 (95% CI 1.97 to 3.68) months for lymphopenia, 2.0 (95% CI 1.87 to 2.27) months for leukopenia, 1.9 (95% CI 1.74 to 2.10) months for thrombocytopenia, and 1.0 (95% CI 0.95 to 1.87) month for anemia. All patients who achieved complete remission (CR)/CR with incomplete hematologic recovery experienced B cell aplasia; however, as nearly all responders also received immunoglobulin replacement, few grade 3/4 infections occurred >1 year postinfusion., Conclusions: This pooled analysis provides a detailed safety profile for tisagenlecleucel during the course of clinical trials, and AE management guidance, with a longer follow-up duration compared with previous reports., Competing Interests: Competing interests: JEL has received research and/or clinical trial support from Incyte, Kamada, Mesoblast, and Biogen and has participated in consulting, study steering committees, or scientific/clinical advisory boards for Novartis, bluebird bio, Incyte, Ironwood, Mesoblast, Omeros, Oncoimmune, Talaris, and X4 Pharmaceuticals. SAG has received research and/or clinical trial support from Novartis, Servier, and Kite and has participated in consulting, study steering committees, or scientific/clinical advisory boards for Novartis, Cellectis, Adaptimmune, Eureka, TCR2, Juno, GlaxoSmithKline, Vertex, Cure Genetics, Humanigen, and Roche. MAP has participated in steering committees for the ENSIGN and ELIANA trials for Novartis, advisory boards, and educational activities for Novartis. ACD is a current employee of bluebird bio; bluebird bio has had no support or oversight of this research or manuscript. SR has received clinical trial support from Novartis, Servier, and Celgene and has participated in consulting, study steering committees, or scientific/clinical advisory boards for Novartis, Servier, Celgene, Cellectis, Kite/Bristol-Myers Squibb, JazzPharma, and Amgen. GDM has received payment and honoraria as a consultant to Novartis Pharma and for serving on the speaker’s bureau for Kymriah. KJA has participated in a speaker bureau and received travel accommodations and expenses from Novartis. MRV has participated in advisory boards for Novartis, Fate Therapeutics, and B-Mogen and has stock options from Fate Therapeutics and B-Mogen. JB has participated in study steering committees, advisory boards, and educational activities for Novartis, and advisory boards for Kite and Janssen. TWL has consulted for Novartis, Cellectis, Loxo Oncology, Eli Lilly, and Bayer; has received research funding from Novartis, Pfizer, and Bayer; and is currently affiliated with the Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA and the Division of Oncology, Center for Childhood Cancer Research and Cancer Immunotherapy Program, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA. HB has participated in consulting for Novartis and Jazz Pharmaceuticals and his department has received financial reimbursement for participation in tisagenlecleucel trials for Novartis. AB has received research and/or clinical trial support from Novartis, Servier, and Kite and participated in consulting, study steering committees, or scientific/clinical advisory boards for Novartis, Servier, Celgene, Jazz Pharma, AstraZeneca, Janssen, and Amgen. MWB has participated in advisory boards for Novartis and Thunder Biotech. BDM has received a travel grant from Jazz Pharma; her department has received financial reimbursement and compensation for participation in CTL019 trials for Novartis, and consulting for Novartis. MQ has received support for service on clinical advisory boards for Novartis and Bristol-Myers Squibb. SMD has received research support from Alexion Pharmaceuticals and served in a consulting role for Novartis. CLP has received support for service on clinical advisory board for Novartis.TAD has no conflicts to declare. PB has received institutional research grants from medac, Riemser, and Neovii and institutional compensation for advisory activity and speakers bureau from Miltenyi, Amgen, Novartis, Servier, medac, and Riemser. KS has no conflicts to declare. PAW was an employee of Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA. RM has no conflicts to declare. LY is an employee of Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA. ML is an employee of Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA. LKE is an employee of Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA. CHJ has received research support from Novartis and Tmunity Therapeutics. SLM has received clinical trial support from Novartis and has served in a consulting role, on advisory boards, or on study steering committees for Novartis, Kite, and Wugen., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

While CD19-directed chimeric antigen receptor (CAR) T cells can induce remission in patients with B cell acute lymphoblastic leukemia (ALL), a large subset relapse with CD19 - disease. Like CD19, CD22 is broadly expressed by B-lineage cells and thus serves as an alternative immunotherapy target in ALL. Here we present the composite outcomes of two pilot clinical trials ( NCT02588456 and NCT02650414 ) of T cells bearing a 4-1BB-based, CD22-targeting CAR in patients with relapsed or refractory ALL. The primary end point of these studies was to assess safety, and the secondary end point was antileukemic efficacy. We observed unexpectedly low response rates, prompting us to perform detailed interrogation of the responsible CAR biology. We found that shortening of the amino acid linker connecting the variable heavy and light chains of the CAR antigen-binding domain drove receptor homodimerization and antigen-independent signaling. In contrast to CD28-based CARs, autonomously signaling 4-1BB-based CARs demonstrated enhanced immune synapse formation, activation of pro-inflammatory genes and superior effector function. We validated this association between autonomous signaling and enhanced function in several CAR constructs and, on the basis of these observations, designed a new short-linker CD22 single-chain variable fragment for clinical evaluation. Our findings both suggest that tonic 4-1BB-based signaling is beneficial to CAR function and demonstrate the utility of bedside-to-bench-to-bedside translation in the design and implementation of CAR T cell therapies.

CD19-directed chimeric antigen receptor (CAR) T cells show characteristic proliferation kinetics after infusion that correlate with response. Clearance of circulating disease, B-cell aplasia (BCA), and cytokine release syndrome (CRS) are used to observe CAR T-cell function, given the lack of commercial CAR T-cell measurement assays. We investigated the utility of common hematology laboratory parameters in 166 patients with B-cell acute lymphoblastic leukemia (B-ALL) who were treated with CAR T-cell therapy targeting CD19. CAR T-cell infusion was followed by disappearance of circulating blasts in 86% of patients at a median of 6 days. After a lag phase, there was a rapid expansion in absolute lymphocyte count (ALC) in the second week that coincided with the appearance of atypical lymphocytes. The expansion phase was followed by a contraction phase with a concomitant decrease in atypical lymphocytes. In vitro CAR T-cell studies showed similar kinetics and morphological changes. Peak ALC and overall expansion was greater in sustained responders compared with that in nonresponders. Patients with early loss of BCA and those with eventual CD19+ minimal residual disease/relapse showed lower overall lymphocyte expansion compared with the controls. Pleomorphic lymphocytosis was noted in the cerebrospinal fluid at post-CAR time points. We conclude that lymphocyte counts and differential can also be used to evaluate CAR T-cell expansion after infusion, along with BCA and CRS. This is the first report to characterize the morphology of CAR T cells and determine the utility of lymphocyte kinetics., (© 2021 by The American Society of Hematology.)

Purpose: To prospectively evaluate the effectiveness of risk-adapted preemptive tocilizumab (PT) administration in preventing severe cytokine release syndrome (CRS) after CTL019, a CD19 chimeric antigen receptor T-cell therapy., Methods: Children and young adults with CD19-positive relapsed or refractory B-cell acute lymphoblastic leukemia were assigned to high- (≥ 40%) or low- (< 40%) tumor burden cohorts (HTBC or LTBC) based on a bone marrow aspirate or biopsy before infusion. HTBC patients received a single dose of tocilizumab (8-12 mg/kg) after development of high, persistent fevers. LTBC patients received standard CRS management. The primary end point was the frequency of grade 4 CRS (Penn scale), with an observed rate of ≤ 5 of 15 patients in the HTBC pre-defined as clinically meaningful. In post hoc analyses, the HTBC was compared with a historical cohort of high-tumor burden patients from the initial phase I CTL019 trial., Results: The primary end point was met. Seventy patients were infused with CTL019, 15 in the HTBC and 55 in the LTBC. All HTBC patients received the PT intervention. The incidence of grade 4 CRS was 27% (95% CI, 8 to 55) in the HTBC and 3.6% (95% CI, 0.4 to 13) in the LTBC. The best overall response rate was 87% in the HTBC and 100% in the LTBC. Initial CTL019 expansion was greater in the HTBC than the LTBC ( P < .001), but persistence was not different ( P = .73). Event-free and overall survival were worse in the HTBC ( P = .004, P < .001, respectively). In the post hoc analysis, grade 4 CRS was observed in 27% versus 50% of patients in the PT and prior phase I cohorts, respectively ( P = .18)., Conclusion: Risk-adapted PT administration resulted in a decrease in the expected incidence of grade 4 CRS, meeting the study end point, without adversely impacting the antitumor efficacy or safety of CTL019.

Competing Interests: Conflict-of-interest disclosure: S.L.M. reports clinical trial support from Novartis and consulting, advisory boards, or study steering committee participation for Novartis, Kite, Wugen. A.C.T. reports no financial conflicts of interest.

For subgroups of children with B-cell acute lymphoblastic leukemia (B-ALL) at very high risk of relapse, intensive multiagent chemotherapy has failed. Traditionally, the field has turned to allogeneic hematopoietic stem cell transplantation (HSCT) for patients with poor outcomes. While HSCT confers a survival benefit for several B-ALL populations, often HSCT becomes standard-of-care in subsets of de novo ALL with poor risk features despite limited or no data showing a survival benefit in these populations, yet the additive morbidity and mortality can be substantial. With the advent of targeted immunotherapies and the transformative impact of CD19-directed chimeric antigen receptor (CAR)-modified T cells on relapsed or refractory B-ALL, this approach is currently under investigation in frontline therapy for a subset of patients with poor-risk B-ALL: high-risk B-ALL with persistent minimal residual disease at the end of consolidation, which has been designated very high risk. Comparisons of these 2 approaches are fraught with issues, including single-arm trials, differing eligibility criteria, comparisons to historical control populations, and vastly different toxicity profiles. Nevertheless, much can be learned from available data and ongoing trials. We will review data for HSCT for pediatric B-ALL in first remission and the efficacy of CD19 CAR T-cell therapy in relapsed or refractory B-ALL, and we will discuss an ongoing international phase 2 clinical trial of CD19 CAR T cells for very-high-risk B-ALL in first remission., Competing Interests: Conflict-of-interest disclosure: S.L.M. received clinical trial support from Novartis and participated in consulting, advisory boards, or study steering committees for Novartis, Kite, and Wugen. C.D. declares no competing financial interests., (© 2020 by The American Society of Hematology.)

Immune effector cell (IEC) therapies offer durable and sustained remissions in significant numbers of patients with hematological cancers. While these unique immunotherapies have improved outcomes for pediatric and adult patients in a number of disease states, as 'living drugs,' their toxicity profiles, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), differ markedly from conventional cancer therapeutics. At the time of article preparation, the US Food and Drug Administration (FDA) has approved tisagenlecleucel, axicabtagene ciloleucel, and brexucabtagene autoleucel, all of which are IEC therapies based on genetically modified T cells engineered to express chimeric antigen receptors (CARs), and additional products are expected to reach marketing authorization soon and to enter clinical development in due course. As IEC therapies, especially CAR T cell therapies, enter more widespread clinical use, there is a need for clear, cohesive recommendations on toxicity management, motivating the Society for Immunotherapy of Cancer (SITC) to convene an expert panel to develop a clinical practice guideline. The panel discussed the recognition and management of common toxicities in the context of IEC treatment, including baseline laboratory parameters for monitoring, timing to onset, and pharmacological interventions, ultimately forming evidence- and consensus-based recommendations to assist medical professionals in decision-making and to improve outcomes for patients., Competing Interests: Competing interests: CC─Consultant and/or advisory board: Novartis. MLD─Consultant and/or advisory board: Celyad, Novartis; Research/license support: Atara, Celgene; Stock option: Adaptive Biotechnologies, Precision Bioscience. CD─ Consultant and/or advisory board: Evidera, Juno. JD─Consultant and/or advisory board: Unum Therapeutics, Blue Earth Diagnostics; Royalties: Wolters Kluwer. JCF─NIDDK 23 grant. MJF─Consultant and/or advisory board: Arcelex, Celgene, Nkarta, Novartis, Xenetic Bio. JLH-C─At-large board member: ASTCT; Vice Chair: Government affairs, Task force member on Immunotherapies and Palliative Care, ASH; Co-Primary Investigator: Imaging trial haplo/cord, graft failure NHLBI RO1 grant. SAG─Consultant and/or advisory board: Adaptimmune, Allogene, Cellectis, Eureka, GlaxoSmithKline, Humanigen, J&J/Janssen, Juno, Novartis, Roche, TCR2, Vertex/CRISPR Therapeutics; Grant/research support: Kite Gilead, Novartis, Servier, Vertex. KVK─Consultant or SAB: Kite/Gilead, Autolus, Juno/BMS, Celgene, Novartis, Takeda, Kiadis, Incyte, Atara, Legend, Kadmon, Helocyte; Clinical trials support (institutional): Kite/Gilead, Novartis, Atara, Allogene; Nonprofit organizations: National Marrow Donor Program (Board of Directors), ASTCT (Chair, cell therapy committee). DWL─Owner: Immchase, LLC; Consultant and/or advisory board: ACI Clinical (on behalf of Celgene), Harpoon Therapeutics, Juno Therapeutics. FLL─Scientific advisor: Kite/Gilead, Novartis, BMS/Celgene, Allogene, Wugen, Calibr, Gamma Delta Therapeutics; Consultant: Cellular Biomedicine Group Inc; Research support: Kite/Gilead. SLM─Consultant and/or advisory board: Kite, Novartis. MVM─Consultant and/or advisory board: Adaptimmune, Adaptive Biotechnologies, Argentus, BD Sciences, Bluebird Bio, Cell Signaling, Collectis (SAB), CRISPR Therapeutics, EMD Serono, Inysus, Kite, Juno, MPM, Novartis, Takeda, TCR2 (SAB), Third Rock Ventures, WindMIL (SAB); Grant/research support: CRISPR Therapeutics, Kite Gilead. PLM─Consultant and/or advisory board: BlueBird Biotech, BMS, Celgene, Fate Therapeutics, Janssen, Juno, Karyopharm, Magenta Therapeutics, MedScape, Sanofi, Takeda. SSN─Consultant and/or advisory board: Celgene, Cell Medica, Incyte, Kite/Gilead, Merck, Novartis, Pfizer, Precision Biosciences, Unum Therapeutics; Grant/research support: Acerta, BMS, Collectis, Karus, Kite Gilead, Merck, Poseida, Unum Therapeutics. TGN─Consultant on imaging: Parexel, Intrinsic Imaging; SAB on Checkpoint and Myocarditis: BMS; Consultant: H3 Biomedicine, Aprea Therapeutics. BDS─Consultant and/or advisory board: Kite Gilead, Juno/Celgene, Insysus, Novartis, Janssen; Grant/research support: ADC Therapeutics. EJS─Consultant and/or advisory board: Adaptimmune, Cellgene, Magenta, Novartis, Partner Therapeutics. DTT─Advisory board: La Roche, Amgen, Janssen, Novartis. CJT─Consultant and/or advisory board: Aptevo, Arsenal Bio, AstraZeneca, Caribou Biosciences, Century Therapeutics, Eureka Therapeutics, Humanigen, Juno/BMS, Kite/Gilead, Myeloid Therapeutics, Nektar Therapeutics, Novartis, Precision Biosciences, T-CURX; Stock options: Precision Biosciences, Eureka Therapeutics, Caribou Biosciences, Arsenal Bio, Myeloid Therapeutics; Grant/research support: Juno/BMS, Nektar Therapeutics, AstraZeneca. SA, MRB, JNB, TJF, EM, and TW─Nothing to disclose. SITC staff: AK, BL, LL and SMW─Nothing to disclose., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Chimeric antigen receptor (CAR) T-cells directed against CD19 have drastically altered outcomes for children with relapsed and refractory acute lymphoblastic leukemia (r/r ALL). Pediatric patients with r/r ALL treated with CAR-T are at increased risk of both cytokine release syndrome (CRS) and sepsis. We sought to investigate the biologic differences between CRS and sepsis and to develop predictive models which could accurately differentiate CRS from sepsis at the time of critical illness. We identified 23 different cytokines that were significantly different between patients with sepsis and CRS. Using elastic net prediction modeling and tree classification, we identified cytokines that were able to classify subjects as having CRS or sepsis accurately. A markedly elevated interferon γ (IFNγ) or a mildly elevated IFNγ in combination with a low IL1β were associated with CRS. A normal to mildly elevated IFNγ in combination with an elevated IL1β was associated with sepsis. This combination of IFNγ and IL1β was able to categorize subjects as having CRS or sepsis with 97% accuracy. As CAR-T therapies become more common, these data provide important novel information to better manage potential associated toxicities., (© 2020 by The American Society of Hematology.)

Primary resistance to CD19-directed chimeric antigen receptor T-cell therapy (CART19) occurs in 10% to 20% of patients with acute lymphoblastic leukemia (ALL); however, the mechanisms of this resistance remain elusive. Using a genome-wide loss-of-function screen, we identified that impaired death receptor signaling in ALL led to rapidly progressive disease despite CART19 treatment. This was mediated by an inherent resistance to T-cell cytotoxicity that permitted antigen persistence and was subsequently magnified by the induction of CAR T-cell functional impairment. These findings were validated using samples from two CAR T-cell clinical trials in ALL, where we found that reduced expression of death receptor genes was associated with worse overall survival and reduced T-cell fitness. Our findings suggest that inherent dysregulation of death receptor signaling in ALL directly leads to CAR T-cell failure by impairing T-cell cytotoxicity and promoting progressive CAR T-cell dysfunction. SIGNIFICANCE: Resistance to CART19 is a significant barrier to efficacy in the treatment of B-cell malignancies. This work demonstrates that impaired death receptor signaling in tumor cells causes failed CART19 cytotoxicity and drives CART19 dysfunction, identifying a novel mechanism of antigen-independent resistance to CAR therapy. See related commentary by Green and Neelapu, p. 492 ., (©2020 American Association for Cancer Research.)

Twenty-eight patients were maintained on subcutaneous immunoglobulin replacement for persistent B-cell aplasia and agammaglobulinemia following CD19-targeted chimeric antigen receptor T-cell therapy for B-cell lymphoblastic leukemia. Patients were transitioned from intravenous to subcutaneous immunoglobulin replacement at a median of 11.5 months (range, 4-20). Increasing serum IgG level was significantly associated with a lower rate of sinopulmonary infection (P = 0.0072). The median serum IgG level during infection-free periods was 1000 mg/dL (range, 720-1430), which was significantly higher than IgG levels in patients with sinopulmonary infections. As such, we recommend maintaining a goal IgG level > 1000 mg/dL to provide optimal protection., (© 2019 Wiley Periodicals, Inc.)

Although many children and young adults with B-cell acute lymphoblastic leukemia (B-ALL) are cured with modern, risk-adapted chemotherapy regimens, 10% to 15% of patients will experience relapse or have refractory disease. Recent efforts to further intensify cytotoxic chemotherapy regimens in the frontline setting have failed as a result of excessive toxicity or lack of improvement in efficacy. As a result, novel approaches will be required to achieve cures in more newly diagnosed patients. Multiple immune-based therapies have demonstrated considerable efficacy in the setting of relapsed or refractory (R/R) disease, including CD19 targeting with blinatumomab and tisagenlecleucel and CD22 targeting with inotuzumab ozogamicin. These agents are now under investigation by the Children's Oncology Group (COG) in clinical trials for newly diagnosed B-ALL, with integration into standard chemotherapy regimens based on clinically and biology-based risk stratification as well as disease response.

Purpose: The anti-CD19 chimeric antigen receptor T-cell therapy tisagenlecleucel (CTL019) has an 81% response rate in children with relapsed or chemotherapy refractory (r/r) B-cell acute lymphoblastic leukemia (ALL). Cytokine release syndrome (CRS) is a life-threatening treatment-related toxicity that limits the full therapeutic potential in adults. We report outcomes for adults with r/r ALL treated with an optimized CTL019 dosing and CRS management strategy., Methods: Adults with r/r B-cell ALL received CTL019 in 1 of 2 trials. Patients received lymphodepletion followed by CTL019 as either a one-time infusion or fractionated infusions split over 3 days (day 1, 10%; day 2, 30%; day 3, 60%), which allowed for day 2 and day 3 doses to be held for early CRS. Total planned CTL019 dose varied with adaptive protocol modifications in response to efficacy and CRS toxicity., Results: Thirty-five adults with r/r ALL received CTL019 in 1 of 3 dosing cohorts. The low-dose cohort (n = 9) received single or fractionated dosing and had manageable toxicity with a 33% complete remission (CR) rate. In the high-dose single infusion cohort, 3 of 6 patients with refractory CRS concurrent with culture-positive sepsis died, and 3 achieved CR. The 20 patients in the high-dose fractionated (HDF) cohort had a 90% CR rate and manageable CRS. The HDF cohort had the highest survival, with a 2-year overall survival of 73% (95% CI, 46% to 88%) and event-free survival of 49.5% (95% CI, 21% to 73%)., Conclusion: Fractionated dosing of CTL019 with intrapatient dose modification optimizes safety without compromising efficacy in adults with r/r ALL.

Chimeric antigen receptor-engineered T cells targeting CD19 (CART19) provide an effective treatment for pediatric acute lymphoblastic leukemia but are less effective for chronic lymphocytic leukemia (CLL), focusing attention on improving efficacy. CART19 harbor an engineered receptor, which is delivered through lentiviral vector integration, thereby marking cell lineages and modifying the cellular genome by insertional mutagenesis. We recently reported that vector integration within the host TET2 gene was associated with CLL remission. Here, we investigated clonal population structure and therapeutic outcomes in another 39 patients by high-throughput sequencing of vector-integration sites. Genes at integration sites enriched in responders were commonly found in cell-signaling and chromatin modification pathways, suggesting that insertional mutagenesis in these genes promoted therapeutic T cell proliferation. We also developed a multivariate model based on integration-site distributions and found that data from preinfusion products forecasted response in CLL successfully in discovery and validation cohorts and, in day 28 samples, reported responders to CLL therapy with high accuracy. These data clarify how insertional mutagenesis can modulate cell proliferation in CART19 therapy and how data on integration-site distributions can be linked to treatment outcomes.

Tisagenlecleucel, a chimeric antigen receptor (CAR) T-cell product targeting CD19 is approved for relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, the impact of pretreatment variables, such as CD19 expression level, on leukemic blasts, the presence of CD19- subpopulations, and especially prior CD19-targeted therapy, on the response to CAR T-cell therapy has not been determined. We analyzed 166 patients treated with CAR T-cell therapy at our institution. Eleven patients did not achieve a minimal residual disease (MRD)- deep remission, whereas 67 patients had a recurrence after achieving a MRD- deep remission: 28 patients with CD19+ leukemia and 39 patients with CD19- leukemia. Return of CD19+ leukemia was associated with loss of CAR T-cell function, whereas CD19- leukemia was associated with continued CAR T-cell function. There were no significant differences in efficacy of CAR T cells in CD19-dim B-ALL, compared with CD19-normal or -bright B-ALL. Consistent with this, CAR T cells recognized and lysed cells with very low levels of CD19 expression in vitro. The presence of dim CD19 or rare CD19- events by flow cytometry did not predict nonresponse or recurrence after CAR T-cell therapy. However, prior therapy with the CD19-directed, bispecific T-cell engager blinatumomab was associated with a significantly higher rate of failure to achieve MRD- remission or subsequent loss of remission with antigen escape. Finally, immunophenotypic heterogeneity and lineage plasticity were independent of underlying clonotype and cytogenetic abnormalities., (© 2019 by The American Society of Hematology.)

Chimeric antigen receptor (CAR)-modified T-cell therapy has revolutionized the care of patients with relapsed and refractory B-cell acute lymphoblastic leukemia (B-ALL). Results from clinical trials across multiple institutions report remarkable remission rates with CD19-directed CAR-modified T-cell therapy. These remissions are also proving to be durable in many patients with a relapse-free survival (RFS) of approximately 50% to 60% at 1 year across several trials and institutions in this population that has been historically very difficult to treat. In addition, new products are being developed to enhance upon the original CAR T-cell products, which include a humanized CAR, allogeneic CARs, and both CD22 and biallelic CD19 and CD22 constructs. Toxicity after CAR-modified T-cell therapy is characterized by cytokine release syndrome (CRS) and neurotoxicity in the acute post-infusion period and B-cell aplasia as a long-term consequence of treatment. This review will summarize the published data thus far on the use of CAR-modified T-cell therapy in pediatric B-ALL and outline the various CAR products now being developed for this population. Delivery of this therapy and the decision to pursue hematopoietic stem cell transplant (HSCT) after treatment will be discussed., Competing Interests: Both AD and SM participated in the writing and revising of the manuscript. AD has no relevant conflicts of interest to disclose. SM reports honoraria for advisory boards from Novartis Pharmaceuticals and Kite Pharma, Inc. and institutional funding (research support) from Novartis Pharmaceuticals., (Copyright © 2019 the Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the European Hematology Association.)

Philadelphia chromosome-like (Ph-like) acute lymphoblastic leukemia (ALL) is a genetically heterogeneous subtype of B-cell ALL characterized by chromosomal rearrangements and mutations that result in aberrant cytokine receptor and kinase signaling. In particular, chromosomal rearrangements resulting in the overexpression of cytokine receptor-like factor 2 (CRLF2) occur in 50% of Ph-like ALL cases. CRLF2 overexpression is associated with particularly poor clinical outcomes, though the molecular basis for this is currently unknown. Glucocorticoids (GCs) are integral to the treatment of ALL and GC resistance at diagnosis is an important negative prognostic factor. Given the importance of GCs in ALL therapy and the poor outcomes for patients with CRLF2 overexpression, we hypothesized that the aberrant signal transduction associated with CRLF2 overexpression might mediate intrinsic GC insensitivity. To test this hypothesis, we exposed Ph-like ALL cells from patient-derived xenografts to GCs and found that CRLF2 rearranged (CRLF2R) leukemias uniformly demonstrated reduced GC sensitivity in vitro. Furthermore, targeted inhibition of signal transduction with the MEK inhibitor trametinib and the Akt inhibitor MK2206, but not the JAK inhibitor ruxolitinib, was sufficient to augment GC sensitivity. These data suggest that suboptimal GC responses may in part underlie the poor clinical outcomes for patients with CRLF2 overexpression and provide rationale for combination therapy involving GCs and signal transduction inhibitors as a means of enhancing GC efficacy., Competing Interests: The authors have declared that no competing interests exist.

Purpose: Tisagenlecleucel is an anti-CD19 chimeric antigen receptor (CAR19) T-cell therapy approved for the treatment of children and young adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL)., Patients and Methods: We evaluated the cellular kinetics of tisagenlecleucel, the effect of patient factors, humoral immunogenicity, and manufacturing attributes on its kinetics, and exposure-response analysis for efficacy, safety and pharmacodynamic endpoints in 79 patients across two studies in pediatric B-ALL (ELIANA and ENSIGN)., Results: Using quantitative polymerase chain reaction to quantify levels of tisagenlecleucel transgene, responders ( N = 62) had ≈2-fold higher tisagenlecleucel expansion in peripheral blood than nonresponders ( N = 8; 74% and 104% higher geometric mean Cmax and AUC0-28d, respectively) with persistence measurable beyond 2 years in responding patients. Cmax increased with occurrence and severity of cytokine release syndrome (CRS). Tisagenlecleucel continued to expand and persist following tocilizumab, used to manage CRS. Patients with B-cell recovery within 6 months had earlier loss of the transgene compared with patients with sustained clinical response. Clinical responses were seen across the entire dose range evaluated (patients ≤50 kg: 0.2 to 5.0 × 10 6 /kg; patients >50 kg: 0.1 to 2.5 × 10 8 CAR-positive viable T cells) with no relationship between dose and safety. Neither preexisting nor treatment-induced antimurine CAR19 antibodies affected the persistence or clinical response., Conclusions: Response to tisagenlecleucel was associated with increased expansion across a wide dose range. These results highlight the importance of cellular kinetics in understanding determinants of response to chimeric antigen receptor T-cell therapy., (©2018 American Association for Cancer Research.)

We report a patient relapsing 9 months after CD19-targeted CAR T cell (CTL019) infusion with CD19 - leukemia that aberrantly expressed the anti-CD19 CAR. The CAR gene was unintentionally introduced into a single leukemic B cell during T cell manufacturing, and its product bound in cis to the CD19 epitope on the surface of leukemic cells, masking it from recognition by and conferring resistance to CTL019.

Introduction: Cure rates for pediatric and young adult patients with refractory or recurrently relapsed acute lymphoblastic leukemia (ALL) are dismal. Survival from time of relapse is typically measured in weeks to months, and standard chemotherapy and currently approved targeted therapy achieve remission in less than a third of affected patients. To date, the only definitive curative therapy has been allogeneic hematopoietic stem cell transplant (HSCT). Advances in immunotherapy, with the introduction of chimeric antigen receptor T-cell therapies and the development of tisagenlecleucel, have changed the landscape. Areas covered: This review will describe the pharmacology of tisagenlecleucel and summarize the clinical evidence for its use in the treatment of multiple-relapsed or refractory B-cell ALL (B-ALL). Also discussed are other immunotherapies for B-ALL as well as the most commonly-encountered toxicities and corresponding management strategies. Expert commentary: Early phase trials indicate that tisagenlecleucel significantly improves survival for patients with B-ALL that is refractory or in second or later relapse. In responding patients, remissions have been reported on the order of years, and thus, tisagenlecleucel may herald a dramatic shift in the treatment paradigm of this largely fatal disease.