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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.

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.

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.

Background Clinicians are the standard source for adverse event (AE) reporting in oncology trials, despite the subjective nature of symptomatic AEs. The authors designed a pediatric patient-reported outcome (PRO) instrument for symptomatic AEs to support the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) (the Pediatric PRO-CTCAE). The current study developed a standardized algorithm that maps all possible Pediatric PRO-CTCAE response patterns to recommended CTCAE grades to improve the accuracy of AE reporting in pediatric oncology trials. Methods Two rounds of surveys were administered to experienced cancer clinicians across 9 pediatric hospitals. In round 1, pediatric oncologists assigned CTCAE grades to all 101 possible Pediatric PRO-CTCAE response patterns. The authors evaluated clinician agreement of CTCAE grades across response patterns and categorized each response pattern as having high or low agreement. In round 2, a survey was sent to a larger clinician group to examine clinician agreement among a select set of Pediatric PRO-CTCAE response patterns, and the authors examined how clinical context influenced grade assignment. Results A total of 10 pediatric oncologists participated in round 1. Of the 101 possible patterns, 89 (88%) had high agreement. The Light weighted kappa was averaged across the 10 oncologists (Light kappa = 0.73; 95% CI, 0.66-0.81). A total of 139 clinicians participated in round 2. High clinician agreement remained for the majority of generic response patterns and the clinical context did not typically change grades but rather improved agreement. Conclusions The current study provides a framework for integrating child self-reported symptom data directly into mandated AE reporting in oncology trials. Translating Pediatric PRO-CTCAE responses into clinically meaningful metrics will guide future cancer care and toxicity grading.

Purpose Late cardiotoxicity after pediatric acute myeloid leukemia therapy causes substantial morbidity and mortality. The impact of early-onset cardiotoxicity on treatment outcomes is less well understood. Thus, we evaluated the risk factors for incident early cardiotoxicity and the impacts of cardiotoxicity on event-free survival (EFS) and overall survival (OS). Methods Cardiotoxicity was ascertained through adverse event monitoring over the course of follow-up among 1,022 pediatric patients with acute myeloid leukemia treated in the Children’s Oncology Group trial AAML0531. It was defined as grade 2 or higher left ventricular systolic dysfunction on the basis of Common Terminology Criteria for Adverse Events (version 3) definitions. Results Approximately 12% of patients experienced cardiotoxicity over a 5-year follow-up, with more than 70% of incident events occurring during on-protocol therapy. Documented cardiotoxicity during on-protocol therapy was significantly associated with subsequent off-protocol toxicity. Overall, the incidence was higher among noninfants and black patients, and in the setting of a bloodstream infection. Both EFS (hazard ratio [HR], 1.6; 95% CI, 1.2 to 2.1; P = .004) and OS (HR, 1.6; 95% CI, 1.2 to 2.2, P = .005) were significantly worse in patients with documented cardiotoxicity. Impacts on EFS were equivalent whether the incident cardiotoxicity event occurred in the absence (HR, 1.6; 95% CI, 1.1 to 2.2; P = .017) or presence of infection (HR, 1.6; 95% CI, 1.0 to 2.7; P = .069) compared with patients without documented cardiotoxicity. However, the reduction in OS was more pronounced for cardiotoxicity not associated with infection (HR, 1.7; 95% CI, 1.2 to 2.5; P = .004) than for infection-associated cardiotoxicity (HR, 1.3; 95% CI, 0.7 to 2.4; P = .387). Conclusion Early treatment-related cardiotoxicity may be associated with decreased EFS and OS. Cardioprotective strategies are urgently needed to improve relapse risk and both short- and long-term mortality outcomes.

Background Using patient-reported outcomes for symptom monitoring in oncology has resulted in significant benefits for adult patients with cancer. The feasibility of this approach has not been established in the routine care of children with cancer. Methods The Pediatric Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (Ped-PRO-CTCAE) is an item library that enables children and caregivers to self-report symptoms. Ten symptom items from the Ped-PRO-CTCAE were uploaded to an online platform. Patients at least 7 years old and their caregivers were prompted by text/email message to electronically self-report daily during a planned hospitalization for chemotherapy administration. Symptom reports were emailed to the clinical team caring for the patient, but no instructions were given regarding the use of this information. Rates of patient participation and clinician responses to reports were systematically tracked. Results The median age of the participating patients (n = 52) was 11 years (range, 7-18 years). All patients and caregivers completed an initial login, with 92% of dyads completing at least 1 additional symptom assessment during hospitalization (median, 3 assessments; range, 0-40). Eighty-one percent of participating dyads submitted symptom reports on at least half of hospital days, and 54% submitted reports on all hospital days. Clinical actions were taken in response to symptom reports 21% of the time. Most patients felt that the system was easy (73%) and important (79%). Most clinicians found symptom reports easy to understand and useful (97%). Conclusions Symptom monitoring using patient-reported outcome measures for hospitalized pediatric oncology patients is feasible and generates data valued by clinicians and patients.

PURPOSETo 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.METHODSChildren 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.RESULTSThe 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).CONCLUSIONRisk-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.

As clinical advances with chimeric antigen receptor (CAR) T cells are increasingly described and the potential for extending their therapeutic benefit grows, optimizing the implementation of this therapeutic modality is imperative. The recognition and management of cytokine release syndrome (CRS) marked a milestone in this field; however, beyond the understanding gained in treating CRS, a host of additional toxicities and/or potential late effects of CAR T cell therapy warrant further investigation. A multicentre initiative involving experts in paediatric cell therapy, supportive care and/or study of late effects from cancer and haematopoietic stem cell transplantation was convened to facilitate the comprehensive study of extended CAR T cell-mediated toxicities and establish a framework for new systematic investigations of CAR T cell-related adverse events. Together, this group identified six key focus areas: extended monitoring of neurotoxicity and neurocognitive function, psychosocial considerations, infection and immune reconstitution, other end organ toxicities, evaluation of subsequent neoplasms, and strategies to optimize remission durability. Herein, we present the current understanding, gaps in knowledge and future directions of research addressing these CAR T cell-related outcomes. This systematic framework to study extended toxicities and optimization strategies will facilitate the translation of acquired experience and knowledge for optimal application of CAR T cell therapies. A host of additional toxicities and/or potential late effects of chimeric antigen receptor (CAR) T cell therapy beyond cytokine release syndrome (CRS) warrant further investigation. Herein, experts in paediatric cell therapy, supportive care and/or study of late effects from cancer and haematopoietic stem cell transplantation present six key focus research areas related to CAR T cell-related outcomes beyond CRS.

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.

Background: Anti-CD19 Chimeric Antigen Receptor (CAR) T cell therapy has emerged as a mainstay in the treatment of patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (ALL). While trials have shown encouraging survival rates, up to 50% of patients receiving CART eventually relapse. Identification of risk factors for subsequent relapse is crucial, as this could allow tailored surveillance and treatment approaches for high-risk patients, potentially leading to improved morbidity and mortality. Complete remission with incomplete hematologic recovery (CRi) has been associated with decreased remission duration and overall survival in acute leukemias. As count suppression following CAR T cell therapy is frequently seen, this study evaluated CRi as a prognostic marker for worse relapse-free (RFS) and overall survival (OS) after CAR T cell therapy in comparison to complete remission with hematologic recovery (CR). Methods: Patients with r/r ALL who achieved a complete morphologic remission after receiving anti-CD19 CAR T cell treatment with the 4-1BB-containing products CTL019 or humanized CART19 in the context of a clinical trial (NCT01626495, NCT02374333, NCT02228096, NCT02435849, NCT02906371) or commercial product (tisagenlecleucel) at Children's Hospital of Philadelphia from 4/2012-4/2019 were identified. Patients who received prior CAR therapy, and those with Trisomy 21 were excluded. Demographic, disease and treatment characteristics, and outcome data were abstracted from the medical record or clinical trial datasets. CR was defined as achieving a morphologic remission with both an absolute neutrophil count (ANC) ≥1,000/µL and a transfusion-independent platelet count ≥100,000/µL at any time between 27-33 days after CAR T cell infusion, whereas those achieving a morphologic remission without complete hematologic recovery were defined as CRi. RFS and OS were described for each cohort. Exposure-outcome association was assessed via the log-rank test and multivariable Cox proportional hazard regression. Results: Of the 206 patients included in the analysis, 104 (51%) achieved CR, 102 (49%) CRi. Forty patients (39%) met criteria for CRi with both ANC 25% bone marrow blasts (43% vs 19%) at infusion, whereas more CR patients were MRD-negative (50% vs 30%) at infusion (p=0.002). CRi patients were also more likely to have Grade 3/4 CRS (38% vs 6.7%). Median length of follow-up for patients with CR was 39 months (range 7-89), which was not statistically significantly different than for those patients with CRi (41 months, 11-98, p=0.875). There was no difference in RFS when stratified by hematologic recovery (Figure 1, p=0.2165), with RFS at 36 months for CR of 57% (47-69) and CRi of 46% (36-59). OS was significantly lower (Figure 2, p=0.0081) for those with CRi, with 36-month OS for CR of 81% (74-89), and for CRi of 63% (54-73). In multivariable analysis adjusting for sex, prior blinatumomab, relapse number, disease burden at infusion, and maximum CRS grade, CR was not associated with either RFS (HR 0.76 [95%CI 0.50-1.17] p=0.2182) or OS (HR 0.74 [95%CI 0.43-1.29] p=0.2908), in comparison to CRi, Table 2. Discussion: Complete remission with incomplete hematologic recovery, manifesting as neutropenia and/or thrombocytopenia, at the first disease assessment following CAR T cell infusion should not be regarded as a harbinger of relapse and demonstrates that patients with CRi have similar probability of durable remission without further therapy. Anticipatory guidance should be provided to patients, and their families, that CRi is more frequently seen in patients who experience high grade CRS, who have high disease burden at infusion, and who are treated in first relapse. Figure 1 Figure 1. Disclosures Callahan: Novartis: Speakers Bureau. Rheingold: Optinose: Other: Spouse's current employment; Pfizer: Research Funding. Grupp: Novartis, Roche, GSK, Humanigen, CBMG, Eureka, and Janssen/JnJ: Consultancy; Novartis, Adaptimmune, TCR2, Cellectis, Juno, Vertex, Allogene and Cabaletta: Other: Study steering committees or scientific advisory boards; Novartis, Kite, Vertex, and Servier: Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Steering committee, Research Funding. Maude: Wugen: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding.

Background Patient-reported outcomes (PROs) are captured within cancer trials to help future patients and their clinicians make more informed treatment decisions. However, variability in standards of PRO trial design and reporting threaten the validity of these endpoints for application in clinical practice. Methods We systematically investigated a cohort of randomized controlled cancer trials that included a primary or secondary PRO. For each trial, an evaluation of protocol and reporting quality was undertaken using standard checklists. General patterns of reporting where also explored. Results Protocols (101 sourced, 44.3%) included a mean (SD) of 10 (4) of 33 (range = 2–19) PRO protocol checklist items. Recommended items frequently omitted included the rationale and objectives underpinning PRO collection and approaches to minimize/address missing PRO data. Of 160 trials with published results, 61 (38.1%, 95% confidence interval = 30.6% to 45.7%) failed to include their PRO findings in any publication (mean 6.43-year follow-up); these trials included 49 568 participants. Although two-thirds of included trials published PRO findings, reporting standards were often inadequate according to international guidelines (mean [SD] inclusion of 3 [3] of 14 [range = 0–11]) CONSORT PRO Extension checklist items). More than one-half of trials publishing PRO results in a secondary publication (12 of 22, 54.5%) took 4 or more years to do so following trial closure, with eight (36.4%) taking 5–8 years and one trial publishing after 14 years. Conclusions PRO protocol content is frequently inadequate, and nonreporting of PRO findings is widespread, meaning patient-important information may not be available to benefit patients, clinicians, and regulators. Even where PRO data are published, there is often considerable delay and reporting quality is suboptimal. This study presents key recommendations to enhance the likelihood of successful delivery of PROs in the future.

10511 Background: CNS relapse of B-ALL is difficult to treat after cranial radiation or multiple relapses. Durable remissions of relapsed/refractory (r/r) B-ALL have been seen with CD19 CAR T cells; however, most trials excluded patients with active CNS disease. As we observed CAR trafficking into the CSF, we hypothesized that CD19 CAR T cells could control CNS B-ALL. Methods: We identified children and young adults with r/r CNS B-ALL treated on 4 clinical trials of CD19 CAR T cells, CTL019 or CTL119. NCT01626495 and NCT02435849 excluded active CNS disease, while the former in an amendment as well as NCT02374333 and NCT02906371 permitted active CNS disease controlled on therapy. All trials permitted CNS disease that cleared and excluded bulky intracranial disease that did not improve. We analyzed outcomes (CR, RFS) and safety. Results: We identified 65 patients 1-29y (median 10y) with r/r CNS B-ALL (CNS+) of 182 treated with CTL019/CTL119. There were no differences in age, sex, history of SCT or neurologic comorbidities in the CNS+ and CNS- cohorts. CNS+ patients were more likely to be in ≥2nd relapse (74% vs 46%, p < 0.01), to have received cranial radiation (58% vs 11%, p < 0.01), to have detectable CNS disease (p = 0.02) and less bone marrow disease pre-infusion (p < 0.01). At 1 mo post infusion, 62 (95%) CNS+ and 110 (94%) CNS- patients were in CR; 1 in each cohort died of sequelae of CRS and was inevaluable for response. All patients with CNS disease detected pre-infusion cleared by mo 3, including 9 in the CNS+ cohort [5 CNS2 ( < 5 CSF WBC with blasts), 4 CNS3 ( > 5 CSF WBC with blasts or exam/imaging evidence)] and 8 in the CNS- cohort (isolated CNS2 status pre-infusion). There was no difference in RFS (p = 0.28) in the CNS+ and CNS- cohorts [24-mo RFS: 61% (95% CI 46-73%) and 60% (95% CI 48-70%)]. There were 4 CNS relapses in the CNS+ cohort, and 1 in the CNS- cohort. Encephalopathy rate and grade was similar in the CNS+ and CNS- cohorts (52% vs 40% any grade; 12% vs 11% grade 3/4; p = 0.41). There were no deaths due to neurotoxicity (NT) and no statistically significant differences in incidence or severity of any NT or CRS in the CNS+ and CNS- cohorts. Conclusions: The CD19 CAR T cell therapies CTL019/CTL119 are effective at clearing CNS disease and inducing durable remissions in children and young adults with r/r CNS B-ALL. CNS relapse rates are low ( < 3%). Most CD19 CAR T cell trials excluded patients with active CNS disease, primarily due to the risk of NT. We show that patients with r/r CNS B-ALL that is adequately controlled prior to infusion can be safely treated with CD19 CAR T cells, with no increased risk of NT. Clinical trial information: NCT01626495, NCT02435849, NCT02374333, NCT02906371.

Background: In the United States, cancer is common, with high morbidity and mortality; cancer incidence varies between states. Online searches reflect public awareness, which could be driven by the underlying regional cancer epidemiology. Objective: The objective of our study was to characterize the relationship between cancer incidence and online Google search volumes in the United States for 6 common cancers. A secondary objective was to evaluate the association of search activity with cancer-related public events and celebrity news coverage. Methods: We performed a population-based, retrospective study of state-level cancer incidence from 2004 through 2013 reported by the Centers for Disease Control and Prevention for breast, prostate, colon, lung, and uterine cancers and leukemia compared to Google Trends (GT) relative search volume (RSV), a metric designed by Google to allow interest in search topics to be compared between regions. Participants included persons in the United States who searched for cancer terms on Google. The primary measures were the correlation between annual state-level cancer incidence and RSV as determined by Spearman correlation and linear regression with RSV and year as independent variables and cancer incidence as the dependent variable. Temporal associations between search activity and events raising public awareness such as cancer awareness months and cancer-related celebrity news were described. Results: At the state level, RSV was significantly correlated to incidence for breast (r=.18, P=.001), prostate (r=–.27, P

Vincristine (VCR) is a vinca alkaloid and common chemotherapeutic that is used to treat multiple pediatric and adult malignancies. Despite its common use, cases of anaphylaxis to VCR are rare and typically isolated to a single individual. We report a series of eight patients with adverse reactions to VCR over the course of 11 months at a single institution, four of which progressed to anaphylaxis and one of which resulted in cardiac arrest. Mass spectrometry analysis of medication lots was performed to test for possible contaminant(s). Our findings highlight the risk of anaphylaxis during therapy with VCR.