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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.

Supplementary Data from Statistical Considerations for Analyses of Time-To-Event Endpoints in Oncology Clinical Trials: Illustrations with CAR-T Immunotherapy Studies

Supplementary Figure from Comprehensive Serum Proteome Profiling of Cytokine Release Syndrome and Immune Effector Cell–Associated Neurotoxicity Syndrome Patients with B-Cell ALL Receiving CAR T19

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.

Supplementary Table from Statistical Considerations for Analyses of Time-To-Event Endpoints in Oncology Clinical Trials: Illustrations with CAR-T Immunotherapy Studies

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.

Supplementary Data from Comprehensive Serum Proteome Profiling of Cytokine Release Syndrome and Immune Effector Cell–Associated Neurotoxicity Syndrome Patients with B-Cell ALL Receiving CAR T19

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.

Unrelated donor (URD) hematopoietic stem cell transplant (HSCT) is associated with an increased risk of severe graft-versus-host disease (GVHD). TCRαβ/CD19 depletion may reduce this risk, whereas maintaining graft-versus-leukemia. Outcome data with TCRαβ/CD19 depletion generally describe haploidentical donors, with relatively few URDs. We hypothesized that TCRαβ/CD19-depletion would attenuate the risks of GVHD and relapse for URD HSCT. Sixty pediatric and young adult (YA) patients with hematologic malignancies who lacked a matched-related donor were enrolled at 2 large pediatric transplantation centers between October 2014 and September 2019. All patients with acute leukemia had minimal residual disease testing, and DP typing was available for 77%. All patients received myeloablative total body irradiation– or busulfan-based conditioning with no posttransplant immune suppression. Engraftment occurred in 98%. Four-year overall survival was 69% (95% confidence interval [CI], 52%-81%), and leukemia-free survival was 64% (95% CI, 48%-76%), with no difference between lymphoid and myeloid malignancies (P = .6297 and P = .5441, respectively). One patient (1.7%) experienced primary graft failure. Relapse occurred in 11 patients (3-year cumulative incidence, 21%; 95% CI, 11-34), and 8 patients (cumulative incidence, 15%; 95% CI, 6.7-26) experienced nonrelapse mortality. Grade III to IV acute GVHD was seen in 8 patients (13%), and 14 patients (26%) developed chronic GVHD, of which 6 (11%) had extensive disease. Nonpermissive DP mismatch was associated with higher likelihood of acute GVHD (odds ratio, 16.50; 95% CI, 1.67-163.42; P = .0166) but not with the development of chronic GVHD. URD TCRαβ/CD19-depleted peripheral HSCT is a safe and effective approach to transplantation for children/YAs with leukemia. This trial was registered at www.clinicaltrials.gov as #NCT02323867.

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.

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.

Summary 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.

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.

Despite impressive response to front-line treatment, relapsed or refractory B-cell acute lymphoblastic leukemia (r/r B-ALL) remains one of the most common causes of death in children with cancer. In pediatric and adult r/r B-ALL, CD19 CAR T cell (CART19) therapy has shown impressive results with over 80% of patients achieving complete remission. However, as an unintended consequence of long-term persistence of CAR T cells and the resulting sustained pressure against CD19 expressing cells, 30 - 70% of initial responders will eventually relapse with CD19 loss. Early identification of patients that will respond successfully to CART19 therapy vs. those at risk for CD19 Neg relapse would support clinical decision making and improve patient care. To address this problem, we profiled by mass cytometry (CyTOF) 25 pre-CART19 samples including patients that achieved a durable complete remission (CR, n = 6), patients that underwent CD19 Neg (n = 11) or CD19 Pos relapse (n = 4) and patients that were refractory to CART19 (n = 4). For 14 of those patients, we also analyzed paired post-CART19 samples: 8 from CD19 Neg relapse, 2 from CD19 Pos relapse, and 4 from refractory tumors. We observed a significant increase in the proportion of leukemic early progenitor non-B cells (called early-non-BI) after CD19 Neg relapse, suggesting that CD19 loss is associated with the loss of other B cell features. In addition, in the pre-CART19 samples we identified a subpopulation of CD19 Pos pro-B cells that resemble early-non-BI cells. We hypothesized that these pro-B "discordant" cells are able to lose CD19 expression and escape the immune pressure exerted by the CART19, leading to CD19 Neg relapse. Closer analysis revealed lower levels of IKAROS in pro-B discordant cells from patients that underwent CD19 Neg relapse, than in those that achieved a durable CR. To further explore the difference between pro-B discordant cells from patients that achieved a durable CR or underwent CD19 Neg relapse, we performed single cell REAP-seq (RNA expression and protein sequencing) from 3 pre-CART19 CR and 3 pre-CART19 CD19 Neg relapse r/r B-ALL samples. From this analysis, we confirmed a subpopulation of leukemic pro-B like cells with decreased expression of IKZF1 in those patients that underwent CD19 Neg relapse. IKAROS is a transcription factor that plays a crucial role in B cell lineage specification and commitment and is a known B-ALL tumor suppressor. Genetic alterations affecting the IKAROS gene, IKZF1, have been associated with poor response to front-line treatment and they are a factor in relapse risk stratification. However, a role for IKAROS in CART19 failure has not been described. To assess if there is a correlation between the levels of IKAROS and CD19 surface expression, we manipulated IKAROS levels in B-ALL cell lines through RNA silencing and targeted protein degradation approaches. Consistently, we observed that CD19 surface expression diminishes upon IKAROS downregulation. To determine how IKAROS regulates CD19 expression, we performed CyTOF, RNA-seq and ATAC-seq analysis of isogenic B-ALL cell lines with wild-type or reduced (IKAROS KD) IKAROS levels. While the chromatin accessibility to CD19 regulatory regions did not change, CD19 mRNA levels were lower in IKAROS KD cells. Interestingly, we found that IKAROS regulates several genes associated with mRNA splicing. In particular, CD19 mRNA preferentially retains intron 10 in IKAROS KD cells. The inclusion of intron 10 introduces several premature stop codons. Moreover, IKAROS KD B-ALL cells more closely resemble myeloid cells based on their gene expression profiles, suggesting a loss in their B cell identity. In summary, this is the first description of a leukemia-specific subpopulation of CD19 Pos pro-B discordant cells in patients prior CART19 administration. Furthermore, lower levels of IKAROS in this subpopulation correlates with poor response to CART19 therapy. Preliminary molecular analysis suggests that low IKAROS result in retention of CD19 intron 10 and loss of B-cell identity (Figure 1). Future research will focus on in-depth characterization of the myeloid-like phenotype induced by low levels of IKAROS expression, and the impact that intron 10 retention has on CD19 mRNA stability and surface expression. Figure 1 Figure 1. Disclosures Mullighan: Pfizer: Research Funding; Amgen: Current equity holder in publicly-traded company; Illumina: Membership on an entity's Board of Directors or advisory committees; AbbVie: 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. Barrett: Tmunity Therapeutics: Current Employment. Davis: Novartis Pharmaceuticals: Honoraria; Jazz Pharmaceuticals: Research Funding.

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.

Patient reported outcomes (PROs) are the gold standard for assessing patients' experience of treatment in oncology, defined in the 21st Century Cures Act as information about patients' experiences with a disease or condition, including the impact of a disease or condition, or a related therapy or clinical investigation on patients' lives; and patient preferences with respect to treatment of their disease or condition [1]. PROs provide a comprehensive assessment of the benefits and risks of new medical products, as well as essential data to inform real-world use. Although RCTs are the ultimate source for information for evaluating products in development, they are not always feasible for rare diseases with few or no effective treatment options available. Thus, it is important to consider other measures that can help to improve the strength of evidence for cell and gene therapies targeting rare indications. While collection of PROs and other patient experience endpoints does not resolve the difficulty of conducting trials in small populations, doing so contributes empirical evidence that informs both product development and patient access. Additionally, including routine collection of PROs in registries may provide supplemental data to further characterize the benefit:risk profile of cell and gene therapies at follow-up times that would be infeasible to operationalize in a clinical trial setting.

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: Chimeric Antigen Receptor T-cells targeting CD19 (CART-19) have shown promising efficacy for relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL). The ELIANA trial leading to market authorization of tisagenlecleucel excluded prior therapy with monoclonal antibodies. Blinatumomab prior to CART-19 seems associated with a higher risk of early failure (Pillai, Blood Advances 2019). Inotuzumab ozogamicin (InO) is an anti-CD22 antibody conjugated to calicheamicin. InO as bridging therapy to CART-19 (n=11) was associated with a shorter overall survival (OS) (Dourthe, Leukemia 2021). InO given prior to leukapheresis might impact on the quality of T-cells collected and, when used as bridging, could result in insufficient CD19 positive (CD19+) antigen load and affect CAR T-cell expansion. We report on a cohort of children and young adults with R/R BCP-ALL treated with InO prior to CART-19 infusion. Methods: Data of patients (pts) treated with CART-19 after InO given at any time before and/or after apheresis, irrespective of other anti-leukemic treatments, were collected using a standardized Case Report Form. The study was approved by the ethics committee of the UMC Utrecht (MvdL/is/21/500393) Results: Thirty-nine pts were treated in 10 centers and received CART-19 between July 2016 and April 2021. Thirty-four received commercial tisagenlecleucel and 5 academic products. Median age was 13 years (range 1-23); 25 were male. Four pts (10.3%) had received a prior CART-19 infusion and 15 (38%) blinatumomab, 18 (46%) had been previously transplanted. All pts received at least two doses of InO (range 2-12); 12 before apheresis only (median time 48 days (range 13-560) between last InO dose and apheresis); 27 as bridging therapy (median time 52 days (range 16-257) from last InO dose to CART-19 infusion), including 5 who had also received InO before apheresis. At time of the infusion, 22 pts were in complete remission (CR) ( At day 28 (d28) post infusion 35/39 were in CR (89.7%), of whom 31 (88.6%) were also MRD negative. Four pts (10.3%) did not achieve CR: 3/4 were not in CR at the time of the infusion; all of them received InO as bridging within 2 months before the infusion. With a median follow-up of 12.5 months (range 1-50) after CART-19 infusion, 12-month event free survival (EFS) was 59% (95% confidence interval (CI) [42.0-76.0]) and OS was 79.5% (95% CI [64.6-94.4]). There was no significant difference in OS/EFS between pts who received blinatumomab and InO prior to CART-19 infusion (n=15) and those who received InO only (n=24) (p=0.61 and p=0.37, respectively). Sixteen pts (45.7%) relapsed at median 163 days (range 28-655) after CART-19 infusion; 7/16 (43.8%) had a CD19+ relapse (median 287 days; range 28-655), 8/16 (50.0%) had a CD19 negative (CD19-) relapse (median 163 days; range 136-273) (1 status unknown). There was no significant difference in 12-month OS/EFS between pts who received InO before apheresis or as bridging (OS 83.3% vs 77.8%, p=0.50; EFS 58.3% vs 59.3%, p=0.62); and no difference in d28 MRD response (p=0.57) or incidence of CD19+ or CD19- relapses (p=0.48) between the 2 groups. Twelve of the 35 pts in CR at d28 (34.2%) lost BCA, median 92 days after CART-19 infusion (range 29−294) (1 data not available); 7/12 relapsed, 5/7 with CD19+ relapse. Among the 35 responders, 5/12 pts who received InO before harvesting lost BCA (1 data not available) vs 7/23 pts who received InO as bridging. There was no significant difference in 12-month EFS between pts who received CART-19 with low CD19 burden at start of lymphodepletion chemotherapy (MRD Conclusion: InO as a bridging strategy to CAR T-19 does not seem to result in inferior response when EFS/OS are compared to published data (Maude, NEJM 2018; Pasquini, Blood Adv, 2020). The ITCC/IntReALL-059 study will treat very high risk first relapsed BCP-ALL pts (very early relapse or presence of TP53 mutation and/or deletion, hypodiploidy, t(1;19)/t(17;19), KTM2A/AF4) with InO reinduction followed by CART, given the poor prognosis with current strategies. Disclosures O'Brien: Jazz: Honoraria; Pfizer: Honoraria, Research Funding. Jacoby: NOVARTIS: Honoraria, Membership on an entity's Board of Directors or advisory committees. Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharamceutical: Speakers Bureau; Takeda: Speakers Bureau. Zwaan: SANOFI: Consultancy; NOVARTIS: Consultancy; ROCHE: Consultancy; INCYTE: Consultancy; PFIZER: Consultancy, Research Funding; JAZZ: Other: travel funding, Research Funding; BMS: Research Funding; Abbvie: Research Funding.

Introduction: The most common severe toxicity associated with chimeric antigen receptor T-cells targeting CD19 (CART19) is cytokine release syndrome (CRS; PMID: 29972754). Our group and others have published seminal observations on the biology of CRS through cytokine profiling, measuring a small number of analytes (PMID: 27076371, 33434058). Multiple biomarkers including interferon gamma (IFNG), IL-6, and IL-10 have been associated with the development of severe CRS in previous studies (PMID: 33434058). To date, the only biomarker predictive of the development of CRS prior to infusion has been disease burden. To obtain a more robust understanding of CRS biology, we performed comprehensive secretome profiling to measure more than 1400 serum analytes on serial serum samples collected from patients treated with the 41BB-containing CTL019 on two clinical trials. Methods: Serum from patients enrolled on two clinical trials of the CART19 product CTL019 (NCT01626495 & NCT02906371) were obtained serially from pre-infusion to one month post infusion. Patients were categorised as having "minimal" (no CRS, Grade 1, or Grade 2) or "severe" (Grade 3 or 4) CRS. The serum secretome was profiled using the Olink Explore 1536 Analysis platform (Olink, Upsala, Sweden). 1484 proteins were measured from serum via proximity extension assay (PEA) high-multiplex immunoassay. Differential expression analysis, correlation analyses and receiver operating characteristic (ROC) calculations were performed using R (version 4.0.4) in RStudio. Significance was based on a fold change of greater than 2 or less than -2 and a false discovery rate of less than 0.05 calculated using a Benjamini-Hochberg correction. Results: 26 patients (10 NCT01626495 & 16 NCT02906371) were included comprising 128 unique datapoints from baseline to 35 days post-infusion. Thirteen patients had minimal and 13 had severe CRS. Differentially expressed proteins between minimal and severe CRS at the peak timepoint are shown in (A; green represents IFNG responsive proteins). Not surprisingly, proteins involved in IL-6 and IFNG signalling were increased, including biomarkers of hemophagocytic lymphohistiocytosis (HLH) such as VSIG4, CXCL9, CXCL10, CD163. The IL-18 signalling axis was dysregulated at peak CRS in severe patients with markedly elevated IL18 and IL18BP, despite prior reports suggesting IL-18 up-regulation is unique to the late CRS seen with CART22 (PMID: 32925169). Soluble markers of checkpoint inhibition, including soluble PDL1 (CD274) and LAG3 were also highly elevated. Finally, biomarkers of endothelial damage, such as PLAT, TMSB10 and CALCA were significantly elevated in patients with severe CRS. Pathway analysis revealed significant dysregulation in targetable cytokine, chemokine, and signalling pathways (B). A volcano plot of differentially expressed proteins at pre-infusion (C) identified a single protein, MILR1, as a candidate biomarker that was highly differentially expressed in patients who would subsequently develop severe CRS. MILR1 expression decreased over time (D). An ROC of MILR1 as a predictor for development of severe CRS (E) demonstrated pre-infusion elevated MILR1 could accurately predict development of severe CRS (sensitivity 88%, specificity 97%, AUC=0.977). We identified correlates of MILR1 at pre-infusion and found that MILR1 correlated most highly with soluble FLT3 (R=0.86, p Conclusions: With comprehensive secretome profiling we made multiple novel insights into the biology of CRS after CART19 and identified several potentially targetable proteins and pathways that could mitigate severe CRS. Similar secretome profiling in patients who developed neurotoxicity will also be shown. We identified two novel pre-infusion biomarkers that demonstrate significant capacity to predict the development of severe CRS following CART19 infusion. The inverse relationship apparent between FLT3 and FLT3LG that persists over time is an important finding that implies a potential biological role for FLT3/FLT3 ligand in the development of severe CRS. Mechanistic studies exploring the role of MILR1 and FLT3 in the initiation of CRS are ongoing. Figure 1 Figure 1. Disclosures Lambert: Novartis, shionogi, argenx, Rigel, octapharma: Consultancy; Rigel, Novartis, Sysmex, octapharma: Research Funding. Bassiri: Kriya Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company; Guidepoint Global: Consultancy. Levine: Vycellix: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Other: Co-Founder and equity holder; Ori Biotech: Membership on an entity's Board of Directors or advisory committees; Immusoft: Membership on an entity's Board of Directors or advisory committees; Immuneel: Membership on an entity's Board of Directors or advisory committees; Avectas: Membership on an entity's Board of Directors or advisory committees; Akron: Membership on an entity's Board of Directors or advisory committees; In8bio: Membership on an entity's Board of Directors or advisory committees. Maude: Wugen: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding. June: Tmunity, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Current equity holder in publicly-traded company; Novartis: Patents & Royalties; AC Immune, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Consultancy. Barrett: Tmunity Therapeutics: Current Employment. Grupp: Novartis, Kite, Vertex, and Servier: Research Funding; 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; Jazz Pharmaceuticals: Consultancy, Other: Steering committee, Research Funding. Teachey: Janssen: Consultancy; NeoImmune Tech: Research Funding; Sobi: Consultancy; BEAM Therapeutics: Consultancy, Research Funding.

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: CAR-modified T cells targeting CD19 have produced remarkable responses in relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL); however, relapse continues to be a substantial challenge. CD19+ relapses, which account for 33-78% of relapses, are associated with loss of CAR T-cell surveillance due to short persistence. Thus, strategies to improve functional persistence to prevent and treat CD19+ relapsed disease are crucial. Here, we report our experience administering reinfusions of murine or humanized 4-1BB CD19 CAR T cells in an effort to prolong persistence in patients with demonstrated short persistence to mitigate relapse risk, treat CD19+ relapsed disease, and produce responses after nonresponse to initial CAR infusion. Methods: This analysis included patients aged Results: Among 229 CAR-naïve and 33 CAR-exposed patients treated with CD19 CAR between 2012-2020, 81 received ≥1 reinfusion (investigational CTL019, n=44; commercial tisagenlecleucel, n=11; huCART19, n=13 CAR-naïve and n=13 CAR-exposed). In addition, 18 patients received PD-1 blockade after their first (n=11) or subsequent (n=7) reinfusions. Indications for first reinfusion were peripheral BCR (CAR-naïve, n=32; CAR-exposed, n=6), hematogones (CAR-naïve, n=21; CAR-exposed, n=4), CD19+ MRD/relapse (CAR-naïve, n=10, CAR-exposed, n=0), and nonresponse to initial infusion (CAR-naïve, n=5, CAR-exposed, n=3). CRS grade ≥2 (Penn scale) occurred in 19 patients (grade 2, n=13; grade 3, n=4; grade 4, n=2). Grade 3-4 events only occurred in patients with active disease at time of reinfusion. Twenty-two patients had an inpatient admission within 30 days of first reinfusion, of which 7 required intensive care unit admission Among the 63 patients reinfused for relapse prevention, 33 (52%) had a CR at day 28. With a median duration of follow-up of 38 mos, 13 experienced a subsequent relapse (7 CD19+, 4 CD19-, 2 CD19-subset negative), 4 received alternative therapy or allogeneic hematopoietic stem cell transplantation (HSCT) in remission, and 16 remain in remission without further therapy at a median of 39 mos after first reinfusion. The median duration of B-cell aplasia was 8 mos (IQR 2-35) after reinfusion. Of the 30 with no response (NR), 10 had a subsequent CD19+ relapse, 15 received alternative therapy or HSCT, and 5 remain in remission without further therapy at a median of 43 mos after reinfusion. CIR and OS were not statistically significantly different between patients with CR or NR (CIR, p=0.26; OS, p=0.25) (Figure A-B). However, at 24 mos after reinfusion, CIR was 29% (95% CI, 11-44%) for CR compared to 61% (95% CI, 24-80%) for NR; OS was 90% (95% CI, 80-100%) for both groups. Of the 10 patients reinfused for relapse, 5 (50%) had a CR; 2 subsequently experienced a CD19+ relapse, 2 received an HSCT in remission, and 1 remains in remission without further therapy at 18 mos after reinfusion. Of the 8 patients reinfused for nonresponse to initial infusion, 7 were evaluable; none had a CR, and all died at a median of 2.5 mos after reinfusion. Conclusions: Reinfusion of CTL019/tisagenlecleucel or huCART19 is safe, may prolong B-cell aplasia in patients with short CAR persistence and reduce relapse risk, and can induce remissions in patients with CD19+ relapsed disease. Thus, reinfusion may provide an alternative to HSCT for short persistence. However, reinfusion is not effective for patients with nonresponse to initial CAR infusion. Figure 1 Figure 1. Disclosures Callahan: Novartis: Speakers Bureau. Rheingold: Optinose: Other: Spouse's current employment; Pfizer: Research Funding. June: Tmunity, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Current equity holder in publicly-traded company; Novartis: Patents & Royalties; AC Immune, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Consultancy. 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: Novartis Pharmaceuticals Corporation: Consultancy, Research Funding; Wugen: Consultancy.

Background CART19-related toxicities may require treatment inpatient or in the ICU. We sought to describe inpatient/ICU resource utilization within 30 days of CART19 infusion and evaluate trends in resource utilization from 2012-2019. Methods We identified patients (pts) with ALL treated with CART19 on a clinical trial (NCT01626495, NCT02906371, and NCT02374333) or with the commercial product, tisagenlecleucel, at Children's Hospital of Philadelphia. Demographic, pharmacy, and inpatient data were extracted from the EHR from day of infusion (d0) to d+30 using a semi-automated EPIC data query tool. The Virtual Pediatric Systems database was queried for resource utilization data and PRISM 3 and PIM 2 severity of illness scores. Log-binomial and linear regression were used to estimate the association of patient characteristics with inpatient/ICU admission and inpatient/ICU length of stay (LOS). Similar models were used to estimate trends over time. Results The analyses included 213 pts. Median age was 12y (range 1-29y); 60% were male. Prior to CART19, 42% had an alloHCT. Pre-infusion, 19% had high tumor burden (HTB), defined as bone marrow blasts ≥40%. From 2012-2019, the proportion of pts with prior alloHCT or HTB decreased (Table 1). CART19 was infused in the outpatient setting in 198 (93%) pts. From d0 to d+30, 149 (70%) had ≥1 inpatient admission, starting at a median of d+2 (IQR +1 to +6). Among admitted pts, median cumulative inpatient LOS was 7d (IQR 4-13). From 2012-2019, there were linear trends toward decreases in proportion of pts admitted (p ICU admission was required for 49 (23%) pts, starting at a median of day +5 (IQR +4 to +7). ICU admission was more frequent for pts with HTB [HTB, 68% (95% CI, 52-81) vs. low burden, 11% (95% CI, 7-17), p Other than HTB, baseline characteristics were not associated with inpatient/ICU admission or LOS. Conclusion In a cohort of 213 pediatric pts, over 90% were safely infused with CART19 in the outpatient setting. Though 70% required at least one admission, the proportion of pts admitted to the hospital or ICU and cumulative inpatient LOS decreased over the past 7 years.

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 Patients (pts) receiving CTL019 (tisagenlecleucel) for B-ALL with high tumor burden (HTB) are at high risk for developing severe CRS. Tocilizumab, an IL-6 receptor antibody, is a vital component of severe CRS management; however, its role in preventing severe CRS is not known. We sought to determine the effectiveness of preemptive tocilizumab (PT) administration in decreasing the rate of grade (gr) 4 CRS in HTB pts. Methods We conducted a pilot trial of risk-adapted PT after CTL019 (NCT02906371). HTB pts, defined as ≥40% bone marrow (BM) blasts immediately before infusion, received a single dose of PT for high persistent fever (2 temperatures ≥38.5C in 24hr). The primary endpoint was frequency of gr4 CRS (Penn scale), with an observed rate of ≤5/15 predefined as clinically meaningful. Secondary endpoints included complete remission (CR) rate and ICU length of stay (LOS). A comparator cohort with HTB who received standard CRS management (stdCRS) was identified from the initial CTL019 trial (NCT01626495). Results Characteristics of the PT (n=15) and stdCRS (n=26) HTB cohorts are shown in Table 1. All pts developed gr≥2 CRS; median time to fever was longer in the PT cohort [PT, 3d (IQR 2-9); stdCRS, 2d (IQR 1-7), p=0.03]. Gr4 CRS was observed in 4/15 (27%) pts in the PT cohort vs. 13/26 (50%) in the prior stdCRS cohort [RR 0.53 (95% CI, 0.21-1.34), p=0.18]. In the stdCRS cohort, gr4 CRS was associated with earlier onset of fever (p=0.04). In patients with earlier CRS onset (fever by day +4), gr4 CRS was observed in 4/9 (44%) vs. 13/21 (62%) in the PT and stdCRS cohorts [RR 0.72 (95% CI, 0.32-1.60), p=0.42]. Except for a trend toward fewer vasoactive days in the PT cohort, ICU LOS and resource utilization were not significantly different (Table 2). The CR rate at day 28 was similar in the PT and stdCRS cohorts (87% vs. 85%, p=1.00). Conclusion Risk-adapted PT administration reduced gr4 CRS, meeting the predefined study endpoint, without impacting the CR rate. A secondary comparison to a prior trial showed a clinically meaningful decrease in the rate of gr4 CRS from 50% to 27%; however, the analysis was not powered to detect a statistically significant difference. Ongoing analyses will evaluate CAR T cell expansion, duration of remission, and additional safety endpoints, including rates of neurotoxicity.

Most acute minor and moderate illness episodes unfold as a linear journey, from health to illness, and, one hopes, back again. In this simplest of illness models, outcomes exist along a single dimension, such as the length of illness or the probability of full recovery. As illness becomes more chronic or severe, the corresponding model of illness becomes more complicated as the dimensions of outcomes increases. Length of time away from normal activities or in the hospital, along with the probability of complications or survival, provide different views of outcomes. When the subjective aspects of the illness experience, such as symptom distress or quality of life, are incorporated into the illness model, the dimensionality of the model rises substantially. All of which is to say that just as a stick figure is not an accurate drawing of an individual human, the simple model of illness is not an accurate rendition of the real multidimensional disorder. Nevertheless, the simple model can be extraordinarily useful. Medical science progresses by working with tractable models of health and disease. For this … Address correspondence to Allison Barz Leahy, MD, Cellular Therapy Program, Division of Oncology, Children’s Hospital of Philadelphia, 3501 Civic Center Blvd, Philadelphia, PA 19104. E-mail: barza{at}email.chop.edu

Symptom monitoring using patient-reported outcomes (PROs) is not common in pediatric oncology, despite interest from stakeholders, including patients, families, clinicians, and regulatory organizations as well as proven clinical benefit in adult oncology. This article examines the foundational data for patient-reported symptom reporting in this population and posits the next investigative steps toward the implementation of patient-reported symptom monitoring in the care and research of pediatric oncology patients. The reasoning behind and feasibility of monitoring symptoms in pediatric oncology patients using PRO measures is discussed, as well as specific tools that have been developed to track symptoms in this population, including innovative, electronic self-reporting platforms built to engage children in the symptom reporting process. Aspects of engaging both patients and clinicians in the symptom self-report process are reviewed, as are the experiences of “early adopters” of this process in pediatric oncology and across pediatrics. It is clear that there are key issues that remain regarding the use of PROs for symptom monitoring, including selection of specific outcomes to monitor, how to resolve discrepant reports, and determination of benefit. Next steps for investigation of these issues are discussed. Unanswered questions notwithstanding, work should continue to make patient-reported symptom monitoring an established, evidence-based part of routine and research practice in pediatric oncology.

Background: CTL019 is a therapy derived from autologous T cells expressing a CD19-specific chimeric antigen receptor (CAR) that was approved by the FDA in August 2017 (tisagenlecleucel). Complete and durable remissions have been seen in the setting of pediatric and young adult patients with relapsed and refractory B cell acute lymphoblastic leukemia (ALL) (Maude NEJM 2018). Initial case reports suggested that there may be differential outcomes mediated by cytogenetic characteristics of the leukemia at CAR T cell infusion. Here, we report results from a single institution experience of 112 patients. Methods: Patients with relapsed/refractory ALL were identified as having received CTL019 either in the context of a clinical trial (NCT02906371) or commercial product (tisagenlecleucel) at Children's Hospital of Philadelphia from October 2016 to April 2019. Patients who received prior CAR T therapy were excluded. Demographic, cytogenetic, and outcome data were manually abstracted from the medical record or clinical trial datasets. High risk lesions were defined as MLL(KMT2A) rearrangements, Philadelphia-chromosome (Ph+), Ph-like, hypodiploidy, and TCF3/HLF fusion. Favorable cytogenetics were defined as the presence of hyperdiploidy or ETV6/RUNX1fusion and intermediate were defined as iAMP21, IKZF1deletion, or TCF3/PBX1. Patients were classified according to their highest risk cytogenetic characteristic and stratified by cytogenetic risk category present at CAR T cell infusion. Relapse-free survival (RFS) and overall survival (OS) was described for cohorts with more than 10 patients. Results: One hundred and twelve patients were included in the analysis, with a median age of 11 years (range 1-29) at infusion, of which 32% had had a previous allogeneic hematopoietic stem cell transplant (alloHSCT). Disease burden at the time of CTL019 infusion was heterogenous, with 61% having detectable disease in the bone marrow and 21% having more than 25% blasts by flow cytometry. Thirty-six patients (32%) had leukemias with high-risk genetic lesions at infusion, including 12 with MLL rearrangements and 18 with Ph+ or Ph-like lesions (Table 2). Thirty-one patients (28%) had hyperdiploidy or ETV6/RUNX1; 3 additional were in conjunction with high-risk cytogenetics (t(17;19) and 2 with Ph+), and 3 in the setting of intermediate-risk cytogenetics (iAmp21, TCF3/PBX1, IKZF1deletion). Figure 1 demonstrates RFS for those patients in remission at day 28 following infusion, stratified by cytogenetic risk category. Complete remission (CR) rate in the high-risk cytogenetics group was 94%. RFS at 12 months was 69% (0.50-0.82), 69% (0.40-0.86), and 67% (0.48-0.80) for non-informative, favorable, and high-risk cytogenetic groups, respectively. Figure 2 shows OS of patients infused with CTL019, again stratified by cytogenetic categories of interest, with a maximum follow-up time of 30 months. OS at 12 months was 84% (0.68-0.93) and 76% (0.56-0.88) for the non-informative and high-risk cytogenetic groups, respectively. There were no deaths in that time period for the favorable risk category. There was no statistically significant difference in RFS or OS for patients with high-risk cytogenetics. The intermediate-risk cytogenetics group (n Conclusion: Durable remissions can be achieved with CTL019 across several high-risk cytogenetic subtypes of B-ALL. Stratifying outcomes by cytogenetic risk category in this unadjusted analysis does not show a statistically significant difference in either RFS nor OS. Further investigation is needed to parse out the contribution of individual cytogenetic lesions as well as the effects of other relapse and survival risk factors at play. Figure Disclosures Rheingold: Novartis: Consultancy; Pfizer: Research Funding. Callahan:Novartis: Consultancy. Hunger:Bristol Myers Squibb: Consultancy; Amgen: Consultancy, Equity Ownership; Jazz: Honoraria; Novartis: Consultancy. Grupp:Novartis: Consultancy, Research Funding; Roche: Consultancy; GSK: Consultancy; Cure Genetics: Consultancy; Humanigen: Consultancy; CBMG: Consultancy; Novartis: Research Funding; Kite: Research Funding; Servier: Research Funding; Jazz: Other: study steering committees or scientific advisory boards; Adaptimmune: Other: study steering committees or scientific advisory boards. Maude:Kite: Consultancy; Novartis: Consultancy.

Background: CD19-targeted chimeric antigen receptor T cell therapy (CART19) has demonstrated remarkable clinical efficacy in treating relapsed/refractory B cell ALL, but associated toxicities may require treatment in inpatient or intensive care units (ICU). We sought to: (1) describe inpatient and ICU resource utilization within 30 days of CART19 infusion; and (2) evaluate trends in resource utilization from 2012-2019. Methods: We identified patients treated with CART19 on a clinical trial (NCT01626495, NCT02906371, and NCT02374333) or with the commercial product, tisagenlecleucel, at Children's Hospital of Philadelphia. Patients who received a prior cell therapy product were excluded. Demographic, pharmacy, and inpatient data were extracted from the electronic medical record from day of infusion (day 0) to day +30, censored at disease progression or death, using a semi-automated EPIC data query tool (ExtractEHR). The Virtual Pediatric Systems (VPS) database was queried for clinical data, resource utilization data, and Pediatric Risk of Mortality (PRISM) 3 and Pediatric Index of Mortality (PIM) 2 severity of illness scores. Log-binomial regression and linear regression were used to estimate the association of patient characteristics with the need for inpatient/ICU admission and inpatient/ICU length of stay (LOS), respectively. Similar models were used to estimate trends in outcomes from 2012-2019. Results: A total of 213 patients were included in the analyses. Median patient age was 12.4 years (range 1.4-29.1) at infusion; 60% were male, 66% were Caucasian, and 80% were non-Hispanic. Prior to CART19, 42% had an allogeneic hematopoietic cell transplant (alloHCT). At time of infusion, 19% had high disease burden, defined as bone marrow blasts ≥40% by flow cytometry. From 2012-2019, the proportion of patients with prior alloHCT or high disease burden decreased (Table 1). CART19 was infused in the outpatient setting in 93% of patients. In the 30 days after infusion, 70% had at least one inpatient admission, starting at a median of day +2 (IQR +1 to +6). Among the 149 patients admitted, median cumulative inpatient LOS was 7 days (IQR 4-13). Cumulative LOS increased with increasing grade of cytokine release syndrome (CRS). Median LOS was 0, 5, and 15 days for patients with no, mild, and severe CRS, respectively. From 2012-2019, there were linear trends toward decreases in proportion of patients admitted (p ICU admission was required for 23% (95% CI, 17-29) of the cohort, starting at a median of day +5 (IQR +4 to +6.5). ICU admission was more frequent for patients with high disease burden than those with low disease burden [68% (95% CI, 52-81) vs. 11% (95% CI, 7-17), p Other than high disease burden, baseline patient characteristics were not significantly associated with inpatient/ICU admission or inpatient/ICU LOS. Conclusion: In a cohort of 213 pediatric patients with ALL who received CART19, over 90% were safely infused in the outpatient setting. Though the majority of patients required at least one inpatient admission, the proportion of patients admitted to the hospital or ICU and cumulative inpatient LOS in the 30 days post-infusion decreased over the past 7 years. Mortality was 1%. Additional analyses will investigate the impact of changes in supportive care practices on resource utilization outcomes. Disclosures Grupp: GSK: Consultancy; Cure Genetics: Consultancy; Humanigen: Consultancy; CBMG: Consultancy; Novartis: Research Funding; Kite: Research Funding; Novartis: Consultancy, Research Funding; Roche: Consultancy; Servier: Research Funding; Jazz: Other: study steering committees or scientific advisory boards; Adaptimmune: Other: study steering committees or scientific advisory boards. Maude:Novartis: Consultancy; Kite: Consultancy.

Background: Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and requires intensive and prolonged chemotherapy. There are limited published data describing the number and characteristics of admissions to the hospital following initial diagnosis. This study aimed to describe the number and timing of admissions in children with ALL at hospitals across the United States. Admissions were categorized as expected or unexpected to provide a more comprehensive understanding of the hospitalization patterns for children with ALL. Methods: A retrospective cohort study was designed using the Pediatric Health Information System (PHIS) database. PHIS, an administrative database that includes inpatient data from over 45 freestanding children's hospitals, contains demographic information, dates of admission and discharge, length of stay (LOS), discharge diagnosis and procedure codes, as well as billing encounters for medications. A cohort of pediatric patients with newly diagnosed ALL was previously identified using ICD-9 discharge diagnosis codes and chemotherapy exposure data. Patients were classified as high risk (HR) if billing data suggested receipt of an anthracycline within the first month of chemotherapy, otherwise patients were considered standard risk (SR). Admission patterns were explored by risk classification, age group, gender, race and ethnicity. Each admission was assessed for utilization of chemotherapy agents or parenteral antibiotics in the first two hospital days. Based on these resource utilization data admissions were hierarchically categorized as "chemotherapy related", "infection related", or "neither chemotherapy nor infection related". The former two categories were considered expected admissions while the third was considered unexpected. Each admission was also classified by the presence of billing codes for resources consistent with intensive care unit (ICU) level of care. Patient follow-up was censored at time of inpatient death or the projected end of treatment (28 months for females, 40 for males). Results: The majority of pediatric ALL patients (94.9% of HR, 87.5% of SR) had one or more admission after diagnosis. HR patients had a median of 7 admissions (range 0-43), with a 5-day median LOS (range 1-414) and median total of 55 hospitalized days (range 1-728). In contrast, SR patients had a median of 3 admissions (range 0-31), with a 4-day LOS (range 1-352) and 24 total hospitalized days (range 1-453). The distribution of admissions was skewed toward the first 6-months after diagnosis (Figure 1). Limited variability in number, duration, and timing of admissions was seen when stratifying by sex, race, or ethnicity. Of all admissions following diagnosis admission, 26.5% were chemotherapy-related, 49.1% were infection-related, and 24.3% were unexpected admissions. HR patients had a median of 1 chemotherapy-related admission (range 0-23), 3 infection-related admissions (range 0-26), and 1 unexpected admission (range 0-22). In SR patients there were 0 (range 0-21), 2 (0-20), and 1 (0-22), respectively. Children with infant leukemia (diagnosed The need for ICU level of care within an admission was common; 18.7% of HR patients had at least 1 admission that required ICU care, 4.1% had 2 or more. In SR patients, 5.3% had at least 1 admission that required ICU care, 0.4% had 2 or more such admissions. Conclusion: This study is the first step in benchmarking typical admission rates and characteristics after the index diagnosis admission. Patients who receive anthracyclines at diagnosis experience more frequent admissions early after diagnosis and admissions are more likely to be of higher acuity. Unexpected admissions were present in both groups, and account for nearly a quarter of all hospitalizations after diagnosis. It is imperative that we determine the etiology and risk factors associated with these unexpected admissions in order to identify potentially avoidable inpatient stays. Understanding predictive factors can inform the development of interventions to reduce avoidable admissions and to mitigate associated human and financial costs. Disclosures Fisher: Merck: Research Funding; Pfizer: Research Funding.

Background: Online patient and caregiver self-reporting for symptom and toxicity monitoring during chemotherapy can inform proactive clinical management and ameliorate serious adverse events. In adults, patient-reported symptom monitoring during chemotherapy improves quality of life, decreases hospitalizations, and lengthens survival. The feasibility of this approach in pediatrics has not been established. This study assesses the implementation of daily electronic patient-reported symptom monitoring for pediatric oncology patients hospitalized for chemotherapy. Methods: The Common Terminology Criteria for Adverse Events (CTCAE) is used to grade adverse events in cancer trials. The Pediatric PRO-CTCAE is a questionnaire for children to self-report symptoms while undergoing cancer treatment. The study population was patients 7-18 years of age, English-literate, with a planned admission for chemotherapy expected to last 48 hours at a single tertiary care pediatric institution. Patients and caregivers were asked to respond daily, following text or email prompts, to Pediatric PRO-CTCAE questions addressing ten symptoms via REDCap (web-based data capture). Each morning, completed symptom reports were emailed to the frontline clinicians. No instructions were given regarding the use of patient-reported information. Utilization of symptom reports was determined by electronic survey administered to the same clinician several hours following receipt of the report. Provider acceptability was assessed monthly. Patient and caregiver satisfaction was evaluated after discharge. Results: Fifty-five patients and their caregivers were invited to participate and 45 patient/caregiver dyads enrolled (82%). Chemotherapy regimens included those for leukemia/lymphoma (40%), bone marrow transplant (BMT, 11%), solid tumor (36%) and neuro-oncology (13%). Mean patient age was 12.8 years (range 7-18). Mean length of hospitalization was 8.5 days (median 4, range 2-42). Approximately half the evaluable dyads (48.8%) generated at least one symptom report (patient or caregiver) daily; three-quarters (75.6%) submitted symptom reports at least half of all hospitalized days. When stratified to include only leukemia/lymphoma and BMT patients, mean length of stay was 13.8 days (median 6, range 2-42), and proportions of daily symptom report submissions were comparable to the overall cohort. However, all dyads with leukemia/lymphoma or BMT completed at least one symptom report following enrollment, compared to four dyads among the group with neuro-oncology or solid tumor diagnoses that submitted no symptom reports following enrollment. In response to the individual symptom reports (217 from 37 dyads) clinicians reported that clinical actions were taken 25% of the time, including counseling the use of medications already prescribed (43), prescribing a new medication or altering dosage of a currently prescribed medication (22), performing laboratory tests (1) or imaging (3), and obtaining a consult from another service or team (4). All participating healthcare providers (n=42) understood the symptom reports, and all, except one, found the reports useful and expressed interest in continuing to receive them. A quarter of providers reported that reviewing the symptom reports enhanced communication with the patient or family. Patients and caregivers found the questions easy to understand and the system easy to use. Half of the patients (51.7%) reported that submitting symptom reports helped them "a lot" or "completely" to have conversations with their doctors, and most (82.8%) expressed interest in continuing to provide symptom reports after study participation ended. Fewer caregivers (34.4%) endorsed that submitting symptom reports helped them to have conversations with the patient's doctor, but 50% noted that they helped "a lot" or "completely" to keep track of their child's health and to feel more connected to the healthcare team. Conclusion: Patient and caregiver symptom self-reporting is a feasible and acceptable strategy for symptom monitoring in pediatric patients hospitalized for chemotherapy. Patients and their caregivers find this method of symptom reporting beneficial. Further, healthcare providers find the information useful and influential in medical decision-making. Larger scale studies are needed to further assess implementation and impact of symptom monitoring. Disclosures No relevant conflicts of interest to declare.

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.