Abstract-Background:Pompe disease is a progressive metabolic neuromuscular disorder resulting from deficiency of lysosomal acid ␣-glucosidase (GAA). Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death. The safety and efficacy of recombinant human (rh) GAA were evaluated in 18 patients with rapidly progressing infantile-onset Pompe disease. Methods: Patients were diagnosed at 6 months of age and younger and exhibited severe GAA deficiency and cardiomyopathy. Patients received IV infusions of rhGAA at 20 mg/kg (n ϭ 9) or 40 mg/kg (n ϭ 9) every other week. Analyses were performed 52 weeks after the last patient was randomized to treatment. Results: All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group. There was no clear advantage of the 40-mg/kg dose with regard to efficacy. Eleven of the 18 patients experienced 164 infusion-associated reactions; all were mild or moderate in intensity. Conclusions: Recombinant human acid ␣-glucosidase is safe and effective for treatment of infantile-onset Pompe disease. Eleven patients experienced adverse events related to treatment, but none discontinued. The young age at which these patients initiated therapy may have contributed to their improved response compared to previous trials with recombinant human acid ␣-glucosidase in which patients were older.

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

Tisagenlecleucel is a chimeric antigen receptor–T cell therapy that facilitates the killing of CD19 + B cells. A model was developed for the kinetics of tisagenlecleucel and the impact of therapies for treating cytokine release syndrome (tocilizumab and corticosteroids) on expansion. Data from two phase II studies in pediatric and young adult relapsed/refractory B cell acute lymphoblastic leukemia were pooled to evaluate this model and evaluate extrinsic and intrinsic factors that may impact the extent of tisagenlecleucel expansion. The doubling time, initial decline half‐life, and terminal half‐life for tisagenlecleucel were 0.78, 4.3, and 220 days, respectively. No impact of tocilizumab or corticosteroids on the expansion rate was observed. This work represents the first mixed‐effect model‐based analysis of chimeric antigen receptor–T cell therapy and may be clinically impactful as future studies examine prophylactic interventions in patients at risk of higher grade cytokine release syndrome and the effects of these interventions on chimeric antigen receptor–T cell expansion.

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In the statistics section, the equation to generate a final prediction model from the training set was incorrect. The correct sentence is below. We then created a training set at random and repeated the entire process to generate a final model: log[-log(1-p̂)] =-11.263 + 1.844(log10ST2) + 0.577(log10REG3α), where p̂ = predicted probability of 6-month NRM.

Salvage treatment with chemotherapy before DLI can help some patients with advanced myeloid relapse and is not dependent on GVHD. Patients with short remissions after BMT are unlikely to benefit from this approach, and the approach is associated with significant treatment-related mortality. Modifications of this approach or entirely different approaches will be required for most patients with this difficult clinical problem.

Background: CTL019 is an investigational therapy derived from autologous T-cells expressing a CD19-specific chimeric antigen receptor (CAR). A single center, phase I/IIa trial of CTL019 showed complete and durable remissions in pediatric/young adult patients (pts) with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) (Maude et al NEJM 2014); these results have yet to be reproduced in a multicenter setting. Here, we report results from a 6-month interim analysis of the first multicenter phase II trial of an engineered cell therapy in leukemia. Methods: 9 US sites participated in this single-arm phase II study in pediatric/young adult pts with R/R B-ALL. Leukapheresis products were shipped for centralized manufacturing according to the University of Pennsylvania (Penn) process in an academic-industry collaboration. T cells were transduced with a lentiviral vector encoding a CAR composed of anti-CD19 scFv, CD3ζ and 4-1BB domains. Following lymphodepletion with fludarabine and cyclophosphamide, a single dose of CTL019 cells was administered (target dose 2.0-5.0×106 cells/kg for ≤50 kg and 1.0-2.5×108 cells for >50 kg). The primary endpoint was overall remission rate (ORR = CR + CRi [CRi, complete remission with incomplete blood count recovery] maintained at 2 evaluations ≥28 days apart) as determined by an Independent Review Committee. Secondary objectives included minimal residual disease (MRD), relapse-free survival (RFS), overall survival (OS) and safety. All analyses were performed on infused patient set. Results: 29/35 pts enrolled (82.9%) were infused with CTL019; 6 withdrew prior to infusion (2 manufacturing failures [1 lack of growth, 1 contamination]; 4 deaths [median, 48 days from enrollment; 2 progressive disease, 1 multi-organ failure, 1 pneumonia]). Mean bone marrow involvement at enrollment was 68.2% (SD, 27.3%; Table 1). 2 pts did not receive lymphodepleting chemotherapy due to leukopenia. Collection, manufacturing and infusion were feasible in a multicenter setting with a median time from enrollment to infusion of 37 days. Target cell dose was met in 24/33 (72.7%) manufactured products. ORR in all infused pts was 69.0% (20/29 pts; 98.95% CI 43.6, 88.1). Of the 5 pts who received CTL019 below the target dose, 2 achieved CR/CRi. Of note, deep remission with no evidence of MRD (<0.01%) was achieved in 18/29 pts (62.1%; 95% CI 42.3, 79.3) within 6 months. Median RFS and median survival have not yet been reached. Median duration of follow-up was 6.4 months (range 0.4-14.0). CR/CRi was not achieved in 9 pts: 2 pts died before Day 28 (1 ALL; 1 embolic stroke not attributed to CTL019 at Day 25 after infusion), 6 did not respond and 1 pt achieved CRi at Day 28 but relapsed 17 days later. Of the 20 pts who achieved a CR/CRi, 8 pts relapsed 1.7-7.6 months after onset of remission; 2 were CD19 negative. RFS and OS at 6 months (Figures 1, 2) were 66.4% and 75.7%, respectively. Serious adverse events occurred in 79.3% of pts within 8 weeks of infusion. Overall 10 deaths occurred at 0.4-8.8 months (9 ALL; 1 embolic stroke); no deaths attributable to CTL019. The most common adverse event was cytokine release syndrome (CRS), which was graded on the Penn scale and managed according to a standardized algorithm. All 26 (89.7%) cases of CRS were reversible; 11 pts (37.9%) had grade 3 or 4 CRS, of which 7 (26.9%) required systemic anti-cytokine therapy, 9 (34.6%) required high dose vasopressors for hypotension, 6 (23.1%) required mechanical ventilation, 4 (15.4%) underwent dialysis. Reversible neuropsychiatric events occurred in 9 (31%) pts (1 grade 3; no grade 4), including seizures in 2 pts but no cases of cerebral edema. Conclusions: In this first multicenter trial of CAR-modified T cell therapy, CTL019 therapy was feasible and efficacious, showing a high ORR with durable remissions in pediatric/young adult pts with R/R B-ALL. Despite the high rate of toxicity with CTL019 in the R/R setting, the rate of grade 3 or 4 CRS was comparable to the single center study, and standardized management of CRS was successful in a multicenter trial with no deaths attributable to CRS. In this highly refractory population, a vast majority of eligible pts can be successfully infused in a timely fashion and outcomes appear reproducible in a multicenter setting despite a more heterogeneous population than the single center study. The trial is continuing under Novartis manufacturing. Disclosures Maude: Novartis: Consultancy. Pulsipher:Medac: Other: Travel support for a study group; Chimerix: Consultancy, Other: Advisory Board ; Jazz Pharmaceutical: Consultancy, Other: Advisory Board; Novartis: Consultancy, Other: Advisory Board, Steering Committee for Phase II Study. Grupp:Pfizer: Consultancy; Novartis: Consultancy, Research Funding. Davies:Novartis: Honoraria. Verneris:Bimogen: Other: Advisory Board. Schlis:Novartis: Honoraria. Driscoll:Novartis: Consultancy. June:Immune Design: Consultancy, Equity Ownership; Pfizer: Honoraria; Celldex: Consultancy, Equity Ownership; Novartis: Honoraria, Patents & Royalties, Research Funding; Johnson & Johnson: Honoraria; Novartis: Honoraria, Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership. Levine:GE Healthcare Bio-Sciences: Consultancy; Novartis: Patents & Royalties, Research Funding. Wood:Novartis Pharmaceuticals: Employment, Other: Stock. Yi:Novartis: Employment.

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