Tracey A. O’Brien

Analysis of risk factors influencing outcomes after cord blood transplantation in children with juvenile myelomonocytic leukemia: a EUROCORD, EBMT, EWOG-MDS, CIBMTR study

We retrospectively analyzed 110 patients with juvenile myelomonocytic leukemia, given single-unit, unrelated donor umbilical cord blood transplantation. Median age at diagnosis and at transplantation was 1.4 years (age range, 0.1-6.4 years) and 2.2 years (age range, 0.5-7.4 years), respectively. Before transplantation, 88 patients received chemotherapy; splenectomy was performed in 24 patients. Monosomy of chromosome 7 was the most frequent cytogenetic abnormality, found in 24% of patients. All but 8 patients received myeloablative conditioning; cyclosporine plus steroids was the most common graft-versus-host disease prophylaxis. Sixteen percent of units were HLA-matched with the recipient, whereas 43% and 35% had either 1 or 2 to 3 HLA disparities, respectively. The median number of nucleated cells infused was 7.1 × 10(7)/kg (range, 1.7-27.6 × 10(7)/kg). With a median follow-up of 64 months (range, 14-174 months), the 5-year cumulative incidences of transplantation-related mortality and relapse were 22% and 33%, respectively. The 5-year disease-free survival rate was 44%. In multivariate analysis, factors predicting better disease-free survival were age younger than 1.4 years at diagnosis (hazard ratio [HR], 0.42; P = .005), 0 to 1 HLA disparities in the donor/recipient pair (HR, 0.4; P = .009), and karyotype other than monosomy 7 (HR, 0.5; P = .02). Umbilical cord blood transplantation may cure a relevant proportion of children with juvenile myelomonocytic leukemia. Because disease recurrence remains the major cause of treatment failure, strategies to reduce incidence of relapse are warranted.

Long-Term Survival and Late Deaths after Hematopoietic Cell Transplantation for Primary Immunodeficiency Diseases and Inborn Errors of Metabolism

It is uncertain whether late mortality rates after hematopoietic cell transplantation for severe combined immunodeficiency (SCID), non-SCID primary immunodeficiency diseases (non-SCID PIDD), and inborn errors of metabolism (IEM) return to rates observed in the general population, matched for age, sex, and nationality. We studied patients with SCID (n = 201), non-SCID PIDD (n = 405), and IEM (n = 348) who survived for at least 2 years after transplantation with normal T cell function (SCID) or >95% donor chimerism (non-SCID PIDD and IEM). Importantly, mortality rate was significantly higher in these patients compared with the general population for several years after transplantation. The rate decreased toward the normal rate in patients with SCID and non-SCID PIDD beyond 6 years after transplantation, but not in patients with IEM. Active chronic graft-versus-host disease at 2 years was associated with increased risk of late mortality for all diseases (hazard ratio [HR], 1.87; P = .05). In addition, late mortality was higher in patients with non-SCID PIDD who received T cell-depleted grafts (HR 4.16; P = .007) and in patients with IEM who received unrelated donor grafts (HR, 2.72; P = .03) or mismatched related donor grafts (HR, 3.76; P = .01). The finding of higher mortality rates in these long-term survivors for many years after transplantation confirms the need for long-term surveillance.

Engraftment kinetics and graft failure after single umbilical cord blood transplantation using a myeloablative conditioning regimen

Umbilical cord blood transplant recipients are exposed to an increased risk of graft failure, a complication leading to a higher rate of transplant-related mortality. The decision and timing to offer a second transplant after graft failure is challenging. With the aim of addressing this issue, we analyzed engraftment kinetics and outcomes of 1268 patients (73% children) with acute leukemia (64% acute lymphoblastic leukemia, 36% acute myeloid leukemia) in remission who underwent single-unit umbilical cord blood transplantation after a myeloablative conditioning regimen. The median follow-up was 31 months. The overall survival rate at 3 years was 47%; the 100-day cumulative incidence of transplant-related mortality was 16%. Longer time to engraftment was associated with increased transplant-related mortality and shorter overall survival. The cumulative incidence of neutrophil engraftment at day 60 was 86%, while the median time to achieve engraftment was 24 days. Probability density analysis showed that the likelihood of engraftment after umbilical cord blood transplantation increased after day 10, peaked on day 21 and slowly decreased to 21% by day 31. Beyond day 31, the probability of engraftment dropped rapidly, and the residual probability of engrafting after day 42 was 5%. Graft failure was reported in 166 patients, and 66 of them received a second graft (allogeneic, n=45). Rescue actions, such as the search for another graft, should be considered starting after day 21. A diagnosis of graft failure can be established in patients who have not achieved neutrophil recovery by day 42. Moreover, subsequent transplants should not be postponed after day 42.

A Population-Based Cohort Study of Late Mortality in Adult Autologous Hematopoietic Stem Cell Transplant Recipients in Australia

We assessed overall and cause-specific mortality and risk factors for late mortality in a nation-wide population-based cohort of 4547 adult cancer patients who survived 2 or more years after receiving an autologous hematopoietic stem cell transplantation (HSCT) in Australia between 1992 and 2005. Deaths after HSCT were identified from the Australasian Bone Marrow Transplant Recipient Registry and through data linkage with the National Death Index. Overall, the survival probability was 56% at 10 years from HSCT, ranging from 34% for patients with multiple myeloma to 90% for patients with testicular cancer. Mortality rates moved closer to rates observed in the age- and sex-matched Australian general population over time but remained significantly increased 11 or more years from HSCT (standardized mortality ratio, 5.9). Although the proportion of deaths from nonrelapse causes increased over time, relapse remained the most frequent cause of death for all diagnoses, 10 or more years after autologous HSCT. Our findings show that prevention of disease recurrence remains 1 of the greatest challenges for autologous HSCT recipients, while the increasing rates of nonrelapse deaths due to the emergence of second cancers, circulatory diseases, and respiratory diseases highlight the long-term health issues faced by adult survivors of autologous HSCT.

Ex Vivo Expansion of Haematopoietic Stem Cells to Improve Engraftment in Stem Cell Transplantation

The efficient use of haematopoietic stem cells (HSC) for transplantation is often limited by the relatively low numbers of HSC collected. The ex vivo expansion of HSC for clinical use is a potentially valuable and safe approach to increase HSC numbers thereby increasing engraftment and reducing the risk of morbidity from infection. Here we describe a protocol for the robust ex vivo expansion of human CD34(+) HSC isolated from umbilical cord blood. The protocol described can efficiently generate large numbers of HSC. We also describe a flow cytometry-based method using high resolution division tracking to characterise the kinetics of HSC growth and differentiation. Utilising the guidelines discussed, it is possible for investigators to use this protocol as presented or to modify it for their specific needs.

A Pilot Study of a Computerized Decision Support System to Detect Invasive Fungal Infection in Pediatric Hematology/Oncology Patients

OBJECTIVE Computerized decision support systems (CDSSs) can provide indication-specific antimicrobial recommendations and approvals as part of hospital antimicrobial stewardship (AMS) programs. The aim of this study was to assess the performance of a CDSS for surveillance of invasive fungal infections (IFIs) in an inpatient hematology/oncology cohort. METHODS Between November 1, 2012, and October 31, 2013, pediatric hematology/oncology inpatients diagnosed with an IFI were identified through an audit of the CDSS and confirmed by medical record review. The results were compared to hospital diagnostic-related group (DRG) coding for IFI throughout the same period. RESULTS A total of 83 patients were prescribed systemic antifungals according to the CDSS for the 12-month period. The CDSS correctly identified 19 patients with IFI on medical record review, compared with 10 patients identified by DRG coding, of whom 9 were confirmed to have IFI on medical record review. CONCLUSIONS CDSS was superior to diagnostic coding in detecting IFI in an inpatient pediatric hematology/oncology cohort. The functionality of CDSS lends itself to inpatient infectious diseases surveillance but depends on prescriber adherence.

Ethical Issues Surrounding Umbilical Cord Blood Donation and Banking

Hematopoietic stem cell transplantation (HSCT) is curative therapy for many malignant and nonmalignant conditions including leukemia, bone marrow failure syndromes, immunodeficiencies, and inborn errors of metabolisms. Stem cells for HSCTs are typically sourced from compatible bone marrow or peripheral blood donors. However, over the last 2 decades umbilical cord blood (UCB), once considered a biological waste product, has become a routinely used source of hematopoietic stem cells. With this, there has been establishment of UCB banks, both not-for-profit “public” banks and private commercial banks, resulting in a large and growing inventory of this type of stem cell. This has raised a number of important scientific, ethical, legal, and political issues. These include ethical concerns regarding ownership of the blood, the processes for obtaining consent for collection and storage of UCB, issues relating to confidentiality and privacy, questions raised regarding commercial non-altruistic banking, and social justice issues relating to equity of access and equity of care.

Donor body mass index does not predict graft versus host disease following hematopoietic cell transplantation

Correspondence: Donor body mass index does not predict graft versus host disease following hematopoietic cell transplantation

Comparison of pediatric allogeneic transplant outcomes using myeloablative busulfan with cyclophosphamide or fludarabine

Busulfan combined with cyclophosphamide (BuCy) has long been considered a standard myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation (HCT), including both nonmalignant conditions and myeloid diseases. Substituting fludarabine for cyclophosphamide (BuFlu) to reduce toxicity without an increase in relapse has been increasingly performed in children, but without comparison with BuCy. We retrospectively analyzed 1781 children transplanted from 2008 to 2014 to compare the effectiveness of BuCy with BuFlu. Nonmalignant and malignant disease populations were analyzed separately. Overall mortality was comparable for children with nonmalignant conditions who received BuFlu or BuCy (relative risk [RR], 1.14, P = .52). Lower incidences of sinusoidal obstruction syndrome (P = .04), hemorrhagic cystitis (P = .04), and chronic graft-versus-host disease (P = .02) were observed after BuFlu, but the influence of the conditioning regimen could not be assessed by multivariate analysis because of the low frequency of these complications. Children transplanted for malignancies were more likely to receive BuFlu if they had higher hematopoietic cell transplantation-comorbidity index scores (P < .001) or their donor was unrelated and HLA-mismatched (P = .004). Nevertheless, there were no differences in transplant toxicities and comparable transplant-related mortality (RR, 1.2; P = .46), relapse (RR, 1.2; P = .15), and treatment failure (RR, 1.2; P = .12). BuFlu was associated with higher overall mortality (RR, 1.4; P = .008) related to inferior postrelapse survival (P = .001). Our findings demonstrated that outcomes after BuFlu are similar to those for BuCy for children, but for unclear reasons, those receiving BuFlu for malignancy may be at risk for shorter postrelapse survival.

Abstract 3760: Preclinical optimization of a low cost PiggyBac transposase (PB) generated CD19-specific chimeric antigen receptor T cell (CART19) product for a first in man trial using local hospital cell manufacture

BACKGROUND: CAR19 T cells show remarkable efficacy against relapsed/refractory B cell malignancies. PiggyBac offers a less complex and more cost effective means for generating CAR19 T cells compared to viral vectors typically used, so we aimed to use PiggyBac to generate a product suitable for translation to the clinic. METHODS: CAR19 T cells utilizing the CAR1928z construct have been found to perform well in vitro but had poor in vivo efficacy and persistence, most likely due to deleterious FcγR interactions via the IgG1 Fc-containing CAR spacer domain. We designed two new CARs and replaced the IgG1 Fc component of the spacer with a (G4S)3 linker. We used either CD28 or 4.1BB co-stimulatory domains (CAR19h28z and CAR19h41BBz, respectively), and generated CAR19 T cells using electroporation of PiggyBac transposon and transposase plasmids. Cells were expanded over 22 days through CD19 stimulation with IL-15 support. The two new CARs were compared to CAR1928z in vitro and their in vivo activity was assessed over 12 weeks in NSG mice xenografted with B-ALL. RESULTS: CAR19 T cell products generated using PiggyBac showed vigorous expansion (minimum 120-fold) and robust CAR expression (>80% T cells in final product). T cells generated using CAR19h28z displayed CD4 predominance (mean 85%) while CAR19h41BBz showed greater CD8 predominance (mean 62%). Naive and central memory T cells constituted 30 to 45% of CAR19 T cells in all products. IFN-γ production was specific to CD19+ targets and was demonstrated in both CD4+ and CD8+ CAR19 T cells. CD19 specific dose-dependent cytotoxicity was seen with all products, although to a significantly lower degree with CAR19h28z. In vivo, a single dose of either CAR19h28z or CAR19h41BBz T cells 1 week after B-ALL injection significantly delayed leukemia progression compared to untreated mice (median OS: 42 days for untreated vs >82 days [median not reached] for each CAR19 T cell product, P CONCLUSIONS: CAR19 T cells generated with PiggyBac, utilizing optimized CAR constructs without IgG1 Fc-containing spacers and with either CD28 or 4.1BB co-stimulatory domains, had potent activity against B-ALL in preclinical studies. We selected CAR19h41BBz to proceed to a first in man clinical trial of PiggyBac generated CAR19 T cells. The low cost and simplicity of our manufacturing process utilizing electroporation with PiggyBac elements and patient-derived materials means that decentralized, local hospital production is feasible. We predict that CAR T cell production with PiggyBac will greatly improve accessibility to CAR19 T cell therapy. Citation Format: David Bishop, Ning Xu, Sylvie Shen, Tracey O’Brien, David Gottlieb, Alla Dolnikov, Kenneth Micklethwaite. Preclinical optimization of a low cost PiggyBac transposase (PB) generated CD19-specific chimeric antigen receptor T cell (CART19) product for a first in man trial using local hospital cell manufacture [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3760. doi:10.1158/1538-7445.AM2017-3760