Acute Myeloid Leukemia Case after Gene Therapy for Sickle Cell Disease.

Gene therapy with LentiGlobin for sickle cell disease (bb1111, lovotibeglogene autotemcel) consists of autologous transplantation of a patient's hematopoietic stem cells transduced with the BB305 lentiviral vector that encodes the ßA-T87Q-globin gene. Acute myeloid leukemia developed in a woman approximately 5.5 years after she had received LentiGlobin for sickle cell disease as part of the initial cohort (Group A) of the HGB-206 study. An analysis of peripheral-blood samples revealed that blast cells contained a BB305 lentiviral vector insertion site. The results of an investigation of causality indicated that the leukemia was unlikely to be related to vector insertion, given the location of the insertion site, the very low transgene expression in blast cells, and the lack of an effect on expression of surrounding genes. Several somatic mutations predisposing to acute myeloid leukemia were present after diagnosis, which suggests that patients with sickle cell disease are at increased risk for hematologic malignant conditions after transplantation, most likely because of a combination of risks associated with underlying sickle cell disease, transplantation procedure, and inadequate disease control after treatment. (Funded by Bluebird Bio.).

Immune Reconstitution and Infection Patterns after Early Alemtuzumab and Reduced Intensity Transplantation for Nonmalignant Disorders in Pediatric Patients.

Hematopoietic stem cell transplantation (HSCT) is a therapeutic option for many nonmalignant disorders (NMD) and is curative or prevents disease progression. Reduced-intensity conditioning (RIC) in HSCT for NMD may reduce regimen-related acute toxicities and late complications. Myeloablation is often replaced by immune suppression in RIC regimens to support donor engraftment. The pace of immune reconstitution after immune suppression by RIC regimens is influenced by agents used, donor source, and graft-versus-host disease prophylaxis/treatment. In a multicenter trial (NCT 00920972) of HSCT for NMD, a RIC regimen consisting of alemtuzumab, fludarabine, and melphalan was substituted for myeloablation. Alemtuzumab was administered early (days -21 to -19) to mitigate major lymphodepletion of the incoming graft and the risk of graft rejection. Immune reconstitution and infectious complications were prospectively monitored for 1-year post-HSCT. Seventy-one patients met inclusion criteria for this report and received marrow or peripheral blood stem cell transplants. Immune reconstitution and infections are reported for related donor (RD) and unrelated donor (URD) transplants at 3 time-points (100days, 6 months, and 1 year post-HSCT). Natural killer cell recovery was rapid, and numbers normalized in both cohorts by day +100. Mean CD3, CD4, and CD8 T-lymphocyte numbers normalized by 6 months after RD HSCT and by 1 year in the URD group. CD4 and CD8 T-lymphocyte counts were significantly higher in patients who received RD HSCT at 6 months and at 1 year, respectively, post-HSCT compared with patients who received URD HSCT. The pace of CD19 B-cell recovery was markedly different between RD and URD cohorts. Mean B-cell numbers were normal by day 100 after RD HSCT but took 1 year post-HSCT to normalize in the URD cohort. Despite these differences in immune reconstitution, the timing and nature of infections did not differ between the groups, presumably because of comparable T-lymphocyte recovery. Immune reconstitution occurred at a faster pace than in prior reports using RIC with T-cell depletion. The incidence of infections was similar for both cohorts and occurred most frequently in the first 100days post-HSCT. Viral and fungal infections occurred at a lower incidence in this cohort, with "early" alemtuzumab compared with regimens administering serotherapy in the peritransplantation period. Patients were susceptible to bacterial infections primarily in the first 100days irrespective of donor source and had no increase in mortality from the same. The overall mortality rate from infections was 1.4% at 1 year. Close monitoring and prophylaxis against bacterial infections in the first 100days post-HSCT is necessary but is followed by robust immune reconstitution, especially in the T-cell compartment.

The effect of bone marrow graft composition on pediatric bone marrow transplantation outcomes.

Hematopoietic stem cell graft cellular composition has been generally accepted to impact outcomes. Recent studies question this hypothesis. We conducted a single-center retrospective study of sixty-one pediatric BMT recipients for malignant (68%) and nonmalignant diseases (32%) examining effects of graft composition on engraftment, acute GVHD, chronic GVHD, and survival at day 100 and 1 year. Grafts contained a median of 3.63 x  08 TNC/kg (range: 0.031-10.31 x 108 TNC/kg) and 4.09 x 106 CD34+ /kg (range: 0.76-24.15 x 106 CD34+ /kg) with median neutrophil and platelet engraftment times of 17 and 29 days, respectively. A univariate analysis showed a trend for increasing TNC and increasing time to neutrophil engraftment HR: 0.875; CI: 0.075-1.001). Increasing CD34+ counts shortened time to platelet engraftment (HR: 1.085; CI: 1.015-1.161). No significant relationship was found between TNC, CD34+ , or CD3+ and acute or chronic GVHD. TNC or CD34+ did not affect day 100, 1-year survival, or 2-year survival. Increasing CD3+ counts demonstrated a negative trend on day 100 survival (HR: 1.108; CI: 1.001-1.036) but not 1-year survival or 2-year survival. These results add additional data questioning the effect of graft composition on outcomes in pediatric BMT patients with important ramifications for the management of donors.

A trial of unrelated donor marrow transplantation for children with severe sickle cell disease.

Children with sickle cell disease experience organ damage, impaired quality of life, and premature mortality. Allogeneic bone marrow transplant from an HLA-matched sibling can halt disease progression but is limited by donor availability. A Blood and Marrow Transplant Clinical Trials Network (BMT CTN) phase 2 trial conducted from 2008 to 2014 enrolled 30 children aged 4 to 19 years; 29 were eligible for evaluation. The primary objective was 1-year event-free survival (EFS) after HLA allele-matched (at HLA-A, -B, -C, and -DRB1 loci) unrelated donor transplant. The conditioning regimen included alemtuzumab, fludarabine, and melphalan. Graft-versus-host disease (GVHD) prophylaxis included calcineurin inhibitor, short-course methotrexate, and methylprednisolone. Transplant indications included stroke (n = 12), transcranial Doppler velocity >200 cm/s (n = 2), ≥3 vaso-occlusive pain crises per year (n = 12), or ≥2 acute chest syndrome episodes (n = 4) in the 2 years preceding enrollment. Median follow-up was 26 months (range, 12-62 months); graft rejection was 10%. The 1- and 2-year EFS rates were 76% and 69%, respectively. The corresponding rates for overall survival were 86% and 79%. The day 100 incidence rate of grade II-IV acute GVHD was 28%, and the 1-year incidence rate of chronic GVHD was 62%; 38% classified as extensive. There were 7 GVHD-related deaths. A 34% incidence of posterior reversible encephalopathy syndrome was noted in the first 6 months. Although the 1-year EFS met the prespecified target of ≥75%, this regimen cannot be considered sufficiently safe for widespread adoption without modifications to achieve more effective GVHD prophylaxis. The BMT CTN #0601 trial was registered at www.clinicaltrials.gov as #NCT00745420.

Alemtuzumab based reduced intensity transplantation for pediatric severe aplastic anemia.

BACKGROUND: Hematopoietic cell transplantation (HCT) is curative in patients with severe aplastic anemia (SAA). HCT is considered at presentation when a HLA-matched related donor (MRD) is available and has a high success rate. Unrelated donor (URD) transplants are typically undertaken if immunosuppressive therapy fails. Increased toxicity and graft rejection are often encountered in this setting. PROCEDURE: We report a prospective multi-center trial of HCT in 17 children with SAA following novel reduced intensity conditioning with alemtuzumab, fludarabine and melphalan, and the best available donor. Nine were URD transplants matched at 7-8/8 loci, and performed following failure of immune suppression. Median follow up was 61 months (range 6-128). RESULTS: All patients engrafted. Estimated 5 year event-free and overall-survival was 88% (95%CI 65.7-96.7). Five year overall survival for MRD and URD transplants was 100% and 78% (95%CI 45-93.6) respectively. Median times to neutrophil and platelet engraftment was 14 (range 10-27) and 23.5 (range 11-65) days respectively. Treatment related mortality was 12%. The incidence of grade II-IV and III-IV acute graft-versus-host disease was 29% and 18% respectively. At two years, all but one patient discontinued immunosuppression successfully. Laboratory measures of immune reconstitution normalized at one year and infection rates were low in the latter part of the first year. CONCLUSIONS: HCT using this RIC approach was well tolerated and successful in achieving donor engraftment and early immune reconstitution with good quality of life free of immune suppression. Children with SAA can be successfully transplanted using alemtuzumab based conditioning.

Successful treatment of EBV-associated posttransplantation lymphoma after cord blood transplantation using third-party EBV-specific cytotoxic T lymphocytes.

Cellular therapy of Epstein-Barr virus (EBV)(+) posttransplantation lymphoproliferative diseases (PTLD) in cord blood transplant (CBT) recipients is limited by lack of donor access and the donor's naive neonatal immune system. We therefore used partially human leukocyte antigen-matched third-party in vitro expanded EBV-specific cytotoxic T lymphocytes (CTLs) to treat 2 CBT recipients with life-threatening, donor-derived monoclonal EBV(+) diffuse large B-cell lymphomas with extranodal involvement developing in the context of graft-versus-host disease. Both patients had failed immunosuppression taper and Rituximab. After 5 and 9 infusions of 10(6) EBV-CTL/kg, respectively, each patient achieved a sustained complete remission without toxicity or graft-versus-host disease. Each is alive without recurrence at 20 and 15 months, respectively, post-EBV-PTLD diagnosis. This approach demonstrates the efficacy of using "off-the-shelf," virus-specific third-party CTLs restricted by human leukocyte antigens expressed by the tumor to treat otherwise lethal EBV-PTLD. Such therapy may also be applicable to the treatment of other infections and residual or recurrent malignancy after CBT.

Influence of human leucocyte antigen disparity and graft lymphocytes on allogeneic engraftment and survival after umbilical cord blood transplant in adults.

The dose of graft-nucleated cells and CD34(+) haematopoietic progenitor cells are predictors of allogeneic engraftment and survival in umbilical cord blood (UCB) recipients. In this single institution prospective phase II trial, flow cytometric analyses of CD34(+) progenitor and lymphocyte populations in unmodified single unit human leucocyte antigen (HLA)-disparate UCB grafts infused into 31 consecutive adults (median age 41 years, range 20-64) receiving myeloablative conditioning were compared with clinical outcomes. Median infused UCB graft-nucleated cells and CD34(+) dose was 2.2 x 10(7)/kg and 1.2 x 10(5)/kg respectively. Day to absolute neutrophil count >/=0.5 x 10(9)/l with full donor chimerism averaged 27 d (range 12-41). Univariate analyses demonstrated that UCB graft-infused cell doses of CD34(+) (P = 0.015), CD3(+) (P = 0.024) and CD34(+)HLADR(+)CD38(+) progenitors (P = 0.043) correlated with neutrophil engraftment. This same analysis did not demonstrate a correlation between CD34(+) (P = 0.11), CD3(+) (P = 0.28) or CD34(+)HLADR(+)CD38(+) (P = 0.108) cell dose and event-free survival (EFS). High-resolution matching for HLA-class II (DRB1) resulted in improved EFS (P = 0.02) and decreased risk for acute graft-versus-host disease (GVHD) (P = 0.004). Early mortality (prior to post-transplant day +28) occurred in three patients, while 26 patients achieved myeloid engraftment. These results suggest that UCB graft matching at DRB1 is an important risk factor for acute GVHD and survival, while higher UCB graft cell doses of CD34(+), committed CD34(+) progenitors and CD3(+) T cells favourably influence UCB allogeneic engraftment.

Recipient-specific tolerance after HLA-mismatched umbilical cord blood stem cell transplantation.

BACKGROUND: Lower incidence and severity of acute graft versus host disease (GVHD) has been observed in leukemia patients receiving HLA-mismatched umbilical cord (UCB) transplants. However, despite the increased use of UCB in stem cell transplantation, the mechanisms underlying these favorable outcomes are not well delineated. METHODS: We analyzed antigen specific lymphocyte responses after transplant to determine whether the decreased allogeneic responsiveness of UCB lymphocytes is attributable to pan-unresponsiveness, lymphocyte repressive or recipient-specific tolerance. RESULTS: Circulating lymphocytes collected early (3 months) after UCB transplant demonstrate a less naïve phenotype compared with that in the infused graft. Additionally, after transplant, circulating peripheral blood UCB-derived lymphocytes produced normal levels of interferon-gamma and proliferated normally when stimulated with mitogen or third party alloantigen. In contrast, when stimulated with recipient antigen, circulating lymphocytes emerging posttransplant did not proliferate nor produce interferon-gamma. Moreover, analysis of interleukin-4 production revealed a Th2 response to recipient antigens. These data indicate early induction of immune tolerance of naïve UCB graft lymphocytes with skewing of transplant recipient-specific immune response towards Th2 cytokine profile. CONCLUSIONS: UCB graft lymphocyte immune naivety and observed early tolerance induction may contribute to the observed favorable GVHD incidence, despite infusion of HLA mismatch grafts in the unrelated allogeneic setting.

Augmentation of umbilical cord blood (UCB) transplantation with ex vivo-expanded UCB cells: results of a phase 1 trial using the AastromReplicell System.

Allogeneic stem cell transplantation with umbilical cord blood (UCB) cells is limited by the cell dose a single unit provides recipients. Ex vivo expansion is one strategy to increase the number of cells available for transplantation. Aastrom Biosciences developed an automated continuous perfusion culture device for expansion of hematopoietic stem cells (HSCs). Cells are expanded in media supplemented with fetal bovine serum, horse serum, PIXY321, flt-3 ligand, and erythropoietin. We performed a phase 1 trial augmenting conventional UCB transplants with ex vivo-expanded cells. The 28 patients were enrolled on the trial between October 8, 1997 and September 30, 1998. UCB cells were expanded in the device, then administered as a boost to the conventional graft on posttransplantation day 12. While expansion of total cells and colony-forming units (CFUs) occurred in all cases, the magnitude of expansion varied considerably. The median fold increase was 2.4 (range, 1.0-8.5) in nucleated cells, 82 (range, 4.6-266.4) in CFU granulocyte-macrophages, and 0.5 (range, 0.09-2.45) in CD34+ lineage negative (lin-) cells. CD3+ cells did not expand under these conditions. Clinical-scale ex vivo expansion of UCB is feasible, and the administration of ex vivo-expanded cells is well tolerated. Augmentation of UCB transplants with ex vivo-expanded cells did not alter the time to myeloid, erythroid, or platelet engraftment in 21 evaluable patients. Recipients of ex vivo-expanded cells continue to have durable engraftment with a median follow-up of 47 months (range, 41-51 months). A randomized phase 2 study will determine whether augmenting UCB transplants with ex vivo-expanded UCB cells is beneficial.

Hematopoietic recovery after unrelated umbilical cord-blood allogeneic transplantation in adults treated with in vivo stem cell factor (R-MetHuSCF) and filgrastim administration.

Transplantation with unrelated umbilical cord blood (UCB) is marked by delayed hematologic recovery. This report summarizes two adults with chronic myelogenous leukemia (CML), who received myeloablative conditioning followed by infusion of a non-expanded single UCB graft. These CML patients were enrolled in a clinical trial incorporating concomitant in vivo administration of stem cell factor (R-MetHuSCF) and filgrastim from day of UCB infusion until attained hematopoietic recovery. Each patient engrafted fully with donor UCB, with days to absolute neutrophil count (ANC) >500/microl being 13 and 29 days, respectively. Both patients remain in cytogenetic remission at 28 months follow-up. 'In vivo UCB expansion' with administration of concomitant R-MetHuSCF and filgrastim may facilitate prompt hematologic engraftment.