ALBERT

Description: Sperm parameters are known to be impaired in men with sickle cell disease (SCD). Although treatment with hydroxyurea (HU) impacts sperm quality, sperm preservation is impossible before puberty. The present study's primary objective was to analyze and compare sperm parameters in male SCD patients exposed (or not) to HU before puberty. Twenty-six sperm samples from 15 patients (median (range) age: 17 (16-23)) treated with HU during childhood were compared with 46 samples from 23 HU-naïve patients (median (range) age: 20 (16-24)). The median (range) age at HU initiation was 6 years (1-14), the median duration of HU treatment was 4 years (0.5-10) and the mean ± standard deviation dose of HU was 22.4 ± 3.7 mg/kg/day. Although we observed substantial quantitative and qualitative semen abnormalities in all patients, there were no significant differences in semen volume, sperm concentration, total sperm count, and spermatozoa motility, morphology and vitality between the HU-exposed and HU-naïve groups. At the time of the semen analysis, respectively 100% and 52% of the patients in the HU-exposed and HU-naïve groups were on transfusion therapy. Hydroxyurea's specific effect on spermatogenesis in very young infants and the putative value of transfusion for reversing HU's toxicity warrant further investigation.

Description: In gene therapy with human hematopoietic stem and progenitor cells (HSPCs), each gene-corrected cell and its progeny are marked in a unique way by the integrating vector. This feature enables lineages to be tracked by sampling blood cells and using DNA sequencing to identify the vector integration sites. Here, we studied 5 cell lineages (granulocytes, monocytes, T cells, B cells, and natural killer cells) in patients having undergone HSPC gene therapy for Wiskott-Aldrich syndrome or β hemoglobinopathies. We found that the estimated minimum number of active, repopulating HSPCs (which ranged from 2000 to 50 000) was correlated with the number of HSPCs per kilogram infused. We sought to quantify the lineage output and dynamics of gene-modified clones; this is usually challenging because of sparse sampling of the various cell types during the analytical procedure, contamination during cell isolation, and different levels of vector marking in the various lineages. We therefore measured the residual contamination and corrected our statistical models accordingly to provide a rigorous analysis of the HSPC lineage output. A cluster analysis of the HSPC lineage output highlighted the existence of several stable, distinct differentiation programs, including myeloid-dominant, lymphoid-dominant, and balanced cell subsets. Our study evidenced the heterogeneous nature of the cell lineage output from HSPCs and provided methods for analyzing these complex data.

Description: Background: In patients with hemoglobinopathies, hematopoietic stem cell (HSC) gene therapy has the potential to induce production of functional β-globin in the red blood cell lineage with the aim of reducing or eliminating the symptoms of disease. Previous results from 1 subject with severe sickle cell disease (SCD; 6 months follow-up) and 2 subjects with β0/βE-thalassemia major (up to 15 months follow-up) treated in clinical study HGB-205 suggested that transplantation with autologous CD34+ cells transduced with the LentiGlobin BB305 lentiviral vector containing an engineered βA-T87Q-globin gene (LentiGlobin BB305 Drug Product) resulted in near-normal levels of total hemoglobin (Hb) and rapid clinical improvement. Here we provide data on a new subject enrolled and additional follow-up data on the 3 subjects previously presented in Study HGB-205. Subjects and Methods: Subjects with severe SCD underwent HSC collection via bone marrow harvest, while subjects with β-thalassemia major underwent HSC collection via peripheral blood apheresis following mobilization. CD34+ cells were selected and transduced with LentiGlobin BB305 lentiviral vector to produce the drug product. Subjects underwent myeloablation with intravenous busulfan, followed by infusion of drug product. Subjects were monitored for hematological engraftment, vector copy number, βA-T87Q-globin expression, adverse events and transfusion requirements. Integration site analysis (ISA) and replication-competent lentivirus (RCL) assays were performed. Prophylactic RBC transfusions were continued in subjects with SCD who were on chronic transfusion pre-transplant to maintain HbS

Description: Non-HLA identical hematopoietic stem cell transplantation (HSCT) provides a corrective therapy for most life-threatening primary immunodeficiencies (PID) and some malignant hemopathies. Despite advances made, severe complications following the treatment such as the prolonged persistence of T cell immunodeficiency still limit the use of this partially incompatible HSCT. After HSCT, the reconstitution of a functional T cell compartment relies on the availability of T cell precursors to rapidly seed the thymus and differentiate into mature T cells. We have previously demonstrated that an in vitro culture system based on the use of a modified Delta-like-4 (DLL4) Notch ligand and T cell cytokines allows for the effective generation of human T cell precursors from cord blood within 7 days. Moreover, once injected into NOD/SCID/gcko mice, T cell precursors generated in this system were able to colonize the thymus and generate a diversified and functional T-cell compartment. Here, we aimed at testing the capacity of adult HSPCs in this reconstitution system. We found that, like their CB- derived counterparts, T cell precursors generated from adult HPSCs phenotypically resembled thymic CD34+CD7+ cells with high in vitro T-cell differentiation potential. Interestingly, the peak of T cell progenitors for adult HSPCs occurred around day 3, compared to day 7 in CB. At this timepoint, T cell precursors derived from adult HSPC already expressed all critical genes for T cell lineage development, as well as the major chemokine receptors implicated in thymus homing. The introduction of retronectin further improved differentiation and proliferation of T cell progenitors from both HPSC sources in our in vitro system. Comparative molecular analysis of adult- and CB- derived progenitors suggested, that differential requirements for Notch receptor/ligand interactions may explain the differences in kinetics observed during the culture of the two types of HSPC. It remains to be further evaluated, whether targeted modifications of the Notch signaling pathway can improve the outcome of this in vitro T cell differentiation system for adult HPSCs. Overall our results suggest that adult HSPCs, like their CB- derived counterparts, provide an effective source of in vitro cultured T cell progenitors harboring all the necessary requirements for the in vivo -reconstitution of a functional T cell compartment. This is particularly important in the context of future clinical applications in HSCT where adult HSPCs are more available and more frequently used than CB HSPCs. Based on our results, we propose that upon injection into a patient, DLL4- cultured T cell precursors from both HSPC sources could significantly accelerate the reconstitution of the adaptive immune system after a partially HLA-incompatible HSCT. Currently, we are translating these results into a phase I clinical trial including adult and pediatric patients transplanted for malignant hemopathies or PIDs requiring an allogeneic HSCT from a HLA-partially mismatched donors. Disclosures No relevant conflicts of interest to declare.

Description: Gene therapy represents an alternative and promising strategy that could provide a path to a curative therapy for HIV-1 infection. One approach involves the introduction of protective gene into a cell, thereby conferring protection against HIV. We plan to conduct an open label phase I/II gene therapy trial for HIV-1 infected patients presenting with lymphoma. The patients will received autologous hematopoietic stem cells transplantation with gene modified CD34+ cells and CD4+ T-cells. CD34+ and CD4+ will be ex vivo transduced by the LVsh5/C46 lentiviral vector (Cal-1, Calimmune, Inc. Tucson, USA). LVsh5/C46 is a SIN lentiviral vector that inhibits two crucial steps of CD4+ T cell infection by the HIV virus: (i) attachment of the virus to its target by downregulation of CCR5 via a short hairpin RNA, (ii) fusion of the virus to the target cell through expression of the C46 inhibitor. We developed a transduction process for CD4+ T-cells using the TransAct™ reagent (Miltenyi Biotec, Bergisch Gladbach , Germany) for CD4+ T-cells activation. Compared to previously published T-cells transduction protocols, the use of Miltenyi TransAct™ permits an equivalent efficacy of transduction - evaluated by measurement of vector copy number through quantitative PCR - without major phenotypic modification. Indeed, CD4+ T-cells ex vivo transduced after activation with the TransAct™ reagent display very few changes in their surface marker with conservation of naive (CCR7+CD62L+CD45RA+), central memory (CCR7+CD62L+CD45RA-) and effector memory (CCR7-CD62L-CD45RA-) subsets in superimposable proportions as initially. Moreover, expression of CD25 remains below 15-25% of cells suggesting a more "gentle " activation of the transduced CD4+ T-cells. Our transduction process had no significant impact in TCRβ repertoire diversity as evaluated by high-throughput sequencing and analyzis of diversity through the Gini-Simpson index or the Shannon index. Finally, transduced CD4 + T-cells retained the ability to to be primed towards the TH1, TH2 and TH17 pathways suggesting that the transduction protocol used did not alter the functional properties of the target cells. Disclosures No relevant conflicts of interest to declare.

Description: BACKGROUND Allogeneic hematopoietic stem cell (HSC) transplant is potentially curative for patients with β-thalassemia major or, as more broadly defined, transfusion dependent β-thalassemia (TDT). However, HSC transplant is generally restricted to younger patients with matched sibling donors. Gene therapy could provide a transformative treatment for a broader population of patients with TDT, including those who are older or lack an appropriate donor. HGB-204 is an international, multi-center Phase 1/2 clinical study investigating the safety and efficacy of LentiGlobin Drug Product (DP), a gene therapy product containing autologous HSCs transduced ex vivowith the BB305 lentiviral vector, in patients with TDT. We previously reported initial data in 13 treated patients with 0 to 19 months follow-up. Study enrollment is complete, and all 18 patients have undergone DP infusion. Here, we report new results on the study's full cohort of 18 patients, 14 of whom have ≥ 6 months of follow-up, including 1 who has completed the primary 24-month analysis period. METHODS Patients (12 to 35 years of age) with TDT were enrolled at participating sites in the U.S., Australia, and Thailand. HSC mobilization was accomplished with granulocyte colony stimulating factor (G-CSF) and plerixafor, and HSCs were harvested by apheresis. In a centralized manufacturing facility, CD34+-selected stem cells were transduced with the BB305 lentiviral vector, which encodes the human β-globin gene engineered to contain a single point mutation (AT87Q) and is regulated by the β-globin locus control region. Patients underwent myeloablation with intravenous busulfan, followed by infusion of transduced CD34+ cells (LentiGlobin DP). Patients were monitored for hematologic engraftment, vector copy number (VCN), hemoglobin AT87Q (HbAT87Q) expression, and transfusion requirements. Safety assessments including adverse clinical events (AEs), integration site analysis (ISA) and surveillance for replication competent lentivirus (RCL) were evaluated post-infusion. RESULTS Eighteen patients with TDT (β0/β0 [n=8], β0/βE [n=6], β0/β+ [n=1], β0/βx [n=1] and β+/β+ [n=2] genotypes) have received LentiGlobin DP. The median age of the 13 female and 5 male patients treated was 20 years (range: 12-35 years). The median DP VCN was 0.7 (range: 0.3-1.5 copies/diploid genome) and the median cell dose was 8.1 x 106 CD34+ cells/kg (range: 5.2-18.1 x 106 cells/kg). Patients engrafted with a median time of 18.5 days (range: 14-30 days) to neutrophil recovery. The toxicity profile observed was typical of myeloablative conditioning with single agent busulfan. There have been no ≥ Grade 3 DP-related AEs and no evidence of clonal dominance or RCL during a median follow-up of 14.4 months post-infusion (range: 3.7-27.0 months; cut-off date: 27 June 2016). To date, patients with at least 6 months of follow-up achieved a median HbAT87Q level of 4.7 g/dL at 6 months (range: 1.8-8.9 g/dL; n=14), with a median VCN in peripheral blood of 0.4 (range: 0.2−1.0; n=13). Of these, all patients with non-β0/β0 genotypes and ≥12 months of follow-up (n=5) have remained free of transfusions (median 19.4 months without transfusion; range: 15.3 to 24.0 months) with a median total Hb of 11.6g/dL (range: 9.0-11.9 g/dL) at the most recent follow-up visit. While patients with β0/β0genotypes and ≥12 months of follow-up (n=5) have continued to require transfusions, annual median transfusion volumes have decreased 60% (from median 171.9 ml/kg/year at baseline [range: 168.1-223.2ml/kg/year] to 67.8 ml/kg/year post-treatment [range: 14.8-123.7 ml/kg/year]). CONCLUSIONS In the largest TDT gene therapy trial to date, all patients have demonstrated therapeutic Hb expression without ≥ Grade 3 DP-related AEs. The levels of HbAT87Q in patients with at least 6 months of follow-up have exceeded the study primary endpoint (≥ 2g/dL) in 13/14 (93%) patients and are sustained in the 10 patients with ≥12 months of follow up. Compared to their baseline, all patients with β0/β0 genotypes have considerably reduced transfusion requirements. Notably, following a single infusion of LentiGlobin DP, patients with genotypes other than β0/β0 have discontinued transfusions and remain free of transfusions to date. These early results support the continued development of LentiGlobin DP as a treatment for TDT. Disclosures Thompson: Amgen: Research Funding; bluebird bio: Consultancy, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Mast: Research Funding; ApoPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Eli Lily: Research Funding; Baxalta (now part of Shire): Research Funding. Kwiatkowski:Luitpold Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Apopharma: Research Funding; Ionis pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Sideris Pharmaceuticals: Consultancy; Shire Pharmaceuticals: Consultancy. Rasko:GSK: Honoraria; IMAGO BioSciences: Consultancy, Equity Ownership; Genea: Consultancy, Equity Ownership; Rarecyte: Consultancy, Equity Ownership; Australian government and philanthropic foundations: Research Funding; Cure The Future Foundation: Other: Voluntary non-executive Board Member; Royal College of Pathologists of Australasia Foundation: Other: Voluntary non-executive Board Member; Office of the Gene Technology Regulator (OGTR) Australian Government: Membership on an entity's Board of Directors or advisory committees. Schiller:Incyte Corporation: Research Funding. Ho:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. von Kalle:bluebird bio: Consultancy; GeneWerk: Equity Ownership. Leboulch:bluebird bio: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding. Petrusich:bluebird bio: Employment, Equity Ownership. Asmal:bluebird bio: Employment, Equity Ownership. Walters:Kiadis Pharma: Honoraria; Bayer HealthCare: Honoraria; Leerink Partners, LLC: Consultancy; ViaCord Processing Laboratory: Other: Medical Director ; AllCells, Inc./LeukoLab: Other: Medical Director ; bluebirdBio, Inc: Honoraria.

Description: Background. Wiskott Aldrich Syndrome (WAS) is a rare primary immunodeficiency associated with thrombocytopenia, eczema, severe infectious and autoimmune complications, and lymphomas. Mismatched allogeneic hematopoietic stem cell transplantation (HSCT) is an alternative for patient lacking an HLA-matched donor but is associated with an increased frequency of complications. Moreover low lymphoid and myeloid chimerism is related to a higher rate of autoimmunity and thrombocytopenia. Recent gene therapy (GT) trials showed that gene-corrected autologous CD34+ cells infusion could be an appropriate therapeutic approach for these patients. It has been recently shown that B cell homeostasis is altered in WAS. As the B cell reconstitution participates to the restoration of immunological competence, a comprehensive study of this compartment after GT and the comparison with mismatched allogeneic HSCT is crucial. Objective. To perform a longitudinal study of B cell reconstitution in WAS patients after lentiviral vector-mediated GT, compared to mismatched allogeneic HSCT. Methods. Five patients (age 0.8-15.5 years) underwent GT at our center since 2011(follow-up 1.5-4.2 years) after near-myeloablative and immunosuppressive conditioning regimen with (n=3) or without (n=2) anti-CD20 administration. Patient 2 (P2) died 7 months after GT from a pre-existing infectious complication. Eleven patients undergoing mismatched allogeneic HSCT (age 0.6-10.9 years) at the same center were studied (follow-up 5.1-14.7 years). Longitudinal B cell assessment included B cell count before and after treatment, and the following subsets: switched memory (SM, CD19+ CD27+ IgD-), marginal zone (MZ, CD19+ CD27+ IgD+), naives (CD19+ CD27- IgD+), transitional (CD19+ CD27- IgD+ CD24high CD38high), circulating plasma cells (CD19+ CD27+ IgD- CD27high CD38high) and CD21low B cells (CD19+ CD21low CD38-), a subset abnormally expanded in WAS. Quantification of the B cell replication history was assessed through k-deleting recombination excision circles (KRECs). Analyses were compared to age-matched controls. WAS protein (WASP) expression and vector copy number (VCN) were measured in sorted B cells. Results. All alive GT patients show stable engraftment of functionally corrected lymphoid cells, without adverse events. Transduced B cells number and WASP expression increased progressively after GT. Absolute B cell count attained normal values in all the patients, and correlates with WASP expression and VCN in B cells. IgM levels are below normal ranges in four patients. P3 and P4 attained a B-cell phenotype within normal ranges; P3 discontinued intravenous immunoglobulin (IvIg) replacement. No expansion of CD21low B cells was observed. P1 and P5 (follow-up 18 months) present a variable defect in SM, naives and/or MZ B cells. P1 recently developed autoimmune manifestations; no significant changes were observed concomitantly. A defect in B cell lymphopoiesis was observed before GT as measured by KRECs analysis, normalizing after GT (P1, P3 and P4). Several complications were recorded in patients undergoing mismatched allogeneic HSCT, including dysimmunity, arthritis, developmental deficit and infections. Total B cell count normalized in eight patients, IgM levels were low in three. Among patients with available information, four still remain under IvIg replacement. Four patients developed a mixed lymphoid and myeloid chimerism, variably associated with low B cell count, low IgM and IvIg replacement. A complete B cell assessment for these patients is ongoing. Conclusions. B cell transgene expression is obtained after lentiviral vector-mediated GT in WAS patients and is associated with improved B cell lymphopoiesis. A correct B cell phenotype is observed in two patients who did not receive rituximab prior GT. The question whether this is related to the treatment will need a longer follow-up to be answered. Patients undergoing mismatched allogeneic HSCT present a higher frequency of complications. Although a higher proportion of these patients discontinued IvIg replacement, B cell reconstitution is not optimal. Analysis of patients in particular with mixed chimerism will provide important information in the setting of GT. The analysis of B cell reconstitution after GT and mismatched allogeneic HSCT deserves particular attention in the assessment of immunological reconstitution. Disclosures No relevant conflicts of interest to declare.

Description: Background: Hematopoietic stem cell (HSC) gene therapy has the potential to induce globin production and mitigate the need for blood transfusions in β-thalassemia major. Promising early results for 2 subjects with β0/βE -thalassemia major in the ongoing HGB-205 study suggested that transplantation with autologous CD34+ cells transduced with a replication-defective, self-inactivating LentiGlobin BB305 lentiviral vector containing an engineered β-globin gene (βA-T87Q) can be safe and yield robust production of βA-T87Qglobin resulting in rapid transfusion independence. The Northstar study (HGB-204), which uses the same lentivirus vector and analogous study design as study HGB-205, is multi-center and multi-national, and centralizes drug product manufacturing. Herein, we provide the initial data on subjects enrolled and treated in this study. Subjects and Methods: Transfusion-dependent subjects with β-thalassemia major undergo HSC collection via mobilized peripheral blood apheresis and CD34+ cells are selected. Estimation of the mean ex-vivo vector copy number (VCN) is obtained by quantitative PCR performed on pooled colony-forming progenitors. Subjects undergo myeloablation with intravenous busulfan, followed by infusion of transduced CD34+ cells. Subjects are monitored for hematologic engraftment, βA-T87Q -globin expression (by high performance liquid chromatography) and transfusion requirements. Integration site analysis (ISA, by linear amplification-mediated PCR and high-throughput sequencing on nucleated cells) and replication-competent lentivirus (RCL) assays are performed for safety monitoring. Results: As of 31 July 2014, 3 subjects have undergone HSC collection and ex-vivo LentiGlobin BB305 gene transfer. One subject (Subject 1102) has undergone myeloablation and drug product infusion. Outcomes data are shown in Table 1. The initial safety profile is consistent with myeloablation, without serious adverse events or gene therapy-related adverse events. This subject has increasing production of βA-T87Q-globin: the proportion of βA-T87Qglobin was 1.5%, 10.9% and 19.5% of total Hb at 1, 2 and 3 months post-infusion, respectively. This subject received pRBCs on Day +14 following drug product infusion and required no further transfusions until a single unit of pRBC was transfused on Day +96 for a Hb of 8.6 g/dL and fatigue. Two additional subjects have undergone drug product manufacture and are awaiting transplantation. Safety data related to ISA and RCL assays are pending. Abstract 549. Table 1 Preliminary results of dosing parameters and transplantation outcomes Subject Age (years) and Gender Genotype BB305 Drug Product Day of Neutrophil Engraftment Drug Product- related Adverse Events βA-T87Q-Hb at last follow-up visit /Total Hb (g/dL) VCN CD34+ cell dose (x106 per kg) 1102 18 F β0/βE 1.0/1.1a 6.5 Day +17 None 1.77/8.6 1104 21 F β0/βE 0.7/0.7a 5.4 P P P 1106 20 F β0/β0 1.5 12.3 P P P As of 31 July 2014; P, pending a If more than one drug product were manufactured, the VCN of each drug product lot is presented. Conclusion: The first subject treated on the Northstar study has safely undergone drug product infusion with autologous HSCs transduced with LentiGlobin BB305 lentiviral vector and is producing steadily increasing amounts of βA-T87Q-globin. Additional follow-up of this subject plus data on additional subjects who undergo drug product infusion will be presented at the meeting. Ex-vivo gene transfer of βA-T87Q-globin to autologous HSCs is a promising approach for the treatment of patients with β-thalassemia major. Disclosures Thompson: ApoPharma: Consultancy; Novartis: Consultancy, Research Funding; Amgen: Research Funding; Glaxo Smith Kline: Research Funding; Mast: Research Funding; Eli Lilly: Research Funding. Kwiatkowski:Shire Pharmaceuticals and Sideris Pharmaceuticals: Consultancy. Schiller:Sunesis, Amgen, Pfizer, Bristol Myers Squibb: Research Funding. Leboulch:bluebird bio: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Petrusich:bluebird bio, Inc.: Employment, Equity Ownership. Soni:bluebird bio, Inc.: Employment. Walters:Via Cord and AllCells, Inc.: Medical Director Other.