To determine the dose-limiting toxicity and maximum-tolerated dose of the proteasome inhibitor bortezomib administered intravenously weekly for 4 every 5 weeks; to determine the bortezomib ...pharmacokinetics and pharmacodynamics using plasma levels and an assay for 20S proteasome inhibition (PI) in whole blood; to correlate toxicity with bortezomib dose and degree of 20S PI; and to conduct a preliminary determination of the antitumor activity of bortezomib in patients with androgen independent prostate cancer (AIPCa).
Fifty-three patients (48 with AIPCa) received 128 cycles of bortezomib in doses ranging from 0.13 to 2.0 mg/m(2)/dose, utilizing a careful escalation scheme with a continuous reassessment method. Pharmacokinetic and pharmacodynamic studies were performed in 24 patients (at 1.45 to 2.0 mg/m(2)).
A dose-related 20S PI was seen, with dose-limiting toxicity at 2.0 mg/m(2) (diarrhea, hypotension) occurring at an average 1-hour post-dose of >/= 75% 20S PI. Other side effects were fatigue, hypertension, constipation, nausea, and vomiting. No relationship was seen between body-surface area and bortezomib clearance over the narrow dose range tested. There was evidence of biologic activity (decline in serum prostate-specific antigen and interleukin-6 levels) at >/= 50% 20S PI. Two patients with AIPCa had prostate-specific antigen response and two patients had partial response in lymph nodes.
The maximum-tolerated dose and recommended phase II dose of bortezomib in this schedule is 1.6 mg/m(2). Biologic activity (inhibition of nuclear factor-kappa B-related markers) and antitumor activity is seen in AIPCa at tolerated doses of bortezomib. This agent should be further explored with chemotherapy agents in advanced prostate cancer.
Gene therapy with CD34+ cells transduced with a lentivirus vector carrying a β-globin gene was performed in 22 patients. At a median of 26 months, all the patients were either transfusion-independent ...or had a major reduction in transfusion requirements.
Background
Sickle cell disease (SCD) is a recessive monogenic disease caused by a single point mutation in which glutamic acid replaces valine in Codon 6 of the human beta-globin gene (HBB) leading ...to the production of abnormal globin chains (HbS) that polymerize and cause erythrocytes to sickle. This results in hemolytic anemia, vaso-occlusion and organ damage, which leads to lifelong complications and early mortality. Allogeneic hematopoietic stem cell transplant (allo-HSCT) is the only known cure for SCD, however, its use is limited by the lack of well-matched donors, need for immunosuppression, risk of graft versus host disease and graft rejection.
GPH101 is an investigational, autologous, hematopoietic stem cell (HSC) drug product (DP) designed to correct the SCD mutation in the HBB gene ex vivo using a high fidelity Cas9 (CRISPR associated protein 9) paired with an AAV6 (adeno-associated virus type 6) delivery template, efficiently harnessing the natural homology directed repair (HDR) cellular pathway. This approach has the potential to restore normal adult hemoglobin (HbA) production while simultaneously reducing HbS levels. In preclinical studies, HBB gene correction in SCD donor HSCs resulted in ≥60% of gene-corrected alleles in vitro with minimal off-target effects. Gene corrected cells were successfully differentiated toward the erythroid lineage and produced ≥70% HbA in vitro. Long-term engraftment of gene-corrected HSCs was demonstrated in vivo, following transplant into immunodeficient mice, with multi-lineage allelic gene correction frequencies well above the predicted curative threshold of 20%, with potential of this approach to be equivalent or superior to allo-HSCT. In addition, HSC-based correction in an SCD mouse model led to stable adult hemoglobin production, increased erythrocyte lifespan and reduction in sickling morphology, demonstrating the therapeutic potential of this gene correction platform as a curative approach in SCD.
Study Design and Methods
CEDAR (NCT04819841) is a first-in-human, open-label, single-dose, multi-site Phase 1/2 clinical trial in participants with severe SCD designed to evaluate safety, efficacy and pharmacodynamics (PD) of GPH101. Approximately 15 adult (18-40 years) and adolescent (12-17 years) participants will be enrolled across 5 sites, with adolescent enrollment proceeding after a favorable assessment of adult safety data by a Safety Monitoring Committee.
Participants must have a diagnosis of severe SCD (βS/βS), defined as ≥ 4 severe vaso-occlusive crises (VOCs) in the 2 years prior and/or ≥ 2 episodes of acute chest syndrome (ACS), in 2 years prior with at least 1 episode in the past year. Participants on chronic transfusion therapy may be eligible if required VOC and ACS criteria are met in the 2 years prior to the initiation of transfusions. Key exclusion criteria include availability of a 10/10 human leukocyte antigen-matched sibling donor, or prior receipt of HSCT or gene therapy. After eligibility confirmation including screening for pre-treatment cytogenetic abnormalities, participants will undergo plerixafor mobilization and apheresis, followed by CD34+ cell enrichment and cryopreservation, undertaken locally at each trial site before shipment to a centralized manufacturer for GPH101 production.
After GPH101 release, participants will undergo eligibility reconfirmation prior to busulfan conditioning and DP infusion. Safety, efficacy and PD measurements will occur for 2 years post-infusion; a long-term follow up study will be offered to participants for an additional 13 years of monitoring.
The primary endpoint for this study is safety, measured by the kinetics of HSC engraftment, transplant related mortality, overall survival and frequency and severity of adverse events. Secondary endpoints will explore efficacy and PD, including levels of globin expression as compared to baseline, gene correction rates, clinical manifestations of SCD (including VOC and ACS), laboratory parameters, complications and organ function. In addition, cerebral hemodynamics and oxygen delivery will be assessed by magnetic resonance techniques. Key exploratory endpoints include evaluation of patient-reported outcomes, erythrocyte function, on-target and off-target editing rates, and change from baseline in select SCD characteristics.
Kanter: Fulcrum Therapeutics, Inc.: Consultancy; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Forma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees; Beam: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Graphite Bio: Consultancy; GuidePoint Global: Honoraria; Fulcrum Tx: Consultancy. Thompson: Agios Pharmaceuticals: Consultancy; Graphite Bio: Research Funding; Vertex: Research Funding; Beam Therapeutics: Consultancy; Celgene: Consultancy, Research Funding; Biomarin: Research Funding; Baxalta: Research Funding; CRISPR Therapeutics: Research Funding; Global Blood Therapeutics: Current equity holder in publicly-traded company; bluebird bio: Consultancy, Research Funding; Novartis: Research Funding. Porteus: Versant Ventures: Consultancy; CRISPR Therapeutics: Current equity holder in publicly-traded company; Allogene Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Ziopharm: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Graphite Bio: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Intondi: Graphite Bio: Current Employment, Current equity holder in publicly-traded company; Global Blood Therapeutics: Current equity holder in publicly-traded company, Ended employment in the past 24 months. Lahiri: Graphite Bio: Current Employment, Current equity holder in publicly-traded company. Dever: Graphite Bio: Current Employment, Current equity holder in publicly-traded company. Petrusich: bluebird bio: Current equity holder in publicly-traded company, Ended employment in the past 24 months; Graphite Bio: Current Employment, Current equity holder in publicly-traded company. Lehrer-Graiwer: Global Blood Therapeutics: Current equity holder in publicly-traded company, Ended employment in the past 24 months; Graphite Bio: Current Employment, Current equity holder in publicly-traded company.
Background
Patients with transfusion-dependent β-thalassemia (TDT) may experience transfusional iron overload and end-organ damage. While potentially curative, allogeneic hematopoietic stem cell ...(HSC) transplantation is limited by transplant-related risks and donor availability. Transplantation of autologous CD34+ cells encoding a βA-T87Q-globin gene (LentiGlobin gene therapy for β-thalassemia) may overcome some of these limitations. βA-T87Q-globin is incorporated into adult hemoglobin (Hb), forming gene therapy-derived HbAT87Q, which can be distinguished from other Hb species. The phase 1/2 Northstar study (HGB-204; NCT01745120) using the original manufacturing process evaluated the safety and efficacy of LentiGlobin in adolescents and adults with TDT (≥100 mL/kg/yr of red blood cells RBCs or ≥8 RBC transfusions/yr) and non-β0/β0 or β0/β0 genotypes.
Methods
HSCs were mobilized with G-CSF and plerixafor and collected via apheresis. CD34+ cells were transduced with BB305 lentiviral vector. After busulfan myeloablation, patients were infused with transduced cells. Primary efficacy endpoints were sustained production of ≥2 g/dL HbAT87Q between months 18 and 24 and transfusion independence (TI; weighted average Hb ≥9 g/dL without RBC transfusions for ≥12 months). Patients were monitored for 2 years and subsequently enrolled in the 13-year long-term follow-up study, LTF-303 (NCT02633943). Results are shown as median (min ‒ max) unless otherwise indicated.
Results
Eighteen patients were treated (age: 20 12 - 35 yrs) and followed for 40.7 (29.3 - 53.8) months as of 13 December 2018. In the 2 years prior to enrollment, patients had an annualized transfusion volume of 169.0 (124.0 - 273.0) mL/kg/yr and pre-transfusion weighted mean nadir Hb of 9.3 (7.0 - 10.1) g/dL.
Neutrophil and platelet engraftment occurred at 18.5 (14 - 30) and 39.5 (19 - 191) days, respectively. No patient had graft failure. Grade ≥3 non-hematologic adverse events (AEs) reported in ≥25% of patients after infusion were stomatitis, febrile neutropenia, and pharyngeal inflammation. No replication-competent lentivirus or death has been reported. The vector integration site profile in all 18 patients has remained polyclonal. The number of unique integration sites (UIS) identified was 1646 (190 - 2888), 1677 (151 - 6935), 2484 (984 - 5511), 1773 (1260 - 2693) at Months 12 (n=18), 24 (n=18), 36 (n=11), 48 (n=4), respectively. The highest mean (SD) frequency of any UIS in patients across all visits was 11.5% (5.8%). No oncogenesis has been reported.
In Northstar, 16/18 (89%) patients achieved the primary endpoint of ≥2 g/dL HbAT87Q between months 18 and 24. Eight of 10 (80%) patients with non-β0/β0 genotypes achieved and maintained TI; current duration of TI was 38 (21.2 - 45.3) months (Figure 1). The weighted average total Hb during TI was 10.3 (9.1 - 13.2) g/dL. Total Hb and HbAT87Q remained stable over time. Total Hb in patients with non-β0/β0 genotypes who achieved TI was 10.3, 10.4, 10.6, and 11.1 g/dL at Months 12 (n=8), 24 (n=8), 36 (n=7), 48 (n=3), respectively. Transfusion volumes were reduced by 73% and 43% in the 2 patients still receiving transfusions.
Three of 8 (38%) patients with β0/β0 genotypes achieved TI with a current duration of 16.4 (16.1 - 20.8) months. Weighted average total Hb during TI was 9.9 (9.5 - 10.1) g/dL and HbAT87Q was 8.0 - 8.9 g/dL at last visit. One additional patient was transfusion-free for 13.7 months; however, total Hb was <9 g/dL. The 4 other patients had a transfusion volume reduction of 53% (10% - 72%).
Patients who achieved TI resumed iron chelation 13 (2 - 15) months after infusion and all remain on iron chelation as of last follow-up. Serum ferritin and liver iron content (LIC) (Figure 2A, 2B) were reduced in patients who achieved TI by 55% (16 - 78%) and 56% (38 - 83%) from screening to Month 48 (n=4), respectively. Of these 4 patients who had a Month 48 visit, LIC values were 0.8 - 7.1 mg/g at Month 48 compared to 4.8 - 11.5 mg/g at screening. In patients who achieved TI, cardiac T2* ranged from 27.0 - 39.0 msec at screening and 31.4 - 57.6 msec at last visit.
Summary
With up to 4.5 years of follow-up after LentiGlobin gene therapy, generally stable HbAT87Q levels and durable TI were observed in 8/10 and 3/8 patients with TDT and non-β0/β0 and β0/β0 genotypes, respectively. Iron burden has improved over time in patients who achieved TI. The safety profile of LentiGlobin remains consistent with myeloablative conditioning.
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Kwiatkowski:Imara: Consultancy; Agios: Consultancy; bluebird bio, Inc.: Consultancy, Research Funding; Terumo: Research Funding; Apopharma: Research Funding; Novartis: Research Funding; Celgene: Consultancy. Thompson:bluebird bio, Inc.: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Baxalta: Research Funding. Rasko:GSK: Honoraria; bluebird bio: Honoraria; Imago: Consultancy; Novartis: Honoraria; Cynata: Honoraria; Spark: Honoraria; Takeda: Honoraria; NHMRC Mitochondrial Donation Expert Working Committee: Other: Advisory Committee; Gilead: Honoraria; Cure The Future Foundation: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; Genea: Equity Ownership; Rarecyte: Consultancy, Equity Ownership; Gene Technology Technical Advisory, Australian Government: Other: Advisory committee; Celgene: Honoraria; Advisory Committee on Biologics, Australian Government: Other: Advisory Committee; Australian Cancer Research Scientific Advisory Board: Membership on an entity's Board of Directors or advisory committees; FSHD Global Research Foundation: Membership on an entity's Board of Directors or advisory committees. Schiller:Amgen: Other, Research Funding; Agios: Research Funding, Speakers Bureau; Astellas: Research Funding; Biomed Valley Discoveries: Research Funding; Bristol Myer Squibb: Research Funding; Celgene: Research Funding, Speakers Bureau; Constellation Pharmaceutical: Research Funding; Daiichi Sankyo: Research Funding; Eli Lilly and Company: Research Funding; FujiFilm: Research Funding; Genzyme: Research Funding; Gilead: Research Funding; Incyte: Research Funding; J&J: Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Karyopharm: Research Funding; Novartis: Research Funding; Onconova: Research Funding; Pfizer Pharmaceuticals: Equity Ownership, Research Funding; Sangamo Therapeutics: Research Funding. Cavazzana:Smartimmune: Other: Founder of Smartimmune. Ho:Celgene: Other: investigator meeting travel costs; Janssen: Other: investigator meeting travel costs; Novartis: Other: investigator meeting travel costs; La Jolla: Other: investigator meeting travel costs. Schmidt:German Cancer Research Center, Heidelberg, Germany: Employment; GeneWerk GmbH, Heidelberg, Gemrany: Equity Ownership. Vichinsky:Agios: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; GBT: Consultancy, Research Funding; bluebird bio: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Deary:bluebird bio, Inc.: Employment, Equity Ownership. Chen:bluebird bio, Inc.: Consultancy. Petrusich:bluebird bio, Inc.: Employment, Equity Ownership. Walters:Editas Medicine: Consultancy; TruCode: Consultancy; AllCells, Inc: Consultancy.
Introduction
We investigated the impact of β-thalassemia genotypes and disease genetic modifiers including HBA and KLF1 genotype and sentinel single-nucleotide polymorphism (SNP) genotypes at 3 major ...HbF quantitative trait loci (QTL) on clinical outcomes of TDT patients treated with beti-cel gene therapy in two phase 3 studies, HGB-207 (NCT02906202) and HGB-212 (NCT03207009).
Methods
HBA deletions and triplications were determined by gap-polymerase chain reactions. HBG2 (including rs7482144, Xmn1 site) and HBG1 promoters, HBA2, HBA1, and KLF1 underwent individual nucleotide sequencing. Multiplex amplification refractory mutation system (ARMS) tests were used to identify HbF QTL SNPs (rs10128556 in HBBP1; rs766432, rs1427407, rs10189857 in BCL11A; rs9399137, rs66650371 in HMIP). Thalassemia severity score (TSS) was calculated as defined by Danjou et al, Haematologica, 2015, considering gender, HBB and HBA genotypes, and 4 SNPs in HbF QTL (HBG2, BCL11A, HMIP). Correlative analyses were performed to assess relationships between genotype, presence/absence of non-HBB mutations (HBA2, HBA1, KLF1), presence/absence of HbF QTL SNPs (HBG2, BCL11A, HMIP), and TSS with the achievement of transfusion independence (TI; weighted average hemoglobin Hb ≥9 g/dL without red blood cell RBC transfusions for ≥12 months). Correlation coefficients used percentage bend correlation. Statistical significance threshold was p ≤ 0.05.
Results
As of 3 March 2020, 38 patients were treated in HGB-207 and HGB-212 (β0/β0 genotype n=9; non-β0/β0 genotype n=29 β+/β+ n=8; β0/β+ n=15; βE/β0 n=6). All patients were heterozygous or homozygous for mutations or SNPs that may modulate disease severity; 20 patients were homozygous for ≥1 mutation or SNP. Patients had the following alleles associated with higher HbF synthesis: HBG2 rs7482144 C>T (Xmn1 site), C/T n=9, T/T n=1; BCL11A rs1427407 G>T, G/T n=8; BCL11A rs10189857 A>G, A/G n=16, G/G n=18; HMIP rs9399137 T>C, T/C n=9, C/C n=2. Three patients were heterozygous for single α-globin gene deletion (-α/αα) and 2 were heterozygous for α-globin gene triplication (αα/ααα). Median TSS was 3.65 (min - max 0.4 - 8.1).
TI was achieved by 23/27 (85%) evaluable patients; 4 patients with ≥ 12 months follow-up have been transfusion free for > 10 months but were not yet evaluable for TI (Figure). β-thalassemia genotype did not strongly correlate with TI (two-sided Fisher’s Exact Test, p-value = 0.78). Month 12 median (min - max) peripheral blood vector copy number (PB VCN) was 1.5 (0.2 - 5.0) c/dg in TI or transfusion-free patients (n=27) and 0.2 (0.2 - 0.4) c/dg in patients who did not achieve TI (n=4). The transfusion-free patient (β0/β0) with the lowest month 12 PB VCN was homozygous for T/T at rs7482144 (HBG2 Xmn1 site) and G/G at rs10189857 (BCL11A), and heterozygous for single α-globin gene deletion. Endogenous Hb (5.9 g/dL HbF + 0.2 g/dL HbA2) and gene therapy-derived HbAT87Q (4.4 g/dL) at month 12 enabled this patient to stop transfusions.
Tests of association of SNPs and mutations with TI were not significant; no p-value < 0.31 (chi-squared test). As only 4 patients did not achieve TI, the power to detect an association was limited. Larger sample sizes are needed to determine if individual SNPs and mutations may have an impact on TI.
In TI or transfusion-free patients (n=27), TSS correlated strongly with month 12 endogenous unsupported Hb (HbA + HbA2 + HbF + HbE without RBC transfusions for 60 days) (correlation coeff. = -0.76, p < 0.0001), but not with HbAT87Q (correlation coeff. = 0.26, p = 0.19) or unsupported total Hb (correlation coeff. = 0.32, p = 0.10).
Beti-cel-related adverse events (AE) in >1 patient were abdominal pain (n=2 non-β0/β0; n=1 β0/β0), thrombocytopenia (n=3 non-b0/b0). Serious AEs in ≥3 patients post-infusion were thrombocytopenia (n=2 non-β0/β0; n=1 β0/β0), pyrexia (n=1 non-b0/b0; n=2 β0/β0), veno-occlusive disease (n=3 non-β0/β0).
Summary
Genetic characterization of TDT patients treated with beti-cel revealed diverse HBB and non-HBB mutations and polymorphisms that may influence disease severity. Higher PB VCN and HbAT87Q levels were associated with increased likelihood of TI. In instances of lower HbAT87Q, higher endogenous HbF might be a determinant in whether TI is achieved. Despite genetic heterogeneity, beti-cel enabled patients to achieve TI regardless of β-thalassemia genotype, TSS, disease genetic modifiers including HBA, and HbF QTL SNP genotypes.
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Walters:Veevo Biomedicine: Consultancy; AllCells, Inc: Consultancy; Editas: Consultancy. Chui:bluebird bio, Inc.: Other: Payment for lab use for the sequencing analyses done for the studies. Lal:bluebird bio, Inc.: Research Funding; Agios Pharmaceuticals: Consultancy; Celgene, BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; La Jolla Pharmaceutical Company: Research Funding; Novartis: Research Funding; Protagonist Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Terumo Corporation: Research Funding; Chiesi USA: Consultancy; Insight Magnetics: Research Funding. Locatelli:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharmaceeutical: Speakers Bureau. Kwiatkowski:bluebird bio, Inc.: Consultancy, Research Funding; Agios: Consultancy; Apopharma: Research Funding; Bristol Myers Squibb: Consultancy; Imara: Consultancy; Celgene: Consultancy; Sangamo: Research Funding; Terumo Corp: Research Funding; Novartis: Research Funding. Porter:bluebird bio, Inc.: Consultancy, Honoraria; Vifor Pharmaceuticals: Honoraria; La Jolla Pharmaceuticals: Honoraria; Protagonist Therapeutics: Honoraria; Agios Pharmaceuticals: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Silence Therapeutics: Honoraria. Thuret:Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis pharma: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials. Kulozik:Novartis: Consultancy, Honoraria; bluebird bio, Inc.: Consultancy, Honoraria. Thrasher:4Bio Capital: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generation bio: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership; Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership. Yannaki:bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Speakers Bureau; SANDOZ: Speakers Bureau; Gilead: Speakers Bureau. Yang:bluebird bio,Inc.: Current Employment, Current equity holder in publicly-traded company. Whitney:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Petrusich:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Colvin:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Thompson:BMS: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; CRISPR/Vertex: Research Funding; Biomarin: Research Funding; Baxalta: Research Funding.
The article reports on a study to evaluate the safety and efficacy of gene therapy as a form of treatment for patients with transfusion-dependent ?-thalassemia. The results indicate that gene therapy ...with autologous CD34+ cells transduced with the BB305 vector reduced or eliminated the need for long-term red-cell transfusions among these patients.
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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.
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.
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 1Preliminary results of dosing parameters and transplantation outcomesSubjectAge (years) and GenderGenotypeBB305 Drug ProductDay of Neutrophil EngraftmentDrug Product- related Adverse EventsβA-T87Q-Hb at last follow-up visit /Total Hb (g/dL)VCNCD34+ cell dose(x106 per kg)110218 Fβ0/βE1.0/1.1a6.5Day +17None1.77/8.6110421 Fβ0/βE0.7/0.7a5.4PPP110620 Fβ0/β01.512.3PPPAs of 31 July 2014; P, pendingaIf 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.
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.
Background: Hematopoietic stem cell (HSC) gene transfer has the potential to induce globin production and mitigate or eliminate blood transfusions in patients with β-thalassemia major. Previously ...reported early results in subjects with β-thalassemia major participating in the ongoing HGB-205 and HGB-204 (Northstar) studies suggest that transplantation with autologous CD34+ cells transduced with a replication-defective, self-inactivating LentiGlobin BB305 lentiviral vector containing an engineered βA-T87Q-globin gene (LentiGlobin BB305 Drug Product) has a positive safety profile and leads to βA-T87Q globin production and can lead to transfusion independence. Here we provide an update on subjects treated with the LentiGlobin BB305 Drug Product in the Northstar study.
Subjects and Methods: HSCs from transfusion-dependent β-thalassemia major subjects are mobilized by a combination of G-CSF and plerixafor, collected via apheresis, and CD34+ cells are selected and transduced with LentiGlobin BB305 lentiviral vector to produce drug product. Subjects undergo myeloablation with busulfan before LentiGlobin BB305 Drug Product infusion. Subjects are monitored for hematologic recovery, vector copy number, βA-T87Q-globinexpression, adverse events, and transfusion requirements after drug product infusion. Integration site analysis (ISA) and replication-competent lentivirus (RCL) assays are performed as part of the safety monitoring.
Results: As of 31 July 2015, 10 subjects with transfusion-dependent β-thalassemia (β0/β0 n=5, β0/βE n=3, β0/β+ n=1, and 1 heterozygous β0 genotype) have been infused with drug product. Before enrollment, subjects had received a median of 170 ml/kg/year (range: 137 to 233 ml/kg/year) of red blood cell (RBC) transfusions. The median age of the subjects was 26 years (range: 18 to 35 years), with 8 females and 2 males, and subjects received a median of 7.9 x 106 CD34+ cells/kg (range: 5.3 to 15.0 x106/kg) with median vector copy number of 0.8 (range: 0.3 to 1.5 copies/diploid genome).
All subjects engrafted after drug product infusion; median time to engraftment was Day +17 (range +13 to +29) for neutrophils and Day +30 (range: +17 to +35) for platelets. The toxicity profile observed was consistent with autologous transplantation. To date, no ≥ Grade 3 drug-product-related adverse events have been observed, and there is no evidence of clonal dominance or replication competent lentivirus after a median follow-up of 198 days (range: 65 to 492 days) post-infusion. All subjects have detectable vector-derived HbAT87Q with a median peak level of 5.4 g/dL (range: 2.4 to 8.9 g/dL) ≥ 3 months post-infusion. The 7 subjects (3 β0/β0, 2 β0/βE, 1 β0/β+ and 1 heterozygous β0 genotype) monitored for at least 6 months post-infusion are making a median of 5.2 g/dL (range: 1.9 to 8.2 g/dL) of HbAT87Q with total Hb ranging from 8.5 to 11.1 g/dL at their last visit. Of these 7 subjects, 2 β0/β0 subjects have received a single RBC transfusion post-discharge, 1 β0/β0 subject remains transfusion dependent, and all 4 non-β0/β0 subjects have been RBC transfusion-free for ≥ 90 days (median 287 days of transfusion independence, range 171 to 396 days).
Conclusion: Ten subjects with β-thalassemia major in the Northstar study have been infused with LentiGlobin BB305 Drug Product without ≥ Grade 3 drug product-related adverse events or evidence of clonal dominance. To date, LentiGlobin derived HbAT87Q is detectable in all infused subjects leading to transfusion independence or reduction in transfusion needs in almost all subjects. Gene therapy with the LentiGlobin BB305 is a promising modality for the treatment of patients with β-thalassemia major.
Walters:ViaCord and AllCells, Inc: Other: Medical director. Kwiatkowski:ISIS: Membership on an entity's Board of Directors or advisory committees; Shire Pharmaceuticals and Sideris Pharmaceuticals: Consultancy; Sideris Pharmaceuticals: Consultancy; Novartis: Research Funding. Schiller:Sunesis: Honoraria, Research Funding. von Kalle:bluebird bio, Inc.: Consultancy. 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, Equity Ownership. Thompson:bluebird bio, Inc.: Consultancy, Research Funding.
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