Hematopoietic Stem Cell Transplantation Gene Therapy for Treatment of Severe Hemophilia A

Eligible subjects will undergo CD34+ hematopoietic stem cell collection. These cells will be transduced ex vivo with CD68-ET3 lentiviral vector and subsequently, following a conditioning regimen of busulfan and anti-thymocyte globulin, the transduced cells will be infused to patients. After completion of study treatment, patients are followed up periodically for up to 15 years.

Inclusion criteria

• Able to provide informed consent for the protocol approved by the Institutional Review Board.
• Male subjects who are >= 18 years of age.
• Diagnosis of severe hemophilia A (<1 IU/dL factor VIII activity) based on one-stage coagulation assay.
• Documented history of more than 150 days of factor VIII treatment.
• Average of at least 4 bleeds requiring treatment per year over the prior three years, or at least 4 bleeds per year during the 3 years preceding the initiation of prophylaxis, or evidence of joint damage (knee, elbow or ankle) on physical or radiographic examination thought to be related to hemophilia.
• Performance status (Karnofsky score) of at least 70.
• Willingness to use effective barrier contraception or limit sexual intercourse to postmenopausal, surgically sterilized, or contraception-practicing partners, for 12 weeks (3 months) after transplantation.
• Willing and able to comply with the requirements of the protocol.

Exclusion criteria

• History of spontaneous central nervous system bleeding within the last 5 years.
• Significant functional deficits in major organs which would interfere with successful outcome following autologous stem cell transplant, the following guidelines will be utilized:

• Cardiac: There should be no evidence of significant cardiac dysfunction (resting left ventricular ejection fraction of < 50%) and no marked cardiomegaly. There should not be uncontrollable hypertension.
• Renal: GFR < 60 mL/min/1.73m2 per local institutional standard such as CKD-EPI creatinine equation or equivalent.
• Hepatic: There should be no evidence of hepatic dysfunction which is defined as a serum total bilirubin of > 1.5 mg/dL and AST/ALT > 3X the upper limit of normal.
• Hematologic: Absolute neutrophil counts (ANC) <1000/ µL or platelets counts < 150,000/µL.
• Pulmonary function with a corrected carbon monoxide diffusing capacity (cDLCO) < 50% predicted.
• History of a fVIII inhibitor (> 0.4 Bethesda Units/mL) including at least 2 measurements done at least a week apart or any single titer > 5 BU/mL.
• Subjects who have had prior cellular based therapy or gene editing/ gene therapy including a previous stem cell transplant.
• Subjects with any evidence of active infection or any immunosuppressive disorder, including currently detectable HIV viral load
• Subjects who are RPR, anti-HTLV-1 and II antibody, CMV PCR, VZV antibody and HSV PCR positive at screening.
• Subjects who have allergic reactions or hypersensitivity to any of the drugs used in the study (i.e., anti-thymocyte globulin, plerixafor, G-CSF, busulfan, levetiracetam) or to the constituents of the investigational product formulation.
• Evidence of hepatitis B active infection or chronic carrier based on a positive Hepatitis B DNA testing at screening.
• Positive (detectable viral load per local institutional standard) for the presence of Hepatitis C virus (HCV). Subjects who are positive for anti-HCV antibody are eligible as long as they have a negative undetectable HCV viral load at screening.
• Subjects diagnosed with any history of clinically relevant coagulation or bleeding disorder other than hemophilia A.
• Use of medication(s) that can affect hemostasis (e.g. aspirin, ibuprofen and non-COX-2 selective non-steroid anti-inflammatory drugs).
• Subjects with a history of a malignancy (except surgically resected non-melanoma skin cancer) or subjects with a family history of a known cancer syndrome in a first degree relative.
• Planned surgery within 6 months of enrollment (other than study procedures).
• Treatment with any live vaccines or systemic immunosuppressive agents, not including corticosteroids within 30 days before CD68-ET3-LV CD34+ infusion.
• Treatment with any investigational product within 30 days or 5 half-lives of the investigational product (whichever is longer) prior to enrollment.
• History of autoimmune disease (e.g., inflammatory bowel disease, systemic lupus erythematosus, vasculitis).
• Concurrent enrollment in another clinical study, which might interfere with the requirements of this study or have the potential to impact the evaluation of safety and efficacy of CD68-ET3-LV CD34+- unless it is a non-interventional observational study.
• Any condition in the opinion of the Study Investigators that will negatively impact the subject's ability to safely undergo an autologous stem cell transplant.
• Any reason in the opinion of the Study Investigators that will negatively impact the subject's ability to complete the clinical trial per the trial protocol.