Safety Study of a Dual Anti-HIV Gene Transfer Construct to Treat HIV-1 Infection

This is an early phase research study looking at whether an experimental gene transfer, LVsh5/C46 (also known as Cal-1), is safe and if it can protect the immune system from the effects of HIV without the use of antiretroviral drugs.

Cal-1 is an experimental gene transfer agent designed to inhibit HIV infection through 2 active parts:

1. Removing a protein named CCR5 from bone marrow and white blood cells
2. Producing a protein named C46 on bone marrow and white blood cells

It is estimated that 33 million individuals are currently infected with HIV. HIV/AIDS is a disease that impairs immune function, primarily by decreasing CD4+ T lymphocytes. The progression can be contained by daily dosing with antiretroviral therapy (ART) but there are side effects that can be treatment limiting, and the development of HIV drug resistance can force the physician to modify the ART regimen. There are no effective vaccines currently available for HIV.

LVsh5/C46 (also known as Cal-1) is a dual therapeutic, self-inactivating lentiviral vector that encodes for both a short hairpin RNA against the HIV-1 co-receptor CCR5 (sh5) and a HIV-1 fusion inhibitor, C46 and inhibits two processes required for HIV-1 infection:

1. Binding of the virus to the cellular CCR5 co-receptor and
2. Fusion of the virus with the host cell

The rationale is that Cal-1 introduced into hematopoietic progenitor/stem cells (HSPC) and mature CD4+ T lymphocytes will protect these cells and their progeny cells from HIV-1 infection and its pathogenic sequelae. This may provide a continuous means of controlling HIV-1 after a single or infrequent dose(s), thereby decreasing or delaying (partially or completely) the need for antiretroviral drug therapy.

• Drug: Busulfan
  Intravenous busulfan
  Other Name: Busulfex
• Biological: Cal-1 modified HSPC
  Hematopoietic progenitor/stem cells (HSPC) modified with LVsh5/C46 (Cal-1)
  Other Name: LVsh5/C46 modified HSPC
• Biological: Cal-1 modified CD4+ T lymphocytes
  CD4+ T lymphocytes modified with LVsh5/C46 (Cal-1)
  Other Name: LVsh5/C46 modified CD4+ T lymphocytes

• Experimental: No busulfan pre-conditioning
  Cal-1 modified HSPC and Cal-1 modified CD4+ T lymphocytes without busulfan preconditioning
  Interventions:

  • Biological: Cal-1 modified HSPC
  • Biological: Cal-1 modified CD4+ T lymphocytes
• Experimental: 1 x 4mg/kg busulfan preconditioning
  Cal-1 modified HSPC and Cal-1 modified CD4+ T lymphocytes, with single 4mg/kg busulfan dose administered as pre-conditioning for transplant
  Interventions:

  • Drug: Busulfan
  • Biological: Cal-1 modified HSPC
  • Biological: Cal-1 modified CD4+ T lymphocytes
• Experimental: 2 x 4mg/kg busulfan pre-conditioning
  Cal-1 modified HSPC and Cal-1 modified CD4+ T lymphocytes, with two 4mg/kg busulfan doses administered as pre-conditioning for transplant
  Interventions:

  • Drug: Busulfan
  • Biological: Cal-1 modified HSPC
  • Biological: Cal-1 modified CD4+ T lymphocytes

Inclusion Criteria:

• Prior to any study-related procedures, signed informed consent indicating that they understand the purpose, risks and procedures required for the study and are willing to participate in the study
• Individuals aged 18 to 65 years of age (inclusive) at time of consent
• Documented HIV-1 infection ≥ 6 months prior to Screening 1
• Previous treatment with antiretroviral agents that had a demonstrated suppressive effect (defined as plasma HIV RNA ≤ 50 copies/ml)
• A documented viable ART regimen option, as determined by the Investigator, taking into account prior ART experience and HIV geno/phenotyping analyses

• Not taking antiretroviral therapy for ≥ 6 weeks prior to Screening 1, for one or more of the following reasons:

  i) Concerns over short-term or long-term toxicities associated with antiretroviral agents, or ii) Treatment fatigue from the daily regimen of life-long therapy

• Plasma HIV-1 viral RNA ≥ 5,000 copies/mL and ≤ 100,000 copies/ml at Screening 1 and Screening 2
• CD4+ T lymphocyte count ≥ 500 cells/µl at Screening 1 and Screening 2

Exclusion Criteria:

• Abnormal hematology at Screening 1: Absolute neutrophil count (ANC) < 1.5 x 109/L, Platelet count < 100 x 109/L, Hemoglobin < 10 g/dL
• Abnormal biochemistry at Screening 1: Alanine aminotransferase (ALT) > 2.5 x Upper Limit of Normal (ULN), Total bilirubin > 1.5 x ULN, Serum creatinine > 1.5 x ULN
• Detection of any CXCR4-tropic HIV-1 at Screening 1
• Evidence of co-infection with hepatitis B virus, hepatitis C virus, West Nile Virus, or HTLV-1 as detected at Screening 2
• Evidence of active TB infection determined by positive QuantiFERON®-TB Gold/IGRA test result and clinical confirmation at Screening 2
• ART or other antiretroviral therapy within 6 weeks of Screening 1 or any time during the pre-infusion period
• Documented history of CD4+ T lymphocyte count < 250 cells/µl
• Any previous or current AIDS-defining illnesses (CDC Category C), including AIDS-related dementia, with the exception of Kaposi's sarcoma confined to the skin
• History of malignancy or systemic chemotherapy within the last 5 years (i.e., subjects with prior malignancy must be disease-free for 5 years), except curatively-treated basal cell carcinoma, cutaneous squamous cell carcinoma, or cervical or anal intra-epithelial neoplasia
• History of steroid-dependent asthma in the past 5 years
• History of seizure
• Any clinical history of hematologic diseases including leukemia, myelodysplasia, myeloproliferative disease, thromboembolic disease, sickle cell disorder, thrombocytopenia or leukopenia
• Class II-IV heart failure, according to the New York Heart Association classification
• Inadequate venous access for apheresis, as assessed at Screening 1
• Current or planned systemic immunosuppressive or immunomodulatory medication
• Taking warfarin, aspirin or any medication that is likely to affect platelet function or other aspects of blood coagulation, and unable to safely cease this medication for a period of 1 week prior, during, and 1 week after administration of G-CSF (a total period of 19 days)
• Participation in any study involving any investigational drug or medical device within 30 days prior to Screening 1
• Receipt of a vaccine for HIV-1 or any gene transfer product at any time
• Prior treatment with recombinant G-CSF or busulfan or other stem-cell mobilizing or modulating agent within the previous 12 months
• Known hypersensitivity to busulfan, G-CSF (Neupogen™) or E. coli-derived proteins
• Subjects who will not accept transfusions of blood products
• Pregnant or breast-feeding at any time between Screening 1 and Baseline (infusion)
• History of alcohol or drug abuse within the 12 months prior to Screening 1
• Inability to understand and provide informed consent