Viral Vector Technology for Gene Therapy

Getting to the Root Cause of Disease
Gene therapy is the treatment of hereditary or infectious diseases by repairing or re-engineering the genome. The therapy’s goal is to treat the genetic cause of disease rather than merely treating the symptoms. The advantage of gene therapy over traditional treatments is the elimination or reduction of the toxic side effects that are commonly seen with drugs. Examples of diseases caused by genetic flaws include cancer (genetic flaws in genes that control cell growth), Parkinson’s disease (genetic flaw in a critical neuronal gene) and infectious disease (foreign genetic material invades human cells; i.e. HIV, and HCV).

Solving the Delivery Challenge
The field of gene therapy holds great promise, however, most of these promises have been unfulfilled due to challenges in developing a transport system capable of delivering genetic and therapeutic payloads into targeted cells efficiently, reproducibly, and permanently.

Vectors are vehicles that deliver genetic material into cells. Viral vectors use the backbone of viruses for this purpose. Viruses are very effective at getting into cells, so the first challenge is to remove the disease-causing elements from the virus and leave behind a natural delivery vehicle. VIRxSYS’s HIV-based lentiviral vector platform has achieved this goal and has also overcome other existing challenges, such as high-efficiency gene transfer, stable transfer of genetic material into dividing and non-dividing cells, and a reduced risk of immunogenicity and insertional oncogenesis (cancer). VIRxSYS created VRX496 for the first application of our vector against the target disease, HIV/AIDS. To see how VIRxSYS is using gene therapy to treat HIV click here to view an animation.

VRX496 is created by removing the disease components of HIV and inserting an anti-HIV therapeutic payload, called antisense. The Company has demonstrated that such a vector can inhibit HIV replication by more than 99% (Humeau 2004).

HIV infects human cells very efficiently and, consequently, a vector derived from HIV has these remarkable properties for efficient gene delivery. VIRxSYS has demonstrated that its HIV lentiviral vector can deliver therapeutic payloads into human cells with greater than 90% efficiency, which is remarkable compared with other gene therapy vectors that have reported an efficiency of 20-50%. VIRxSYS’ vector efficiency can be achieved in several important human hematopoietic cell types such as lymphocytes, hematopoietic CD34+ cells, monocyte-derived dendritic cells, and a panel of tumor cell lines.

VIRxSYS is the only company currently testing a lentiviral vector permitted for use by the FDA in Phase II clinical trials. To date, patients in the Company’s clinical trials have experienced no adverse events due to treatment, thus supporting the safety of the Company’s vector for applications in humans.

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Intellectual Property

VIRxSYS has developed an extensive portfolio of intellectual property which is protected by a combination of patents, trade secrets, and trademark law. Below is a summary of the Company’s parent patents in the United States.  VIRxSYS also has many foreign counterparts in countries around the world.

Patent/Ser No. Issue / Publication Date Title
US 5,885,806 March 23, 1999 Methods to Prepare Conditionally Replicating Viral Vectors
US 6,114,141 September 5, 2000 Method to Express Genes from Viral Vectors
09/667,893 Filed September 22, 2000 Conditionally Replicating Vectors and Methods for Their Production and Use
US 6,168,953 January 2, 2001 Genetic Antiviral Agents and Methods for Their Use
US 6,207,426 March 27, 2001 Conditionally Replicating Viral Vectors and their Use
US 6,410,257 June 25, 2002 Method to Express Genes from Viral Vectors
US 6,498,033 December 24, 2002 Lentiviral Vectors
US 6,627,442 September 30, 2003 Methods for a Stable Transduction of Cells with HIV-Derived Viral Vectors
US 20040203017 October 14, 2004 High-Throughput Methods for Identifying Gene Function using Lentiviral Vectors
US 6,835,568 December 28, 2004 Regulated Nucleic Acid Expression System
US 20050123514 June 9, 2005 Increased Transduction Using ABC Transporter Substrates and/or Inhibitors
US 20060003452 June 30, 2005 Vector Packaging Cell Line
US 20050196381 September 8, 2005 Two-vector Complementary Systems for Generating Immune Responses
11/424,673 Filed October 20, 2005 Antibody Complexes
US 20050257277 November 17, 2005 Regulation of Transcription with a Cis-acting Ribozyme
10/587,437 Filed May 22, 2006 Transduction of Primary Cells
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Manufacturing Facilities

VIRxSYS is the only company currently testing a lentiviral vector permitted for use by the FDA in Phase II clinical trials. Consequently, VIRxSYS is uniquely positioned to manufacture clinical-grade lentiviral vectors for therapies treating a wide range of life-threatening diseases.

VIRxSYS is initially focused on using lentiviral vectors in cellular therapies for HIV/AIDS.

VIRxSYS both manufactures clinical grade lentiviral vectors and performs cell processing for clinical trials at its Gaithersburg, Maryland facility. Our manufacturing facility includes two class 10,000 clean rooms for vector reproduction and patient cell processing. In addition, the company has a dedicated plasmid production room, a suite of quality control labs, and a variety of support rooms.

In addition to our manufacturing facilities, VIRxSYS has extensive research and devlopment facilites and capabilities dedicated to supporting the manufacturing and cinical trial initiatives, as well as to developing a pipeline of therapies for additional disease indications.

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