Drug – bio-affecting and body treating compositions – Whole live micro-organism – cell – or virus containing – Genetically modified micro-organism – cell – or virus
Reexamination Certificate
1999-06-26
2001-10-30
Clark, Deborah J. R. (Department: 1633)
Drug, bio-affecting and body treating compositions
Whole live micro-organism, cell, or virus containing
Genetically modified micro-organism, cell, or virus
C435S320100, C435S235100, C536S023200, C536S023500, C424S093600, C514S04400A
Reexamination Certificate
active
06309634
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to efficient delivery of viral vectors to the CNS. More particularly, the present invention relates to gene therapy for the treatment of central nervous system (CNS) disorders, particularly those disorders which involve the neurotransmitter dopamine.
BACKGROUND OF THE INVENTION
CNS disorders are major public health issues. Parkinson's disease (PD) alone affects over 1 million people in the United States. Clinically, PD is characterized by a decrease in spontaneous movements, gait difficulty, postural instability, rigidity and tremor. Parkinson's disease is caused by the degeneration of the pigmented neurons in the substantia nigra of the brain, resulting in decreased dopamine availability. Altered dopamine metabolism has also been implicated in schizophrenic patients who show increased dopamine in certain areas of the brain.
Currently, many CNS disorders such as PD are treated by systemic administration of a therapeutic agent. Systemic administration, however, is often inefficient because of a drug's inability to pass through the blood brain barrier and because many drugs cause peripheral side effects. Thus, many potentially useful compounds, such as proteins, cannot be administered systemically. If these compounds are successful in penetrating the blood-brain-barrier, they may also induce central nervous system side effects as well. Treatment of PD currently involves oral administration of the dopamine-precursor, L-dopa often in combination with a compound such ascarbidopa, a peripheral inhibitor of the enzyme aromatic amino acid decarboxylase (AADC) that decarboxylates dopa to dopamine. In the majority of patients, however, production of AADC in the affected brain regions is reduced as PD progresses and, consequently, larger and larger doses of L-dopa are required, leaving the patients with reduced therapeutic benefits and increased side effects.
In view of the limitations of current systemic therapies, gene delivery is a promising method for the treatment for CNS disorders such as PD. A number of viral based systems for gene transfer purposes have been described, such as retroviral systems which are currently the most widely used viral vector systems for this purpose. For descriptions of various retroviral systems, see, e.g., U.S. Pat. No. 5,219,740; Miller and Rosman (1989)
BioTechniques
7:980-990; Miller, A.D. (1990)
Human Gene Therapy
1:5-14; Scarpa et al. (1991)
Virology
180:849-852; Burns et al. (1993)
Proc. Natl. Acad. Sci. USA
90:8033-8037; and Boris-Lawrie and Temin (1993)
Cur. Opin. Genet. Develop
. 3:102-109.
Adeno-associated virus (AAV) systems are emerging as the leading candidates for use in gene therapy. AAV is a helper-dependent DNA parvovirus which belongs to the genus Dependovirus. AAV requires infection with an unrelated helper virus, either adenovirus, a herpesvirus or vaccinia, in order for a productive infection to occur. The helper virus supplies accessory functions that are necessary for most steps in AAV replication. For a review of AAV, see, e.g., Berns and Bohenzky (1987)
Advances in Virus Research
(Academic Press, Inc.) 32:243-307.
AAV infects a broad range of tissue, and has not elicited the cytotoxic effects and adverse immune reactions in animal models that have been seen with other viral vectors. (see, e.g., Muzyczka, (1992)
Current Topics in Microbiol. and Immunol
. 158:97-129; Flotte et al. (1993)
PNAS USA
90:10613-10617; Kass-eiser et al. (1992)
Gene Therapy
1:395-402; Yange et al.
PNAS USA
91:4407-4411; Conrad et al. (1996)
Gene Therapy
3:658-668; Yang et al. (1996)
Gene Therapy
3:137-144; Brynes et al. (1996)
J. Neurosci
. 16:3045-3055). Because it can transduce nondividing tissue, AAV may be well adapted for delivering genes to the central nervous system (CNS). U.S. Pat. No. 5,677,158 described methods of making AAV vectors. AAV vectors containing therapeutic genes under the control of the cytomegalovirus (CMV) promoter have been shown to transduce mammalian brain and to have functional effects in models of disease.
AAV vectors carrying transgenes have been described, for example, in Kaplitt et al. (1994)
Nature Genetics
8:148-153; WO 95/28493 published Oct. 26, 1995; WO 95/34670, published Dec. 21, 1995; During et al., (1998)
Gene Therapy
5:820-827; Mandel et al. (1998)
J. Neurosci
. 18:4271-4284; Szczypka et al. (1 999)
Neuron
22:167-178.). However, delivery of AAV vectors to the CNS has proven difficult. AAV has been used to transfer the thymidine (tk) kinase gene to experimental gliomas in mice, and the ability of AAV-tk to render these brain tumors sensitive to the cytocidal effects of ganciclovir has been demonstrated. Okada et al. (1996)
Gene Therapy
3:959-964; Mizuno et al. (1998)
Jpn. J. Cancer Res
. 89:76-80. Infusion of an AAV-CMV vector containing the human tyrosine hydroxylase (TH) gene, an enzyme involved in conversion of the amino acid tyrosine to dopa, into adult rat brain resulted in transduction of both neurons and glia (Kaplitt et al. (1995) VIRAL VECTORS, GENE THERAPY AND NEUROSCIENCE APPLICATIONS, Kaplitt and Loewy eds., 12:193-210, Academic Press, San Diego; Bankiewicz et al. (1997)
Exper. Neurol
. 144:147-156). Delivery of the same vector to monkey striatum resulted in robust expression of TH for up to 2.5 months (During et al., supra). Furthermore, AAV-CMV-TH was tested in a rodent model of Parkinson's Disease where it caused significant improvement in rotational behavior of 6-hydroxydopamine-lesioned rats (Fan et al. (1998)
Human Gene Therapy
9:2527-2537; Mandel et al. (1997)
PNAS USA
94:14083-14088).
However, while reports such as these demonstrate AAV's potential for targeting the CNS, they also demonstrate that direct injection of AAV vectors into the CNS results in limited numbers of transfected cells and that the transfected cells are clustered in a narrow area near the injection tracts. (see, e.g., During et al, supra; Fan et al., supra). Since multiple injections into the CNS cause undesirable complications, there remains a need for methods of delivering AAV vectors to larger areas of the brain using the least number of injection sites. In addition, the relationship between dose of injected vector and its resulting distribution in brain tissue has not been previously reported.
Furthermore, gene therapy of PD has focused on delivery of at least two genes encoding enzymes involved in dopamine synthesis, namely TH and AADC. These methods are subject to all of the delivery problems discussed above and, in addition, require that both genes are expressed in the proper amounts. Thus, treatment of PD using AAV-AADC in combination with L-dopa has also not been demonstrated.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides methods for delivering recombinant AAV (rAAV) virions carrying a transgene to the central nervous system (CNS) of a subject, for example a human, using convection-enhanced delivery (CED). CED can be conducted, for example, using either an osmotic pump or an infusion pump. In a preferred embodiment, the transgene encodes an aromatic amino acid decarboxylase (AADC) or active fragment thereof. When the transgene encodes an AADC, it is preferable to administer the rAAV virions into the striatum of the CNS.
In another aspect, the invention provides for methods for delivering recombinant AAV virions to a subject having a CNS disorder. The rAAV virions encode a suitable therapeutic polypeptide and are administered into the CNS of the subject using CED. In a preferred embodiment, the CNS disorder is Parkinson's disease (PD), the rAAV virions are administered into the striatum of the CNS, and the nucleic acid sequence encodes AADC.
In another aspect, methods for treating a neurodegenerative disease in a subject are provided. A preparation of recombinant adeno-associated virus (rAAV) virions carrying a therapeutic nucleic acid sequence that is expressible in transduced cells is administered to the CNS using convection-enhanced delivery (CED). In one embodi
Bankiewicz Krys
Cunningham Janet
Avigen, Inc.
Chen Shin-Lin
Clark Deborah J. R.
Robins & Pasternak LLP
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