Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector – Bacterium or component thereof or substance produced by said...
Reexamination Certificate
2001-08-03
2002-12-31
Low, Christopher S. F. (Department: 1653)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
Bacterium or component thereof or substance produced by said...
C514S002600, C514S012200, C530S350000, C530S412000, C435S068100, C435S069100, C435S070100, C435S320100, C435S325000, C435S252300, C536S023100
Reexamination Certificate
active
06500436
ABSTRACT:
BACKGROUND
The present invention relates to compositions and methods for treating pain, including bone tumor pain. In particular, the present invention relates to Clostridial toxin derivatives, methods for making the Clostridial toxin derivatives, and methods for treating pain using the Clostridial toxin derivatives.
Many, if not most, aliments of the body cause pain. The causes of pain can include inflammation, muscle spasm and the onset of a neuropathic event or syndrome. Inflammatory pain can occur when tissue is damaged, as can result from surgery or due to an adverse physical, chemical, or thermal event or to infection by a biologic agent. Spasticity or muscle spasm can be a serious complication of trauma to the spinal cord or other disorders that create damage within the spinal cord. Muscle spasm is often accompanied by pain. The pain experienced during a muscle spasm can result from the direct effect of the muscle spasm stimulating mechanosensitive pain receptors or from the indirect effect of the spasm compressing blood vessels and causing ischemia. Since the spasm increases the rate of metabolism in the affected muscle tissue, the relative ischemia becomes greater creating thereby conditions for the release of pain inducing substances. Neuropathic pain is a persistent or chronic pain syndrome that can result from damage to the nervous system, the peripheral nerves, the dorsal root ganglion or dorsal root, or to the central nervous system.
Neuropathic pain syndromes include allodynia, various neuralgias such as post herpetic neuralgia and trigeminal neuralgia, phantom pain, and complex regional pain syndromes, such as reflex sympathetic dystrophy and causalgia. Causalgia is characterized by spontaneous burning pain combined with hyperalgesia and allodynia.
Pain can be experienced when the free nerve endings which constitute the pain receptors in the skin as well as in certain internal tissues are subjected to mechanical, thermal, or chemical stimuli. The pain receptors transmit signals along afferent neurons into the central nervous system and thence to the brain.
The transduction of sensory signals, such as pain signals, from the periphery to sensation itself is achieved by a multi-neuronal pathway and the information processing centers of the brain. The first nerve cells of the pathway involved in the transmission of sensory stimuli are called primary sensory afferents. The cell bodies for the primary sensory afferents from the head and some of the internal organs reside in various ganglia associated with the cranial nerves, particularly the trigeminal nuclei and the nucleus of the solitary tract. The cell bodies for the primary sensory afferents for the remainder of the body lie in the dorsal root ganglia of the spinal column. The primary sensory afferents and their processes have been classified histologically; the cell bodies fall into two classes: (1) A-types, and (2) B-types. The cell bodies of A-types are relatively large (60-120 micrometer in diameter) while the cell bodies of B-types are smaller (14-30 micrometer) and more numerous. Similarly the processes fall into two categories: (1) C-fibers, and (2) A-fibers. C-fibers lack the myelin sheath that A-fibers possess. A-fibers can be further sub-divided into A beta-fibers, that are large diameters with well developed myelin, and A delta-fibers, that are thinner with less well developed myelin. It is generally believed that A beta-fibers arise from A-type cell bodies and that A delta- and C-fibers arise from B-type cell bodies.
After the activation of the primary sensory afferents the next step in the transduction of sensory signals is the activation of the projection neurons, which carry the signal, via the spinothalamic tract, to higher parts of the central nervous system such as the thalamic nuclei. The cell bodies of these neurons (other than those related to the cranial nerves) are located in the dorsal horn of the spinal cord. This is also where the synapses between the primary afferents and the projection neurons are located. The dorsal horn is organized into a series of laminae that are stacked, with lamina I being most dorsal followed by lamina II, etc. The different classes of primary afferents make synapses in different laminae. For cutaneous primary afferents, C-fibers make synapses in laminae I and II, A delta-fibers in laminae I, II, and V, and A beta-fibers in laminae III, IV, and V. Deeper laminae (V-VII, X) are thought to be involved in the sensory pathways arriving from deeper tissues such as muscles and the viscera.
The predominant neurotransmitters at the synapses between primary afferents and projection neurons are substance P, glutamate, calcitonin-gene related peptide (CGRP), and neuropeptide Y. The efficiency of transmission of these synapses can be altered via descending pathways and by local intemeurons in the spinal cord. These modulatory neurons release a number of mediators that are either inhibitory (e.g. opioid peptides, glycine) or excitatory (e.g. nitric oxide, cholecystokinin), to provide a mechanism for enhancing or reducing awareness of sensations.
Effective pain alleviating drugs are needed. It is known that intraspinal administration of opioids, such as morphine and fentanyl can alleviate pain. See e.g. Gianno, J., et al.,
Intrathecal Drug Therapy for Spasticity and Pain,
Springer-Verlag (1996) (which publication is incorporated herein by reference in its entirety). Unfortunately, current drugs used in intraspinal, or intrathecal, injections typically have only short lived antinociceptive effects. As a result, these drugs have to be frequently administered, such as by the aid of a pump for continuous infusion. For example, one frequently used pump is the SynchroMed® Infusion System, a programmable, implanted pump available from Medtronic, Inc., of Minneapolis, Minn. However, complications can arise due to the required surgical implantation procedure for the use of the pump and the known intrathecally administered drugs for pain, such as opioids, have the disadvantages of dependency and potential respiratory depression.
Longer acting analgesics are also known, for example, blocks by phenol injection. However, such treatments raise a considerable risk of irreversible functional impairment.
Intrathecal administration of botulinum toxin type B to mice to treat thermal hyperalgesia is known.
Br. J. Pharmacol
1999;127(2):449-456. Additionally, it has been reported (
Science,
1999; 286:1558-1561) (“Nichols et al.”) that intrathecal injection of a cytotoxic saporin-substance P (saporin can be abbreviated as “SAP” and substance P can be abbreviated as “SP”) conjugate (which can be abbreviated as SAP-SP) results in a reduction of thermal hyperalgesia and mechanical allodynia.
As discussed Nichols et al, supra, spinothalamic and spinoparabrachial neurons are involved in the ascending conduction of acute noxious stimuli. Apparently, these neurons are projection neurons can be targeted by substance P. When a conjugate of the ribosome-inactivating protein saporin and SP was intrathecally infused into the spinal cord, the SAP-SP conjugate is stated to have specifically concentrated in the projection neurons, apparently because these neurons express cell surface receptors for substance P (a substance P receptor can be abbreviated as “SPR”). Unfortunately, the SAP-SP targeted neurons are killed by the SAP.
Although SAP-SP is specific for projection neurons because projection neurons appear to express the SPR, an intrathecal injection of SAP-SP may cause necrosis of other neurons through non-specific or low affinity SAP-SP neuronal interactions. For example, SAP-SP may interact with and cause motor neurons cell death. Since motor neurons and most other neurons in the spinal cord do not regenerate, it is contraindicated to use SAP-SP in humans, unless destruction of the neurons with the resulting in permanent disablement, and for example, paralysis, is a desired end result. Clearly it would be desirable to be able to treat pain, including chronic pain, without causing necrosis and irrev
Allergan Inc.
Baran Robert J.
Fisher Carlos
Kam Chih-Min
Low Christopher S. F.
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