Novel NAALADase Inhibitor Technology to be Developed to Treat Neurodegenerative Diseases

[antiquity]

Guilford Pharmaceuticals Signs License Agreement With Pfizer


Novel NAALADase Inhibitor Technology to be Developed to

Treat Neurodegenerative Diseases

BALTIMORE, May 8 /PRNewswire-FirstCall/ -- Guilford Pharmaceuticals Inc. (Nasdaq:GLFD) announced today that it has entered into an exclusive license agreement with Pfizer for a novel class of potential drugs called NAALADase inhibitors that have been shown in preclinical testing to ameliorate certain central and peripheral neurodegenerative diseases, such as diabetic peripheral neuropathy and neuropathic pain.

Under the terms of the agreement, Pfizer will have exclusive rights to develop Guilford's NAALADase inhibitors worldwide, and will conduct and pay for all costs associated with research, development, manufacturing, and commercialization of any products that may emerge from this agreement. Guilford retains the right to continue to conduct and pay for the development of NAALADase inhibitors not under development by Pfizer for prostate cancer, head and spinal cord injury, and drug addiction. Pfizer has the exclusive right in the future to acquire, for certain consideration, any products developed by Guilford for these indications. In exchange, Pfizer has agreed to pay Guilford $15 million in cash, including $5 million at signing, and $10 million by March 31, 2004 (or earlier depending on whether a lead compound has been selected for clinical development). If Pfizer does not pay the additional $10 million on or before March 31, 2004, rights revert to Guilford at its election, along with data and other information generated by Pfizer relating to Guilford's NAALADase inhibitors.

As part of the agreement, Guilford is eligible to receive royalties on future product sales and milestone payments related to the successful development and commercialization of a NAALADase inhibitor. The schedule of milestone payments outlines a total of $42 million to be paid for each compound developed through commercialization, as well as one additional set of milestone payments totaling $20 million for an additional indication for the same compound.

"We are very pleased to license our NAALADase inhibitor program to Pfizer, the world's leading pharmaceutical company. Pfizer has a major commitment to the fields of central and peripheral nervous system disorders," commented Craig R. Smith, M.D., Chairman, President and Chief Executive Officer of Guilford. "Our agreement with Pfizer is consistent with Guilford's objective of finding the highest-quality strategic partnerships for the programs we intend to license, while continuing to advance select product development efforts in the US independently."

Guilford has one marketed product, GLIADEL(R) Wafer, which recently received FDA approval for an expanded indication for use in patients with newly diagnosed high-grade malignant glioma as an adjunct to surgery and radiation, and a pipeline which includes two product candidates, GPI 1485 and AQUAVAN(TM) Injection, in Phase II clinical testing.

NAALADase Inhibitor Program Background

NAALADase, or N-Acetylated-Alpha-Linked-Acidic-Dipeptidase, is a membrane- bound enzyme found principally in the central and peripheral nervous systems. NAALADase is believed to play a role in modulating the release of glutamate, one of the most common chemical messengers between nerves. During conditions of acute injury or chronic neurodegenerative disorders, there may be a large increase in glutamate release that incites a cascade of biochemical events, ultimately leading to cell injury and death.

Guilford has created several unique classes of NAALADase inhibitors and evaluated their potential therapeutic application in preclinical models of various acute and chronic neurodegenerative disorders, including diabetic peripheral neuropathy, neuropathic pain, Lou Gehrig's Disease (ALS), head and spinal cord trauma, and stroke. NAALADase is the same protein as prostate specific membrane antigen (PSMA), a protein found on the surface of prostate cancer cells. Guilford has also shown that its compounds may have utility for diagnostic or therapeutic purposes in prostate cancer.

In preclinical animal models of diabetic peripheral neuropathy and neuropathic pain, Guilford scientists have shown that treatment with a NAALADase inhibitor can normalize pain sensitivity, increase nerve conduction velocity and prevent or slow peripheral nerve degeneration.

Diabetic peripheral neuropathy is a debilitating and progressive disorder involving increased pain sensitivity, tingling, weakness and numbness in a patient's extremities. It is believed to affect approximately one million people in the United States.

Guilford has 37 issued US patents and 10 pending patent applications, and corresponding foreign counterparts protecting its NAALADase inhibitor technology.

About Guilford

Guilford Pharmaceuticals Inc. is a fully integrated pharmaceutical company engaged in the research, development and commercialization of products that target the hospital and neurology markets. Guilford's product pipeline includes a marketed product, GLIADEL(R) Wafer, for the treatment of brain cancer, and products in development for Parkinson's disease, peripheral nerve damage and anesthesia and sedation.

Contact: Guilford Pharmaceuticals Inc.

Stacey Jurchison 410.631.5022

Internet addresses: www.guilfordpharm.com

[Chris Chappell]

Good article, Seneca. Thx.

Progress - its a good thing.

[Wise Young]

So, here is all the you ever wanted to know but were afraid to ask. NAALADase stands for N-acetylated alpha-linked acidic dipeptidase. This mouthful of a name for an enzyme breaks down N-acetylaspartylglutamate (NAAG) which is a precursor of glutamate and an agonist for mGlu metatropic glutamate receptors. So, this enzyme increases the level of glutamate which acts on the NMDA receptor (a glutamate receptor) and reduces the levels of NAAG which acts on the mGlu receptor. Glutamate receptors have long been implicated as one of the mechanisms that signals cells to commit apoptosis (programmed cell death). Blockers of NAALADase therefore may protect against apoptosis in neurodegenerative diseases.

Attached are some relevant abstracts.

Wise.


• Cai Z, Lin S and Rhodes PG (2002). Neuroprotective effects of N-acetylaspartylglutamate in a neonatal rat model of hypoxia-ischemia. Eur J Pharmacol 437:139-45. Summary: Neuroprotective effects of N-acetylaspartylglutamate (NAAG), the precursor of glutamate and a selective agonist at the Group II metabotropic glutamate (mGlu) receptor, against hypoxic-ischemic brain injury were examined in a neonatal rat model of cerebral hypoxia-ischemia. The neonatal hypoxia-ischemia procedure (unilateral carotid artery ligation followed by exposure to an 8% oxygen hypoxic condition for 1.5 h) was performed in 7-day-old rat pups. Following unilateral carotid artery ligation, NAAG (0.5 to 20 mg/kg, i.p.) was administered before or after the hypoxic exposure. Brain injury was examined 1-week later by weight reduction in the ipsilateral brain and by neuron density in the hippocampal CA1 area. In the saline-treated rat, neonatal hypoxia-ischemia resulted in severe brain injury as indicated by a 24% reduction in the ipsilateral brain weight. Low doses of NAAG (2-10 mg/kg, but not 0.5 mg/kg), administered before or even if 1 h after the hypoxic exposure, greatly reduced hypoxia-ischemia-induced brain injury (3.8-14.2% reduction in the ipsilateral brain weight). A high dose of NAAG (20 mg/kg) was ineffective. While L(+)-2-Amino-4-phosphonobutyric acid (L-AP4) and trans-[1S,3R]-1-Amino-cyclopentane-1, 3-dicarboxylic acid (t-ACPD) were unable to provide protection against hypoxic-ischemic brain injury, 2-(phosphonomethyl) pentanedioic acid (2-PMPA), an inhibitor of N-acetylated alpha-linked acidic dipeptidase (NAALADase), which hydrolyzes endogenous NAAG into N-acetyl-aspartate and glutamate, significantly reduced neonatal hypoxia-ischemia-induced brain injury. (alphaS)-alpha-Amino-alpha-[(1S, 2S)-2-carboxycyclopropyl]-9H-xanthine-9-propanoic acid (LY341495), a selective antagonist at the mGlu2/3 receptor, prevented the neuroprotective effect of NAAG. Neuron density data measured in the hippocampal CA1 area confirmed that ipsilateral brain weight reduction was a valid measure for hypoxic-ischemic brain injury. Neonatal hypoxia-ischemia stimulated an elevation of cyclic AMP (cAMP) concentration in the saline-treated rat brain. NAAG, L-AP4 and t-ACPD all significantly decreased hypoxia-ischemia-induced elevation of cAMP. LY341495 blocked the effect of NAAG, but not of L-AP4 or t-ACPD, on hypoxia-ischemia-stimulated cAMP elevation. The overall results suggest that the neuroprotective effect of NAAG is largely associated with activation of mGlu2/3 receptor. Department of Pediatrics, Division of Newborn Medicine, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA. zcai@ped.umsmed.edu

• Gafurov B, Urazaev AK, Grossfeld RM and Lieberman EM (2001). N-acetylaspartylglutamate (NAAG) is the probable mediator of axon-to-glia signaling in the crayfish medial giant nerve fiber. Neuroscience 106:227-35. Summary: Glial cell hyperpolarization previously has been reported to be induced by high frequency stimulation or glutamate. We now report that it also is produced by the glutamate-containing dipeptide N-acetylaspartylglutamate (NAAG), by its non-hydrolyzable analog beta-NAAG, and by NAAG in the presence of 2-(phosphonomethyl)-pentanedioic acid (2-PMPA), a potent inhibitor of the NAAG degradative enzyme glutamate carboxypeptidase II. The results indicate that NAAG mimics the effect of nerve fiber stimulation on the glia. Although glutamate has a similar effect, the other presumed product of NAAG hydrolysis, N-acetylaspartate, is without effect on glial cell membrane potential, as is aspartylglutamate (in the presence of 2-PMPA). The hyperpolarization induced by stimulation, glutamate, NAAG, beta-NAAG, or NAAG plus 2-PMPA is completely blocked by the Group II metabotropic glutamate receptor antagonist (S)-alpha-ethylglutamate but is not altered by antagonists of Group I or III metabotropic glutamate receptors. The N-methyl-D-aspartate receptor antagonist MK801 reduces but does not eliminate the hyperpolarization generated by glutamate, NAAG or stimulation. These results, in combination with those of the preceding paper, are consistent with the premise that NAAG could be the primary axon-to-glia signaling agent. When the unstimulated nerve fiber is treated with cysteate, a glutamate reuptake blocker, there is a small hyperpolarization of the glial cell that can be substantially reduced by pretreatment with 2-PMPA before addition of cysteate. A similar effect of cysteate is seen during a 50 Hz/5 s stimulation. From these results we suggest that glutamate derived from NAAG hydrolysis appears in the periaxonal space under the conditions of these experiments and may contribute to the glial hyperpolarization. Department of Physiology, The Brody School of Medicine of East Carolina University, Greenville, NC 27858, USA.

• Thomas AG, Liu W, Olkowski JL, Tang Z, Lin Q, Lu XC and Slusher BS (2001). Neuroprotection mediated by glutamate carboxypeptidase II (NAALADase) inhibition requires TGF-beta. Eur J Pharmacol 430:33-40. Summary: Inhibition of glutamate carboxypeptidase (GCP) II (EC 3.4.17.21), also termed N-acetylated alpha-linked acidic dipeptidase (NAALADase), has been shown to protect against ischemic injury presumably via decreasing glutamate and increasing N-acetyl-aspartyl-glutamate (NAAG). NAAG is a potent and selective mGlu3 receptor agonist. Activation of glial mGlu3 receptors has been shown to protect against NMDA toxicity by releasing transforming growth factors, TGF-betas. We hypothesized that GCP II inhibition could be neuroprotective also via TGF-betas, due to increased NAAG. To verify this, Enzyme-Linked Immunosorbent Assays (ELISAs) were performed on media from both control and ischemic cultures treated with the GCP II inhibitor, 2-(phosphonomethyl)-pentanedioic acid (2-PMPA). We found that 2-PMPA attenuated ischemia-induced declines in TGF-beta. To further assess the role of TGF-betas in 2-PMPA-mediated neuroprotection, a neutralizing antibody to TGF-beta (TGF-beta Ab) was used. In both in vitro and in vivo models of cerebral ischemia, TGF-beta Ab reversed the neuroprotection by 2-PMPA. Antibodies to other growth factors had no effect. Data suggests that neuroprotection by GCP II inhibition may be partially mediated by promoting TGF-beta release. Guilford Pharmaceuticals Inc., 6611 Tributary Street, Baltimore, MD 21224, USA.

• Zhang W, Slusher B, Murakawa Y, Wozniak KM, Tsukamoto T, Jackson PF and Sima AA (2002). GCPII (NAALADase) inhibition prevents long-term diabetic neuropathy in type 1 diabetic BB/Wor rats. J Neurol Sci 194:21-8. Summary: AIMS/HYPOTHESIS: Hyperglutamatergic activity induced by ischemia is believed to underlie neuronal damage in a variety of neurological disorders, including neuropathic pain. Since ischemia is believed to be a prominent mechanism involved in diabetic polyneuropathy (DPN), we investigated the effect of the glutamate carboxypeptidase II (GCPII, EC #3.4-17.21; previously termed NAALADase), an enzyme responsible for the hydrolysis of the neuropeptide NAAG to NAA and glutamate, on the development of DPN in type 1 diabetic BB/Wor rats. METHODS: Diabetic animals were treated with 10 mg/kg/day i.p. of the selective GCPII inhibitor GPI-5232 from onset of diabetes for 6 months. Hyperalgesia to thermal stimulation and nerve conduction velocity (NCV) were measured monthly. The effect on structural DPN was assessed by scoring of single, teased myelinated fibers, myelinated fiber morphometry and ultrastructural examination of C-fibers at 6 months. RESULTS: GCPII inhibition showed significant but partial effects on hyperalgesia (p<0.001), nerve conduction slowing [p<0.01) axonal and nodal structural changes [p<0.001), small myelinated fiber atrophy, and degenerative changes of C-fibers. CONCLUSIONS: GCPII inhibition has beneficial effects on hyperalgesia, nerve function, and structural degenerative changes in DPN, which are likely mediated by inhibition of ischemia-induced glutamate release. Department of Pathology, Wayne State University, 540 E. Canfield Ave, Detroit, MI 48201, USA.