DESCRIPTION
This invention relates to a pharmaceutical
composition for treating glioblestoma.
Technical Field
The present: invention relates to a novel
pharmaceutical use of a compound having an antagonistic
action against AMPA receptor as a therapeutic agent for
glioblastoma.
Background of the Invention
Glioma is the general name of tumors originating
from ependymoblasts, which is the stem cell for glia, in
the course of the differentiation thereof into ependymal
cell, astroglia and oligodendroglia [Seikagaku Jiten
(Dictionary of Biochemistry), the third edition, Tokyo
Kagaku Dojin, Tokyo, 1998].
Glioblastoms multiforme (referred to as glioblastoma
hereinafter) highly invades the central nervous system and
is ranked at a higher malignancy level among gliomas.
Thus, glioblastoma is a typical one of malignant brain
tumors.
Additionally, the lethal rate thereof is very high
so that the onset thereof induces death in 9 to 12 months.
Even today with the progress in the various therapeutic
methods thereof, the 5-year survival from 1986 to 1990 is
8.0%, compared with the 5-year survival 20 years ago namely
the 5-year survival from 1969 to 1975, which was 11.9%.
Thus, almost no difference is observed (Neurology Progress,
43(3), 338-350, 1999). Accordingly, it is strongly desired
that an effective therapeutic method thereof should be
established.
Tumor cells of glioblastoma are the most
undifferentiated among brain tumors, so the tumor cells
have high potentials of migration and proliferation and are
highly invasive, leading to very poor prognosis.
Glioblastoma is classified into primary glioblastoma
de novo and secondary glioblastoma, depending on the
difference in the gene mechanism of the malignant
transformation of undifferentiated astrocyte or precursor
cells. Secondary glioblastoma occurs in a young generation
of 45 years old or younger. In 4 to 5 years on average,
secondary glioblastoma occurs from astrocytoma through
undifferentiated astrocytoma. Meanwhile, primary
glioblastoma de novo frequently occurs in an older
generation of the mean age of 55 years old. Generally,
primary glioblastoma de novo takes the form of fulminant
glioblastoma (referred to as de novo glioblastoma as well)
which occurs within 3 months from the state with no
clinical or pathological abnormalities [Pathology and
Genetics of the Nervous Systems. 29-39 (IARC Press, Lyon,
France, 2000)].
Glioblastoma migrates along myelinated nerve and
spreads widely in the central nerve. Therefore, surgical
treatment thereof cannot show any satisfactory therapeutic
effect (Neurol. Med. Chir. (Tokyo) 34, 91-94, 1994; Neurol.
Med. Chir. (Tokyo) 33, 425-458, 1993; Neuropathology 17,
186-188, 1997). Additionally, pharmaceutical agents with
an indication for glioblastoma are limited in Japan to for
example ranimustine and interferon. Additionally, the
efficacy thereof is insufficient.
a-amino-3-hydroxy-5-methyl-4-isoxazole propionic
acid (AMPA)-type glutamate receptors belong to ionotropic
glutamate receptors are responsible for rapid nerve
conduction of almost all excitatory synapses (Trends
Neurosci. 16, 359-365, 1993; Annu. Rev. Neurosci. 17, 31-
108, 1994; Prog. Neurobiol. 54, 581-618, 1998). AMPA
receptors are expressed in many glyacytes like those in
neurons (Trends Pharmacol. Sci. 21, 252-258, 2000). AMPA
receptors are composed of four subunits, namely GluRl
through GluR4. The Ca2+ permeability of an AMPA receptor
depends on the composition with the subunits thereof.
Specifically, an AMPA receptor with the GluR2 subunit has
low Ca2+ permeability, while an AMPA receptor without GluR2
has high Ca2+ permeability. A higher content of the GluR2
subunit decreases the Ca2+ permeability more (Trends
Neurosci. 16, 359-365, 1993; Annu. Rev. Neurosci. 17, 31-
108, 1994; Prog. Neurobiol. 54, 581-618, 1998). Further,
the unique feature of GluR2 is deserted as foHows. In case that one amino acid
residue in the second hydrophobe region (M2), which is originally arginine ( R),
is substituted with gjutamine (Q), the resulting homomer receptor composed of
the substituted GkiR2 (Q) has high Ca* permeability (Trends Neurosci. 16,359-
365, 1993, Annu. Rev. Neurosci. 17, 31-108, 1994). In other words, such
receptor at a higher content of the 6iuR2 subunlt when the subunit is GkiR (Q)
type is highly permeable to Ca2*. When the subunit is GkiR2 (R), however, the
resulting receptor does not shows any Ca2+ permeability.
Concerning giioma cells and gkitamate, reports showed that the expression of
the GluR2 gene is low in C6-gKoma (J. Neurosci. Res. 46,164-178, 1996) and
that 66% of gNoblastoma culture cells respond to a gkitamate receptor against
and depolarize (Eur. J. Neurosci. 10,2153-2162,1998).
The following reports have been issued about the inhibiting action of antagonists
against the ionotropic gkitamate receptor family on giioma and the like.
1) Document WO 00/24395 discloses an invention relating to the method for
inhibiting the interaction between AHPA receptor complexes and
gkitamate for cancer treatment, wherein specific examples of brain tumor
include meduMoblastoma classified as a fetal tumor and human brain
astrocytoma as one giioma type. The Reference describes
the in vitro effect of an antagonist GYK152446 against AMPA
receptor on brain astrocytoma.
However, the reference does not disclose or suggests
the use of the antagonist against AMPA receptor for
treatment of glioblastoma with high malignancy to have
resistance to radiotherapy or chemotherapy.
,'* 2) Non-patent reference 1 by the inventor
described above includes a description that antagonists
against NMDA- and AMPA receptors are highly sensitive to
tumor cells derived from peripheral cells but poorly
sensitive to tumor cells derived from nerve and glyacites.
Additionally, the reference describes that these
antagonists are useful as therapeutic agents of peripheral
cancer. Thus, the effect of the invention on glioblastoma
cannot be anticipated on the basis of the in vitro effect
using the tumor cells with lower malignancy levels than
that of glioblastoma.
3) Non-patent reference 2 reports that MK-801
and memantin as antagonists against NMDA receptor exert a
proliferation inhibition in the C6 and RG2 glioma
transplanted rat models.
However, it is criticized that the previous research
on glioma using such animal models are criticized since
they do not represent real growth of tumor (non-patent
Reference 3).
4) Additionally, non-patent reference 4 as one
critical review of the non-patent reference 1 suggests the
possibility of the inhibition AMPA receptors and NMDA
receptors as a multiple therapy for glioma. However, the
authors are suspicious about whether or not the animal
models using C6 and R62 glioma used in the non-patent
reference 1 can reflect human tumor.
Based on those described above, these previous
techniques do not include any specific descriptions about
the possibility that antagonists against AMPA receptor will
become a therapeutic agent of the most malignant human
glioblastoma among various types of glioma. The effect on
C6 and RG2 glioma does not suggest any possible therapeutic
effect on human glioblastoma.
Thus, the invention is not described in any these
previous techniques, and it cannot be derived readily from
them.
[Patent Reference 1]
PCT International Publication pamphlet WO 00/24395
[Non-patent Reference 1]
Proceedings of the National Academy of Sciences of
United States of America 98 (11), 6372-6377, 2001
[Non-patent Reference 2]
Nature Medicine 7(9), 1010-1015, 2001
[Non-patent Reference 3]
Nature Medicine 6(4), 369-370, 2000
[Non-patent Reference 4]
Nature Medicine 7(9), 994-995, 2001
Disclosure of the Invention
It is an objective of the invention to provide a
therapeutic agent for glioblastoma, which has a novel
action mechanism.
The inventors made investigations so as to attain
the object. The inventors found that the GluRl and/or
GluR4 subunit was expressed widely in glioblastoma cells,
particularly human primary glioblastoma cell and functioned
as a Ca2+-permeable AMPA receptor. Specifically, the
inventors found that the transformation of biological Ca2+-
permeable AMPA receptor into Ca2+-non-permeable AMPA
receptor by transfection of the GluR2(R) gene with
adenovirus vector inhibited migration and induced the
apoptosis of glioblastoma cells. In other words, the
inhibition of Ca2+ permeability by the presence of the
subunit GluR2(R) induces the cell death of glioblastoma
cells. Further, the inventors found that in contrast,
excess expression of Ca2+-permeable AMPA receptor promoted
not only the morphological change and growth of the tumor
cell but also the migration ability.
Still further, the inventor established an animal
model highly reflecting the pathological feature of human
glioblastoma and used this model for verifying the effect
in accordance with the invention. The animal model with a
transplanted human glioblastoma cell line CGNH-89 as
established by the inventor reflects the pathological
feature of human glioblastoma, where the cell vigorously
invades the inside of brain parenchyma and the subpial
brain to induce disseminated meningitis.
Accordingly, the inventors certified that a
compound, which has high antagonistic effect against AMPA
receptor inhibits tumor growth in an animal model
reflecting human glioblastoma, based on the findings that
the AMPA receptors of glioblastoma cell were composed of
the GluRl and/or 61uR4 subunit not GluR2 and the high Ca2+
permeability of the AMPA receptor was responsible for the
marked growth and migration abilities of human glioblastoma
cell. Thus, the invention has been achieved.
Therefore, the present invention relates to a
therapeutic agent for glioblastoma, which comprises a
compound having an activity of inhibiting an AMPA receptor
as the active ingredient.
Preferably, the present invention relates to a
therapeutic agent for glioblastoma, wherein the compound
having an activity of inhibiting an AMPA receptor is [7-
(lH-imidazol-1-yl)-6-nitro-2,3-dioxo-3,4-dihydroquinoxalin-
1(2H)-yl]acetic acid or a salt thereof or a hydrate
thereof.
Additionally, the present invention relates to a
therapeutic agent for glioblastoma, wherein the compound
having an activity of inhibiting an AMPA receptor is 2,3-
dihydroxy-6-nitro-7-sulfamoyl-benzo(F)-quinoxaline or a
salt thereof.
Still additionally, the present invention relates to
a therapeutic agent for glioblastoma, wherein the compound
having an activity of inhibiting an AMPA receptor is 2-[N-
(4-chlorophenyl)-N-methylamino]-4H-pyrido[3,2-e]-1,3-
thiazin-4-one or a salt thereof.
Additionally, the present invention relates to a
pharmaceutical composition for a therapeutic agent for
glioblastoma, which comprises a therapeutically effective
amount of a compound having an activity of inhibiting an
AMPA receptor and a pharmaceutically acceptable carrier;
the aforementioned pharmaceutical composition
wherein the compound having an activity of inhibiting an
AMPA receptor is preferably [7-(lH-imidazol-1-yl)-6-nitro-
2,3-dioxo-3,4-dihydroquinoxalin-l(2H)-yl]acetic acid or a
salt thereof or a hydrate thereof;
the aforementioned pharmaceutical composition
wherein the compound having an activity of inhibiting an
AMPA receptor is preferably 2,3-dihydroxy-6-nitro-7-
sulfamoyl-benzo(F)-quinoxaline or a salt thereof; and
the aforementioned pharmaceutical composition
wherein the compound having an activity of inhibiting an
AMPA receptor is preferably 2-[N-(4-chlorophenyl)-N-
methylamino]-4H-pyrido[3,2-e]-1,3-thiazin-4-one or a salt
thereof.
Still more, the present invention relates to the use
of a compound having an activity of inhibiting an AMPA
receptor for the manufacture of a medicament for treating
glioblastoma comprising a clinically effective amount of
the compound;
the aforementioned use thereof wherein the compound
having an activity of inhibiting an AMPA receptor is
preferably [7-(IH-imidazol-l-yl)-6-nitro-2,3-dioxo-3,4-
dihydroquinoxalin-1(2H)-yl]acetic acid or a salt thereof or
a hydrate thereof;
the aforementioned use thereof wherein the compound
having an activity of inhibiting an AMPA receptor is
preferably 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)-
quinoxaline or a salt thereof; and
the aforementioned use thereof wherein the compound
having an activity of inhibiting an AMPA receptor is
preferably 2-[N-(4-chlorophenyl)-N-methylamino]-4H-
pyrido[3,2-e]-1,3-thiazin-4-one or a salt thereof or a
hydrate thereof.
Furthermore, the present invention relates to a
method for treating glioblastoma comprising administering a
therapeutically effective amount of a compound having an
activity of inhibiting an AMPA receptor to a patient with
10
the disease; such method wherein the compound having an activity of inhibiting
an AMPA receptor is preferably [7- (lH-imidazol-l-yl)-6-nitro-2r 3-d»xo-3, 4-
dihydroquinoxalin-1 (2H)-yl] acetic acid or a salt thereof or a hydrate thereof;
the aforementioned method wherein the compound having an activity of
inhibiting an AMPA receptor is preferably 2,3-dihyclroxy-6-nitro-7-sulfamoyl-
benzo (F)-quinoxaline or a salt thereof; and
the aforementioned method wherein the compound having an activity of
inhibiting an AMPA receptor is preferably 2-{N-{4