Organic compounds -- part of the class 532-570 series – Organic compounds – Radioactive metal containing
Reexamination Certificate
2000-05-31
2002-10-22
Jones, Dameron L. (Department: 1619)
Organic compounds -- part of the class 532-570 series
Organic compounds
Radioactive metal containing
C424S001650, C424S009100, C424S001110, C549S034000, C549S089000
Reexamination Certificate
active
06469146
ABSTRACT:
TECHNICAL FIELD
The subject matter of the present invention is a radiopharmaceutical product using radioactive metal complexes for the selective labeling of lymphocytes.
Such radioactive products are suitable in particular for the diagnosis of inflammatory processes and of malignant lymphomas, and for radiotherapy of malignant lymphomas.
PRIOR ART
Radiolabeled products used for these diagnoses and therapies are described in particular in the work: Radiolabeled Blood Elements, published by J. Martin-Conin, Plenum Press, New-York, 1994, pages 261 to 263 [1] and pages 265 to 271 [2].
In these documents, lymphocytes labeled with
111
In-oxinetropolone, lymphocytes labeled with
99m
Tc-HMPAO, nanocolloids labeled with
99m
Tc-HSA, polyclonal human immunoglobulins or monoclonal antibodies are used.
These techniques do not give satisfactory results since it is necessary firstly to separate the lymphocytes from whole blood in order to label them with appropriate products.
More recently, it has been found that radiopharmaceutical products containing bis(dithiocarboxylato)-nitrurotechnetium-99m could be used to achieve selective labeling of leukocytes, and studies have been made on the influence of the hydrocarbon chain of the ligand on the results obtained, as described in Nuclear Medicine & Biology, 1997, volume 24, pages 439-445 [3] and 1999, volume 26, pages 225-231, [4]. Radiopharmaceutical products of this type are of great interest since when they placed in the presence of blood cells (erythrocytes, leukocytes, platelets) these radioactive complexes show selective affinity for leukocytes. Also, document [4] showed that the complex [
99m
TCN(CH
3
)(CH
2
)
8
CS
2
)
2
] also has selectivity for lymphocytes.
Contrary to radiolabeled granulocytes, which are routinely used in clinical practice to detect sites of infection and/or inflammation, radiolabeled lymphocytes have been little used either for diagnostic or for therapeutic purposes.
This is due to the combination of several technical or basic difficulties. Among operative difficulties, the need must be taken into account to make prior separation, before radiolabeling, of the lymphocytes from the other blood cells in whole blood, in particular from the granulocytes.
Despite the difficulties mentioned, radiolabeled lymphocytes could be used in man for improved diagnosis and for improved therapeutic management of diseases characterized by chronic inflammation.
Also, recently published results have shown that malignant lymphomas, in particular non-Hodgkin's lymphoma, could be successfully treated by radioimmunotherapy, a technique which consists of using a monoclonal antibody radiolabeled with &bgr;
−
ray emitters having a strong affinity for malignant lymphocytes. In this way the lymphocytes are radiated by the &bgr;
−
ray emission of the radioelement vectored by the antibody which binds itself to the surface of the cells. Radioimmunotherapy of lymphomas, however, encounters various difficulties, including the use of large quantities of non-labeled antibodies to saturate the high number of antigen sites present on the cells. The cost of treatment is therefore greatly increased. In addition, there is a risk that the injection of the first therapeutic dose may cause an immunity reaction which creates human antibodies directed against the antibodies used for treatment (anti-antibodies). If a second therapeutic dose is required in the same patient, it will be much less effective since the labeled antibody would be inhibited by the presence of anti-antibody antibodies. The use of a compound having a simple chemical structure which binds selectively to lymphocytes would avoid these types of problems.
The subject matter of the present invention is precisely radiopharmaceutical products using complexes having a simple chemical structure which do not give rise to the above-mentioned disadvantages.
DESCRIPTION OF THE DISCLOSURE
The subject matter of the present invention is a radiopharmaceutical product characterized in that it contains a radioactive metal complex meeting the formula:
[M(R
1
CS
2
)(R
1
CS
3
)
2
]
in which M is chosen from among
99m
Tc,
186
Re and
188
Re, and R
1
represents an alkyl, cycloalkyl, aralkyl or aryl group, which may or may not be substituted by one or more substituents chosen from among the halogen atoms, the hydroxyl group, the alkyl groups and the alcoxy groups.
In this radiopharmaceutical product, the radioactive metal M which may be
99m
Tc for diagnosis, or
186
Re or
188
Re for therapy, is coordinated by an assembly of non-homogeneous sulfured ligands, namely a dithiocarboxylate ligand (R
1
CS
2
)
−
and two trithioperoxycarboxylate ligands (R
1
CS
3
)
−
. In this structure, the radioactive metal is in M
3+
form.
The document: Inorganic Chemistry, 1997, vol. 36, pages 6144-6145 [5] describes a rhenium complex having the same type of structure but which is not obtained from
186
Re or
188
Re. It is therefore not a radiopharmaceutical product.
In the structure of the complexes of the invention, the R
1
groups of the sulfured ligands may be alkyl, cycloalkyl, aralkyl or aryl aliphatic groups. These groups may be non-substituted or substituted by one or more substituents chosen from among the halogen atoms, fluorine for example, the hydroxyl group, the alkyl groups and the alcoxy groups.
The alkyl groups used for R
1
may be linear or branched groups at C
1
to C
15
, preferably groups having 3 to 13 carbon atoms.
The cycloalkyl groups used for R
1
preferably have 3 to 7 carbon atoms, for example 6 carbon atoms.
The aryl groups used for R
1
may be of phenyl or naphthyl type.
The aralkyl groups used for R
1
may be of C
6
H
5
(CH
2
)
n
type in which n ranges from 1 to 3, preferably n equals 1 or 2.
Preferably, in accordance with the invention, the R
1
group is an aryl, aralkyl or cyclohexyl group that is optionally substituted.
Advantageously, when R
1
is an aryl group, it is chosen from among the phenyl groups, phenyl substituted by a methyl, ethyl, butyl, ethoxy, methoxy or hydroxyl group, phenyl substituted by a fluorine atom, phenyl substituted by three methyl groups, naphthyl and naphthyl substituted by a methyl group.
When R
1
is an aralkyl group, this is advantageously the benzyl or phenethyl group.
A further purpose of the invention is a method for preparing a radiopharmaceutical product containing a radioactive metal complex having the formula:
[M(R
1
CS
2
)(R
1
CS
3
)
2
]
in which M is chosen from among
99m
Tc,
186
Re and
188
Re, and R
1
represents an alkyl, cycloalkyl, aralkyl or aryl group, which may or may not be substituted by one or more substituents chosen from among the halogen atoms, the hydroxyl group, the alkyl groups and the alcoxy groups,
which consists of causing a salt of formula (MO
4
)
−
Z
1
+
, in which M is as defined above and Z
1
is a pharmaceutically acceptable cation, to react with a reducing agent, and of adding to the reaction mixture a dithiocarboxylate of formula (R
1
CS
2
)
−
Z
2
+
in which R
1
is as defined above and Z
2
+
represents a pharmaceutically acceptable cation.
The pharmaceutically acceptable cations used for Z
1
may be ions of alkali or alkaline earth metals, for example Na.
The pharmaceutically acceptable cations used for Z
2
may be chosen from among MgX
+
in which X is a halogen atom such as Br or Cl, the quaternary ammonium cations, and the ions of alkaline earth metals such as Na.
The quaternary ammonium cations may for example be of NR
4
type, in which R is an alkyl group, methyl for example. It is also possible to use quaternary ammonium cations of piperidinium type having the formula C
5
H
10
ONH
2
+
.
In the method of the invention, the reducing agent used may be of various types. In particular a reducing agent may be used which is made up of a tin salt associated with a complexing agent having complexing properties for tin that are greater than those of dithiocarboxylate
Bellande Emmanuel
Mevellec Franck
Noiret Nicolas
Pasqualini Roberto
Patin Henri
Cis Bio International
Jones Dameron L.
LandOfFree
Radiopharmaceutical products suitable for the selective... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radiopharmaceutical products suitable for the selective..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiopharmaceutical products suitable for the selective... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2969595