GB2262528A - Tumour-binding protein comprising a phosphokinase peptide substrate - Google Patents

Tumour-binding protein comprising a phosphokinase peptide substrate Download PDF

Info

Publication number
GB2262528A
GB2262528A GB9226144A GB9226144A GB2262528A GB 2262528 A GB2262528 A GB 2262528A GB 9226144 A GB9226144 A GB 9226144A GB 9226144 A GB9226144 A GB 9226144A GB 2262528 A GB2262528 A GB 2262528A
Authority
GB
United Kingdom
Prior art keywords
structurally
nhr
peptide
grouping
residue
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9226144A
Other versions
GB2262528B (en
GB9226144D0 (en
Inventor
Andrew Malcolm Creighton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BTG International Ltd
Original Assignee
British Technology Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Technology Group Ltd filed Critical British Technology Group Ltd
Publication of GB9226144D0 publication Critical patent/GB9226144D0/en
Publication of GB2262528A publication Critical patent/GB2262528A/en
Application granted granted Critical
Publication of GB2262528B publication Critical patent/GB2262528B/en
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K17/00—Carrier-bound or immobilised peptides; Preparation thereof
    • C07K17/02—Peptides being immobilised on, or in, an organic carrier
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/62—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being a protein, peptide or polyamino acid
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
    • A61K47/6801—Drug-antibody or immunoglobulin conjugates defined by the pharmacologically or therapeutically active agent
    • A61K47/6803—Drugs conjugated to an antibody or immunoglobulin, e.g. cisplatin-antibody conjugates
    • A61K47/6811—Drugs conjugated to an antibody or immunoglobulin, e.g. cisplatin-antibody conjugates the drug being a protein or peptide, e.g. transferrin or bleomycin
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K1/00—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length
    • C07K1/107—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length by chemical modification of precursor peptides
    • C07K1/1072—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length by chemical modification of precursor peptides by covalent attachment of residues or functional groups
    • C07K1/1075—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length by chemical modification of precursor peptides by covalent attachment of residues or functional groups by covalent attachment of amino acids or peptide residues
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K2121/00—Preparations for use in therapy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/55—Design of synthesis routes, e.g. reducing the use of auxiliary or protecting groups

Abstract

A structurally modified protein is provided that will bind to a tumour-associated structure wherein the amino group in at least one basic amino acid in the binding protein is structurally modified to convert the amino group, -NH2, to the grouping NH-CO-X-NHR in which R is H or an amino protecting group and the grouping -CO-X-NHR is the residue of a peptide of the formula NHR-X-COOH capable of acting as a substrate for a phosphokinase. The modified protein may be radiolabelled.

Description

wtE IMPROVEMENTS RELATING 10 T1E RADIOLABELLING OF PROTEINS This invention relates to improvements in the labelling of monoclonal antibodies and other proteins with 32p. The term "protein" as used herein includes polypeptides.
Radiation therapy, particularly using 32p, is of interest as a possible method of treatment of certain cancer conditions and it is therefore of interest to be able to label antibodies or other targeting molecules with 32p. However1 the labelling of the antibody or similar targeting molecule must be done in such a way that the specificity of the antibody or similar targeting molecule is retained in a labelled molecule that has appropriate in vivo stability.
Our earlier Patent, GB-B-21l861579, describes a system for modifying a protein that will bind ith a tumour-associated structure comprising the introduction into the binding protein of a peptide region which is capable of acting as a substrate for a phosphokinase. The resulting modified binding protein can then be 32p labelled by reacting it with a 32P labelled gamma nucleotide triphosphate in the presence of a phosphokinase.
In accordance with the procedures described in our earlier Patent GB-B- 2,186,579 the peptide region capable of acting as a substrate for a phosphokinase is introduced into the binding protein by using a hetero-bifunctional protein crosslinking agent.
For example, the targeting molecule may be reacted with N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP) followed by reduction with dithiothreitol. The reaction with SPDP introduces the dithiopropionyl group onto a side-chain amino group of a lysine residue in the targeting molecule while the subsequent reduction step converts the dithio grouping into a terminal thiol group.
This terminal thiol group provides the reactive site for introduction of the substrate molecule.
In accordance with the procedure described in our earlier UK Patent1 it is then necessary to activate the substrate molecule by reacting the N-terminus of the substrate molecule with a bridging molecule which in turn can be reacted with the terminal thiol group on the targeting molecule. For example, if the substrate molecule has an N-terminal leucine residue, its amino group can be reacted with an N-hydroxy-succinimidyl ester to give for example an iodoacetamide or a phenyl maleimide which can then react with the thiol group of the thiopropionamido residue introduced on the targeting molecule so that the substrate molecule becomes attached to the targeting molecule through a short bridging group including a thio link.If the substrate molecule has an N-terminal cysteine residue, then its thiol group can be reacted with succinimidyl-4-(p-maleimidophenyl)butyrate and the reaction product then reacted with the targeting molecule.
In the targeting molecule/substrate conjugates described in our earlier Patent, the substrate molecule is linked through its N-terminus by a short sulphur-containing bridge to the terminal amino group of the lysine residues of the targeting molecule.
However, the procedure to bring about this conjugation is chemically complex involving the use of the hetero-bifunctional bridging molecules.
We have now found that it is possible to introduce a targeting molecule/substrate conjugate by much simpler synthetic methods involving conventional peptide chemistry to give a phosphorylatable conjugate in which the substrate molecule is directly bonded through its carboxy terminus through a peptide link to the targeting molecule and that the resulting targeting molecule/substrate conjugates hereinafter referred to as structurally-modified targeting proteins, structurally-modified proteins or targeting protein/substrate peptide conjugates, when labelled with 32p, give conjugates that are more effective in vivo as therapeutic reagents.
Accordingly, the present invention provides a structurallymodified protein that will bind to a tumour-associated structure wherein the amino group in at least one basic amino acid in the binding protein is structurally modified to convert the amino group -NH2 to the grouping -NH-CO-X-NHR in which R is H or an amino protecting group and the grouping -CO-X-NHR is the residue of a peptide of the formula NllR-X-COOIS capable of acting as a substrate for a phosphokinase.
In accordance with the present invention, the structurally modified proteins are prepared by conventional peptide synthesis wherein the terminal carboxy group of the substrate peptide is linked to the amino group on a basic amino acid, normally lysine, contained within the sequence of the targeting molecule to form an amide linkage. Such amide linkages can be formed, for example, by protecting the amino group at the N-terminus of the substrate peptide by an amino protecting group, activating the free carboxy group at the carboxy terminus of the substrate peptide and reacting the activated substrate peptide with the targeting molecule so that an amide bond is formed between the activated carboxy group of the substrate peptide and the amino group in the basic amino acid in the targeting protein.
In accordance with the present invention the substrate peptide becomes linked by its carboxy terminus through an amide bond to the amino terminus of one or more of the basic amino acid units in the targeting protein. Such basic amino acids will normally be lysine where the epsilon amino group is available for amide formation.
The number of basic amino acids in the targeting molecule that will be linked to a substrate peptide will depend upon the degree of phosphorylation ultimately required in the therapeutic reagent.
Where the targeting protein is rich in lysine residues, it is less important that all of the lysine residues react than it is for a targeting protein that is relatively poor in lysine residues but the relative proportion of reactants will normally be such that sufficient of the lysine residues in the targeting protein are reacted with the substrate peptide and that sufficient of the substrate peptide conjugated into the targeting protein are phosphorylated to give a 32P conjugate that will have a therapeutically effective effect available from an amount of 32P conjugate that can be conveniently administered.
One of the attractions of the present invention is the relative simplicity with which the substrate peptide can be built into the targeting protein, compared to the chemistry involved in the method described in our earlier Patent. For example, all that is necessary, in accordance with the present invention, is for the N-terminus of the substrate peptide to be protected, and this can conveniently be done earlier by acetylation during synthesis of the substrate peptides.The carboxy terminus of the substrate peptide is then activated for amide formation e.g. by reaction with N-hydroxysuccinimide to form the N-hydroxysuccinimide ester of the N-protected substrate peptide in the presence of a dehydrating agent such as those used in peptide bond formation, for example di-imides such as di-isopropyl carbo-diimide, and the solution containing the reaction product can then be reacted, without the need for isolation or purification directly with the targeting protein to form the amide bond between the targeting protein and the substrate peptide.
This amide bond formation can conveniently occur by bringing the reagents together in a borate buffer solution normally at a pH of at least 8, e.g. pH 8-10, preferably pH 9. The majority of the amide bond formation between the substrate peptide and targeting protein occurs within an hour or two but it is experimentally convenient to leave the reagents at ambient temperature, e.g. 15 to 20oC for 8 to 24 hours to maximise amide bond formation.
A further attraction of the present simple synthesis is the possibility of preparing a stock of the activated ester of the N-protected substrate peptide which can be stored stably in the original reaction solution at below -lOoC, e.g. at 18or, for prolonged periods and simply brought back to room temperature when it is required for reaction with the targeting protein.
The targeting protein used in the present invention can be any one of those described in our earlier-mentioned British Patent.
These will normally be monoclonal antibodies that will bind with a tumour-associated antigen, for example antigens associated with solid tumours with relatively poor blood supplies. Such solid tumours include those found in the colon, ovaries and lungs and monoclonal antibodies to such tumour-associated antigens are already known and have already been used as delivery vehicles for other anti-tumour agents.
More generally, the binding protein may be any protein that will bind with a tumour-associated protein or other tumour-associated structure such as a glycolipid or carbohydrate, where the tumour is one susceptible to high energy beta particles and, in addition to monoclonal antibodies, the targeting protein could be, for example, an Fab fragment of an antibody or a hormone or similar peptide that will bind to an appropriate receptor site identified on certain types of tumour cell, e.g.
melanocyte-stimulating hormone, epithelial growth factor, interferons and mitogenic peptides such as bombesin.
For the purposes of an experimental demonstration of the benefits of the present invention, work is done with monoclonal antibodies usable in rat and mouse experimental systems.
7he substrate peptides that can be used in the present invention are essentially the same as those used in the invention described in our above-mentioned British Patent. In the phosphorylation step, commercial availability of phosphokinases favours the use of serine or threonine kinases which in turn points to the use of substrate peptides containing serine and/or threonine residues. In general, serine-containing substrates phosphorylate relatively easily while threonine-containing substrates lead to products with relatively higher in vivo stability to phosphatases.
Preferably then, the substrate peptide contains a threonine and/or serine residue and more preferably contains a threonine residue.
Examples of such substrate peptides include the heptapeptide that has become known as Kemptide having the structure Leu.Arg.Arg.Ala.Ser.Leu.Gly or related peptides of the structure Leu.Arg.Arg.Ala.Thr. Leu.Gly Arg.Arg.Arg.Arg. Pro.Ser. Pro.Ala Arg.Arg.Arg.Arg.Pro.Thr.Pro.Ala Leu.Arg.Arg.Ala.Ser.Leu.Gly.Ala Leu.Arg.Arg.Ala.Thr.Leu.Gly.Ala Lys.Tyr.Arg.Arg.Ala.Ser.Leu.Gly Cys.Arg.Arg.Lys.Ala.Ser.Gly.Pro.Pro.Val Leu.Arg.Arg.Ser.Leu.Gly.Ala Leu.Arg.Arg.Ser. Leu.Gly Leu.Arg.Arg.Thr.Leu.Gly Arg.Arg.Arg.Arg.Pro.Thr.Pro.Ala.Ala Arg.Arg.Arg.Arg.Pro.Thr.Val.Ala In the above peptides and all other peptides listed or referred to in this specification, the peptides read from left to right in the N-terminal to C-terminal direction.
It is necessary to protect the N-terminus of the substrate peptide during the reaction with the targeting protein. Protection by acetylation is the preferred method of protection since such acetyl groups are clinically acceptable and inert and it is not necessary to remove this protecting group either during the subsequent phosphorylation step or during the clinical use of the phosphorylated material. It is also introduced very conveniently during solid phase peptide synthesis after detachment of the protected peptide from the Merrifield resin and before removal of the other protecting groups. Since the terminal acetylamino group is so similar to a peptide bond, it is quite stable to the standard "deprotecting" procedures.
Once the substrate peptide has been introduced into the targeting protein, it can be phosphorylated or thiophosphorylated to introduce 32P. The phosphorylation can be carried out by procedures known per se and by procedures which are described in our earlier-mentioned British Patent. The phosphorylation is normally carried out by using gamma-32P-adenosine triphosphate (gamma-32P-ATP); or using gamma-32P guanidine triphosphate, in the presence of a serine or threonine phosphokinase, e.g. a bovine heart protein kinase, which brings about the labelling with 32P of the serine or threonine residue in the substrate peptide.Although the serine-containing peptides can normally be phosphorylated very rapidly at 370C, or more conveniently at room temperature, the threonine containing peptides usually require a longer time and it is necessary to reduce the temperature of the incubation to maintain the stability of the enzyme. Conveniently these labellings are carried out at 100C overnight although these conditions are not optimal. Alternatively, one of the commercially available tyrosine phosphokinases can be used in the presence of gamma-32P-ATP to introduce 32P onto the tyrosine residue of the substrate peptide.
The phosphorylation of the substrate peptide portion of the structurally modified protein of the invention is normally carried out shortly prior to the clinical use of the labelled conjugate but the labelled conjugates are reasonably stable and can be stored prior to their clinical use.
Another synthetic alternative is to label the substrate peptide with 32p by treatment with, for example, gamma-32P-ATP in the presence of the appropriate phosphokinase and then to bring about the conjugation of the labelled substrate peptide with the targeting protein by the methods described above. In this modification, attention must be paid to the possibility of reaction occurring between the activated substrate peptide and any basic amino groups that may be present in the phosphokinase.
As an alternative to phosphorylation, the structurally-modified targeting proteins of the invention can be thiophosphorylated by methods known per se, e.g. those disclosed in our W090/11289.
The 32p labelled structurally-modified targeting proteins including the N-acetyl conjugates, are novel compounds, as are the unlabelled proteins and both the labelled and unlabelled proteins form part of the present invention.
Although unlabelled proteins of the present invention are designed primarily for 32P labelling by enzymatic methods, the conjugates are also available for 32P labelling by conventional chemical means.
Once the phosphorylation of the structurally-modified targeting proteins has been completed, the 32P labelled conjugate can be purified by standard chromatographic techniques such as gel filtration, e.g. on a SephadexR column equilibrated with phosphate buffered saline. The 32P conjugate solution obtained in this way may then be filtered, e.g. using a 0.22 vm pore size filter so that it is in a suitable form for clinical use.
A further feature of the present invention provides a pharmaceutical composition, particularly one for parenteral administration, comprising a pharmaceutically acceptable diluent or carrier and the 32P-labelled structurally-modified targeting protein of the present invention.
Once a trace dose of the protein of the present invention is shown to target preferentially to a tumour region as compared to normal tissue, the labelled protein may then be administered intravenously or into various body regions for example by intraperitoneal, intrapleural or intra-arterial infusion.
The benefit of radiation treatment with 32P for certain types of cancer is already-well established. The advantage of presenting the 32p source in one of the labelled proteins of the present invention is that it is possible to bring about a higher concentration of the labelled conjugate in the region of the tumour than appears to be possible by the use of the labelled conjugates of the type described in our earlier-mentioned British Patent and indeed, we have found that in certain instances, it is possible to make available 20% or more of the 32P-labelled material in the target area than is possible by the use of the 32P-labelled conjugates of the type described in our earlier-mentioned British Patent.
The following Examples are given to illustrate the present invention. Results of the experiments described in Example 4 are illustrated in Figures 1 and 2 of the accompanying Drawings, and the Results of experiments described in Example 6 are shown in Figure 3.
EXAMPLE I Preparation of Pl-peptide (CH3 CO-NH-Leu.Arg.Arg.Ser.Leu.Gly.Ala) This was prepared by conventional solid-phase peptide synthesis on an ' Applied Biosystems 430A Peptide Synthesiser", the terminal acetyl group being added by treating the peptide with acetic anhydride after detachment from the resin but before cleaving the other protecting groups. The product showed essentially a single peak by HPLC analysis and the calculated molecular weight of 885 was confirmed by mass spectra.
Similarly prepared were: CH3CO-NH-Leu.Arg.Arg.Ser.Leu.Gly - Peptide 2 CH3CO-NIS-Leu.Arg.Arg.Thr.Leu.Gly - Peptide 3 CH3CO-NH-Arg.Arg.Arg.Arg.Pro.Thr.Pro.Ala.Ala - Peptide 4 and ClS3CO-N11-Arg.Arg.Arg.Arg.Pro.Thr.Pro.Val.Ala - Peptide 5 EXAMPLE 2 Coupling of Pi-peptide to the monoclonal antibody, SM3 to give SM3/P1 conjugate The activated ester of the Pl-peptide was prepared by adding a solution of N-hydroxysuccinimide 50 pl (5.65 poles) of a stock solution of 13.0 mg/ml in dry dimethylformamide (DMF)3, followed by a solution of diisopropyl carbodiimide E50 pl (5.65 'moles) of a stock solution of 17.4 pl/ml in dry DMF] to a solution of Pl-peptide (5 mg, 5.65 poles) in dry DMF (250 pal). The reaction mixture was allowed to stand at about 200C overnight (ca. 18 hours) and then either used directly for conjugating to the antibody as described below or stored under anhydrous conditions at -180C for use later.
The solution of the activated ester of the peptide, prepared as above (20 pal), was added to 820 iil of a solution containing a monoclonal antibody SM3 (5.0 mg) that will target ovarian tumour tissue in borate buffer (0.05 M sodium borate containing 0.1 M sodium chloride and 0.5% v/v butan-l-ol; pH 9.0). A hybridoma producing SM3 was deposited in the European Collection of Animal Cell Cultures at Porton Down, Wiltshire, England, on 7th January 1987 as Deposit No. ECACC-87010701.After incubation at about 200C for one hour, the reaction mixture was fractionated using a Pharmacia FPLC system. The sample was applied to a Superose 6 column, pre-equilibrated in the "enzyme buffer" [50 mM dipotassium hydrogen phosphate (plus 7.0) containing 5 mM magnesium chloride and 0.25 mM EGTA (ethyleneglycol-bis-ss-amino- ethyl-ether)-N,N,N'N'-tetraacetic acid)], and the protein, eluting as a single peak of molecular weight about 150,000 (about 4.5 mg (i.e. at least 90% yield) in 5 ml buffer) was filtered (0.22 vm) and stored at 40C. The average number of Pl-peptide groups conjugated to each antibody molecule by this procedure was known to be about 1.5 by trace-labelling a sample of the product with 32p.
SM3-P2, SM3-P3 and SM3-P5 conjugates were prepared in a similar manner from peptide 2, peptide 3 and peptide 5 respectively.
EXAMPLE 3 Phosphorylation of SM3-P1 conjugate For high specific activity labelling, SM3-P1 stock solution (137 pl at 0.73 mg/ml, prepared as described in Example 2) and x 5 "enzyme buffer" (7 1, 250 mM dipotassium hydrogen phosphate (plA 7.0) containing 25 mM magnesium chloride and 1.25 mM EGTA) was added to 1 mCi gamma of 32P-ATP (adenosine triphosphate) (20 pl, PB10218, Amersham International), followed by bovine heart protein kinase (10 v1, 50 U, Sigma). The reaction was incubated for 30 minutes at 370C and the protein was then desalted using a G50 'Sephadex' column (10 ml) equilibrated in phosphate-buffered saline which had been prewashed in phosphate-buffered saline containing bovine serum albumin (2 mg/ml).Under these conditions, about 0.03 phosphate moieties were incorporated into each molecule of SM3 with a specific activity of about 1.25 pCi/pg (42% yield).
This labelled conjugate was designated SM3-32P-P1. SM3-32P-P2 was prepared in a similar manner giving a product of specific activity 1.37 vCi/ug (46% yield). For comparison purposes SM3 was coupled with Kemptide using SPDP using the procedure described in our above-mentioned British Patent and the conjugate labelled with 32P as described above to give SM3-32P-KT having a specific activity of about 1.25 pCiSpg.
EXAMPLE 4 Rate of clearance of 32P-phosphorylated-SM3 from the blood Balb/c mice (6-7/group) were injected (i.v.) with 5-10 iig of either SM3-32P-P1 or SM3-32P-KT. Blood samples were taken via the tail vein at various time points, the plasma separated and the acid-precipitable radioactivity counted. The rate of clearance of the radioactivity was demonstrably slower for the Pl-peptide as indicated in Figure la. If the same data is replotted on a linear scale and the radioactivity adjusted to allow for the decay due to the 14-day half-life, the persistence of 32P-activity in the blood can be shown to be 41% greater (AUC or area under the curve) with the Pl-peptide than with the sulphide-linked KT peptide (Fig. lb).
Similar results were obtained with SM3 conjugates when administered by the intraperitoneal route and the results are illustrated in Figures 2a and 2b.
EXAMPLE 5 Phosphorylation of SM3-P3 and SM3-P5 conjugates The phosphorylation of the SM3-P3 and SM3-P5 conjugates was carried out in a similar manner to Example 3 except that the incubation conditions were 24 hours at 100C and 26 hours at lOoC respectively. Thestconditions, which were not optimal, gave SM3-32P-P3 at 0.4 pCi/pg (19% yield) and SM3-32P-P5 at 0.65 pCi/pg (18% yield).
EXAMPLE 6 Rate of clearance of SM3-32P-Pl and SM3-32P-P3 from the blood and accumulation of 32P in bone/bone marrow Balb/c mice (groups of four) were injected (i.v.) with 5-10 pg each of either SM3-32P-P1 or SM3-32P-P3. At 1, 2, 4, 8 and 12 day intervals, the mice were killed using C02 and 1-2 ml of blood was removed, the plasma separated and the acid-precipitable radioactivity counted. The rate of clearance of the radioactivity was demonstrably slower for the P3-conjugate (Figure 3a).
Individual femurs were carefully removed, cleaned thoroughly externally while retaining the marrow, weighed, digested in methanolic SOLI, and the radioactivity counted following neutralisation. The results showed relatively lower levels of the radioactivity from the P3, threonine-based, conjugate (Figure 3b).
The blood clearance and accumulation of 32P in the bone/bone marrow data together confirm the greater stability in vivo of the threonine-based conjugate.

Claims (13)

1. A structurally-modified protein that will bind to a tumour-associated structure wherein the amino group in at least one basic amino acid in the binding protein is structurally modified to convert the amino group, -NH2, to the grouping -NH-CO-X-NHR in which R is H or an amino protecting group and the grouping -CO-X-NI1R is the residue of a peptide of the formula NHR-X-COOH capable of acting as a substrate for a phosphokinase.
2. A structurally-modified protein according to Claim 1 wherein at least one of the basic amino acids in the binding protein is lysine.
3. A structurally-modified protein according to Claim 1 or 2 wherein the grouping -CO-X-NHR contains a serine and/or threonine residue.
4. A structurally-modified protein according to Claim 3 wherein the grouping -CO-X-NHR contains a threonine residue.
5. A structurally-modified protein according to any of Claims 1 to 4 wherein the grouping -CO-X-NHR is the residue of the peptide Leu Arg Arg Ala Ser Leu Gly or an amino protected derivative thereof.
6. A structurally-modified protein according to any of Claims 1 to 4 wherein the grouping -CO-X-NHR is the residue of the peptide Leu Arg Arg Ala Thr Leu Gly or an amino protected derivative thereof.
7. A structurally-modified protein according to any of Claims 1 to 4 wherein the grouping -CO-X-NHR is the residue of the peptide Leu Arg Arg Ser Leu Gly Ala or an amino protected derivative thereof.
8. A structurally-modified protein according to any of Claims 1 to 4 wherein the grouping -CO-X-NHR is the residue of the peptide Leu Arg Arg Ser Leu or an amino protected derivative thereof.
9. A structurally-modified protein according to any of Claims 1 to 4 wherein the grouping -CO-X-NHR is the residue of the peptide Leu Arg Arg Thr Leu Gly or an amino protected derivative thereof.
10. A structurally-modified protein according to any of Claims 1 to 4 wherein the grouping -CO-X-NHR is the residue of the peptide Arg Arg Arg Arg Pro Thr Pro Val Ala or an amino protected derivative thereof.
11. A structurally-modified protein according to any preceding claim wherein R is an acetyl group.
12. A structurally-modified protein according to any preceding claim which is phosphorylated or thiophosphorylated to introduce 32P.
13. A pharmaceutical composition comprising a stucturally modified protein according to Claim 1 and a pharmaceutically acceptable diluent or carrier.
l± A pharmaceutical composition according to Claim 13 adapted for parenteral administration.
1g. A method for structurally modifying a protein that will bind to a tumour-associated structure which comprises structurally modifying the amino group in at least one basic amino acid in the binding protein to convert the amino group, -NH2, to the grouping -NH-CO-X-NHR in which R is H or an amino protecting group and the grouping -CO-X-NHR is the residue of a peptide of the formula NHR-X-COOH capable of acting as a substrate for phosphokinase.
GB9226144A 1991-12-16 1992-12-15 Further improvements relating to the radiolabelling of proteins Revoked GB2262528B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB919126650A GB9126650D0 (en) 1991-12-16 1991-12-16 Further improvements relating to the radiolabelling of proteins

Publications (3)

Publication Number Publication Date
GB9226144D0 GB9226144D0 (en) 1993-02-10
GB2262528A true GB2262528A (en) 1993-06-23
GB2262528B GB2262528B (en) 1995-08-16

Family

ID=10706322

Family Applications (2)

Application Number Title Priority Date Filing Date
GB919126650A Pending GB9126650D0 (en) 1991-12-16 1991-12-16 Further improvements relating to the radiolabelling of proteins
GB9226144A Revoked GB2262528B (en) 1991-12-16 1992-12-15 Further improvements relating to the radiolabelling of proteins

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB919126650A Pending GB9126650D0 (en) 1991-12-16 1991-12-16 Further improvements relating to the radiolabelling of proteins

Country Status (8)

Country Link
US (1) US5762906A (en)
EP (1) EP0618816B1 (en)
JP (1) JPH07502502A (en)
AT (1) ATE180679T1 (en)
CA (1) CA2125975A1 (en)
DE (1) DE69229356T2 (en)
GB (2) GB9126650D0 (en)
WO (1) WO1993011796A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996023816A1 (en) * 1995-02-01 1996-08-08 British Technology Group Limited Radiolabelled proteins
EP0787138A1 (en) * 1994-10-05 1997-08-06 Immunomedics, Inc. Radioactive phosphorous labeling of proteins for targeted radiotherapy

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL115177A0 (en) * 1994-09-16 1995-12-31 Immunomedics Inc Phosphorus-32 labeling of antibodies for cancer therapy
US6605031B1 (en) 1999-09-22 2003-08-12 Advanced Cardiovascular Systems, Inc. Stepped centering balloon for optimal radiation delivery
US6582417B1 (en) 1999-09-22 2003-06-24 Advanced Cardiovascular Systems, Inc. Methods and apparatuses for radiation treatment
US7163504B1 (en) 2000-02-16 2007-01-16 Advanced Cardiovascular Systems, Inc. Multi-lumen fluted balloon radiation centering catheter
US7994449B2 (en) 2000-02-16 2011-08-09 Advanced Cardiovascular Systems, Inc. Square-wave laser bonding

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2186579A (en) * 1986-01-21 1987-08-19 Brian Maurice John Foxwell Improvements relating to the radio-labelling of proteins
GB2228262A (en) * 1989-01-25 1990-08-22 Nat Inst Immunology Antigenic derivative of GnRH

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1338860C (en) * 1987-04-13 1997-01-21 Peter Parker Radiolabelling of proteins
GB8906708D0 (en) * 1989-03-23 1989-05-10 Foxwell Brian M J Improvements relating to the radiolabelling of proteins
GB8916806D0 (en) * 1989-07-22 1989-09-06 Univ Wales Medicine Modified proteins

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2186579A (en) * 1986-01-21 1987-08-19 Brian Maurice John Foxwell Improvements relating to the radio-labelling of proteins
GB2228262A (en) * 1989-01-25 1990-08-22 Nat Inst Immunology Antigenic derivative of GnRH

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Proc. Soc. Exp. Biol. Med. 1978, 158, 643-646 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0787138A1 (en) * 1994-10-05 1997-08-06 Immunomedics, Inc. Radioactive phosphorous labeling of proteins for targeted radiotherapy
US5728369A (en) * 1994-10-05 1998-03-17 Immunomedics, Inc. Radioactive phosphorus labeling of proteins for targeted radiotherapy
US5976492A (en) * 1994-10-05 1999-11-02 Immunomedics, Inc. Radioactive phosphorus labeled proteins for targeted radiotherapy
EP0787138A4 (en) * 1994-10-05 2000-03-08 Immunomedics Inc Radioactive phosphorous labeling of proteins for targeted radiotherapy
WO1996023816A1 (en) * 1995-02-01 1996-08-08 British Technology Group Limited Radiolabelled proteins

Also Published As

Publication number Publication date
WO1993011796A1 (en) 1993-06-24
GB9126650D0 (en) 1992-02-12
JPH07502502A (en) 1995-03-16
GB2262528B (en) 1995-08-16
ATE180679T1 (en) 1999-06-15
US5762906A (en) 1998-06-09
CA2125975A1 (en) 1993-06-24
EP0618816B1 (en) 1999-06-02
GB9226144D0 (en) 1993-02-10
EP0618816A1 (en) 1994-10-12
DE69229356T2 (en) 1999-11-04
DE69229356D1 (en) 1999-07-08

Similar Documents

Publication Publication Date Title
JP7417432B2 (en) New linker, its production method and its application
US5459240A (en) Peptides which serve as substrates for a phosphokinase and methods for their use to modify antibodies in order to facilitate radioabelling of antibodies with 32 P
US11911434B2 (en) Stable antibody-drug conjugate, preparation method therefor, and use thereof
EP0429626B2 (en) Synthetic peptides for use in vivo in thrombus detection
KR100361075B1 (en) Receptor Modulators and Associated Methods
US5840880A (en) Receptor modulating agents
US5869465A (en) Methods of receptor modulation and uses therefor
US5922859A (en) Complexes containing nucleic acid which can be taken-up by endocytosis into higher eukaryotic cells
US5976492A (en) Radioactive phosphorus labeled proteins for targeted radiotherapy
EP0618816B1 (en) Further improvements relating to the radiolabelling of proteins
US5739287A (en) Biotinylated cobalamins
CN114630928A (en) Half-life-prolonged drug, library thereof, preparation method and application
JP2942776B2 (en) Improvements on radiolabeling of proteins
GB2186579A (en) Improvements relating to the radio-labelling of proteins
US5670628A (en) Radio-labelling of proteins
CA2155953A1 (en) Protein conjugates, compositions containing them and their applications as medicament
JP2002513776A (en) Positron emission tomography using gallium-68 chelate

Legal Events

Date Code Title Description
773K Patent revoked under sect. 73(2)/1977