Classifications

• • 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
  • A61K47/64—Drug-peptide, drug-protein or drug-polyamino acid conjugates, i.e. the modifying agent being a peptide, protein or polyamino acid which is covalently bonded or complexed to a therapeutically active agent
  • A61K47/642—Drug-peptide, drug-protein or drug-polyamino acid conjugates, i.e. the modifying agent being a peptide, protein or polyamino acid which is covalently bonded or complexed to a therapeutically active agent the peptide or protein in the drug conjugate being a cytokine, e.g. IL2, chemokine, growth factors or interferons being the inactive part of the conjugate

Definitions

• the present invention relates to targeted toxin molecules comprising a toxin and a (proteinaceous) molecule with binding activity for a receptor on the surface of a target cell.
• the targeted toxin molecules are directed to a receptor which is specific for a certain group of cells, these cells can be specifically eliminated.
• Such targeted toxin molecules are useful in tu ortherapy whereby the receptor on the cell surface is specific for tumor cells or at least is preferentially expressed by said tumorcells.
• the targeted toxin molecules can also be used in preventing allograft rejection and/or autoimmune diseases. In both the latter cases the aim is to suppress the cells (lymphocytes) which are responsible for the allograft rejection or the autoimmune response.
• a second disadvantage of methods using antisera is that the antisera usually are of animal origin. Eventually they will evoke an immunoresponse by the patient which will limit the use of such antisera to a very restricted number of administrations.
• An elegant approach to selectively suppress or eliminate a certain subset of cells is to direct a conjugate of a toxin, or possibly a radionuclide, and a (usually) proteinaceous substance with binding specificity for the receptors on the surface of said subset of cells to that subset, making use of the binding of said proteinaceous substance to the cellsurface.
• One method employs a (monoclonal) antibody or a fragment thereof, which is directed to the receptor.
• the expression ligand is intended to also include fragments,derivatives or mimicking agents of either proteinaceous or other nature.
• T-cells of a patient with an unwanted immunoresponse A subset of cells of particular interest for the above-mentioned methods of suppression or elimination is the set of activated T-cells of a patient with an unwanted immunoresponse. It is well known that during the activation processes leading to an (auto-) immunereaction, T- cells express high numbers of Interleukin-2 receptors. These receptors bind Interleukin-2 (IL-2) that may also be produced by these cells (Autocrine stimulation) . Consequently, the cells start to proliferate.
• IL-2 Interleukin-2
• the Pseudomonas exotoxin is a toxin with a high molecular weight which will, as antibodies and/or antigens of foreign origin do, elicit an immunoresponse in the patient.
• the present invention provides a toxin which will not evoke such an immuneresponse.
• the present invention provides a targeted toxin molecule comprising the ligand or a functional fragment or a derivative of one of both, for a receptor on the cell surface of a target cell and a toxin with a molecular weight of no more than 1500 D.
• the targeted toxin molecules of the invention are particularly suitable as therapeutics for autoimmune diseases in general and for rheumatoid arthritis in particular.
• targeted toxin molecules may be used to remove IL-2 expressing haematopoietic cell leukemias, to induce specific tolerance in transplantation patients or in patients receiving treatment with an antibody of foreign origin.
• fragments of the ligand specific for the chosen receptor may be used.
• fragments preferably should comprise (an amino acid sequence of) the receptor binding domains of the ligand or a functional derivative thereof.
• the receptor binding domains appear to lie within the fragments comprising the 33- 56 and the 11-20 amino acid sequences of IL-2.
• the first fragment appears to bind the p55 chain of the IL-2 receptor, whereas the second fragment appears to bind the p75 chain.
• An additional advantage of these fragments is that they may be produced synthetically without time consuming genetic engineering and/or purification.
• a pretargeting scheme actually creates an "address" site (receptor) on the target molecule, which can be recognized by a conjugate according to the invention.
• Pretargeting schemes have the advantage that there is no toxic compound present during localization of the first targeting moiety so that the damage to non target tissues can be reduced, especially when the specificity of the first targeting moiety is not too high.
• lymphokine receptors for instance lymphokine receptors, all T-cell receptors, Acetyl Cholin receptors, Epidermal Growth Factor receptors, Luteinizing Hormone receptors, Tumor Necrosis Factor a receptors, Transforming Growth Factor ⁇ receptors, reproductive hormone recptors (such as the hCG receptor) and so on.
• Suitable toxins will usually have a molecular weight of less than 1500 D, although this figure is no more than a guide-line. They may for instance be chosen from the following list: diyn-ene- toxins like calicheamicins, esperamycins and dynemicin A, tricothecenes like verrucarin A, deoxyverrucarol, roridin A and diacetoxyscirpenol and mycotoxin. Especially preferred are calicheamicin and verrucarin A. Of course it is also possible to use radionuclides as cytotoxic moieties.
• the toxins and (proteinaceous) molecules according to the invention may be coupled to each other in any suitable way. Both the (proteinaceous) molecules and the toxins have sufficient reactive groups so as to introduce reactive groups that they may be coupled without a substantial detrimental effect to their respective activities. Alternatively the linkage between the toxin and targeting moiety may be broken upon localization or internalization of the conjugate.
• the coupling may be either direct or through a linking molecule and/or a spacer.
• the invention also relates to pharmaceutical compositions comprising the targeted toxin molecules according to the invention.
• Obvious routes of administration for the compounds of the invention would be intra-articular or parenteral administration whereby the targeted toxin molecules are dissolved or emulsified in a suitable vehicle for injection.
• a suitable vehicle for injection Apart from this vehicle the composition may of course contain the other usual additives.
• the therapeutic dose of the conjugates according to the invention will vary with the molecular weight of the conjugates. It may range from 10 ⁇ g to 500 mg per injection in systemic applications. In local applications it may be even lower than that.
• the conjugates were made by adding VAONSu (lmg/ml, DMF) to the protein
• the peptide conjugates were purified by adding a 20 fold excess ethyl-acetate (vol/vol) . After centrifugation, the precipitate was dissolved in PBS buffer. This was done for the p20 peptide, the internalizing part of (IL-2) and the J6-peptide.
• Verrucarin -A-hydrazide was linked to carbohy ⁇ drate groups on Transferrin.
• the carbohydrate groups were oxidised by adding 10 mM NaI04 to Transferrin, dissolved in 0.1 M NaOAc pH 5.5. After 10 min. Na2S03 was added in order to remove excess NaI04. Then V-A-hydrazide was added (concentration 1 mM) . After 1 hour incubation the conjugate was purified on a PD 10 column, equilibrated in PBS buffer. 4 . 2 Tests .
• a . 2 . 1 A human T cell clone (Reiz 1F9) was cultured together with the various Verrucarin A con ⁇ jugates in M505 medium supplemented with 10 % human pool serum, 2 mM glutamine, 20 /xM ⁇ - mercaptoethanol and antibiotics (200 U/ml penicillin, 100 mg/ml streptomycin) . After 2 h. of incubation the conjugates were removed by washing the cells with medium. Cells were then cultured in the presence of 20 U recombinant IL-2 at 37 C, in a humid 5 % C0 2 atmosphere for 72 hr. 3H-Thymidine (0.1 ⁇ Ci/well) was then added and after an overnight incubation the cells were harvested and the incorporation of radioactivity was counted with a Packard beta counter.
• PANC cells were grown in M505 + 10 % FCS. For testing, the PANC cells were cultured in microtiter plates (1000 cells/well, 100 uL) .
• the absorbance at 540 n was read in an ELISA reader.
• 4.2.3 Leydig cells were isolated from the testes of mature Swiss mice (9 to 13 weeks old) . The cells were obtained by sucking each decapsu- lated testis 5 times through a glass tube and filtering the suspension through a 30 ⁇ m nylon mesh. The cells were suspended in M199 supplemented with 4.2 mM NaHCO ⁇ , 20 ml/1 fetal calf serum and 1 g/1 BSA and 100 ⁇ l cell suspension was added to each well of a microtiter plate along with 50 ⁇ l test sample. Plates were incubated for 4 h at 37 C in a humid atmosphere of 5 % C0 2 -95 % air subsequently stored at -20°C until testosterone determination by RIA.
• Fig. 3 shows that the P20-VA conjugate reduces the proliferation of the T cell clone at relatively high concentrations, when compared to VA alone; P20 itself has no effects, indicating the specific toxicity of the conjugate; the binding affinity of P20 to the IL-2 receptor is relatively low, explai ⁇ ning the relatively high concentrations requi ⁇ red for the toxic effects.
• Fig. 4 shows that the J-6-VA conjugates kills the cell clone at very low concentrations (0.02-0,05 ⁇ M) , indicating very specific and efficient killing. At very high concentrarions the J-6 peptide itself generates some well known cytotoxic effects.
• VA-ONSU ester retains full toxi ⁇ city of VA alone. If VA is conjugated to epi ⁇ dermal growth factor (fig. 5) or transferrin (fig. 6-7) specific inhibition of the growth of the PANC cells is found. The ligands themselves have no effects.
• hCG-VA conjugates In yet another model system we tested the hCG- VA conjugates. After 4 h of incubation, hCG clearly stimulates - as expected - the testos ⁇ terone production in mouse Leydig cells to the relative amount of about 600 ng/ l. Incubation with hCG-VA (1 mg/ml) significantly reduced the testosterone production in mouse Leydig cells.

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• 1991
  • 1991-06-21 CA CA002086679A patent/CA2086679A1/en not_active Abandoned
  • 1991-06-21 WO PCT/EP1991/001169 patent/WO1992000762A1/en not_active Application Discontinuation
  • 1991-06-21 JP JP91511341A patent/JPH05508634A/ja active Pending
  • 1991-06-21 AU AU80606/91A patent/AU657910B2/en not_active Ceased
  • 1991-06-21 EP EP91912210A patent/EP0537229A1/de not_active Withdrawn
  • 1991-06-21 IE IE216791A patent/IE912167A1/en unknown
  • 1991-06-26 ZA ZA914933A patent/ZA914933B/xx unknown

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