PHARMACEUTICAL PREPARATION

Abstract

The present invention provides a method for generating purified solution of at least on alpha-emitting radionuclide complex. The method comprises contacting a solution of the alpha-emitting radionuclide complex and at least one daughter nuclide with at least one selective binder for the daughter nuclide and subsequently separating the solution from the selective binder. The invention also provides a method for the removal of at least one daughter radionuclide from a solution comprising at least one alpha-emitting radionuclide complex. The method comprises contacting the solution with at least one selective binder for the daughter nuclide.

Claims

1. A method for generating a purified solution of at least one alpha-emitting radionuclide, said method comprising contacting a solution comprising said least one alpha-emitting radionuclide complex and at least one daughter nuclide with at least one selective binder for said at least one daughter nuclide and subsequently separating said solution of at least one alpha-emitting radionuclide complex from said at least one selective binder.

2. A method for reducing the radiolysis of at least one organic component in a solution comprising at least one alpha-emitting radionuclide complex, at least one daughter radionuclide and at least one organic component, said method comprising contacting said solution with at least one selective binder for said at least one daughter nuclide.

3. A method for the removal of at least one daughter radionuclide from a solution comprising at least one alpha-emitting radionuclide complex, said method comprising contacting said solution with at least one selective binder for said at least one daughter nuclide.

4. A method as claimed in claim 3 wherein said solution is a pharmaceutical preparation.

5. A method as claimed in claim 3 further comprising separating said solution from said selective binder.

6. A method as claimed in claim 3 wherein said alpha-emitting radionuclide is in the form of a complex with a ligand, wherein said ligand is conjugated to a specific binding moiety (such as an antibody).

7. A method as claimed in claim 3 wherein said selective binder is in the form of, or is attached to, a solid support or gel support.

8. A method as claimed in claim 7 wherein said solid or gel support is in the form of, or attached to, least one selected from membranes, resin beads, gel beads, self-assembled lipid structures (e.g. liposomes), microparticles, nanoparticles, powders, crystals, ceramics and polymer structures.

9. A method as claimed in claim 3 wherein said selective binder comprises at least one selected from cation exchange resins, size exclusion resins, zeolites, molecular sieves, hydroxyapatite, alginates, liposomes, phosphonates, polyphosphonates, phospholipids, glycolipids, lipo-proteins, oligosaccharides, ferritin, transferrin, phytic acid and co-precipitation agents.

10. A method as claimed in claim 3 wherein said solution is contacted with said selective binder by means of flow of said solution through or past said selective binder or through or past a support upon which said selective binder is immobilised.

11. A method as claimed in claim 10 wherein said contacting is by means of a filtration in which said solution flows through or past said selective binder or through or past a support upon which said selective binder is immobilised.

12. A method as claimed in claim 11 wherein said filtration further comprises flowing said solution through a sterile filtration membrane.

13. A method as claimed in claim 3 wherein said contacting takes place for a period of less than 30 minutes, such as less than 10 minutes, e.g. less than 5 minutes or less than 1 minute (e.g. no more than 30 seconds).

14. A method as claimed in claim 3 wherein said solution is contacted with said selective binder by means of addition of said selective binder and said solution to a vessel (e.g. a sealed or partially sealed vessel).

15. A method as claimed in claim 14 wherein said contacting takes place for 30 minutes or longer, (e.g. 1 hour or longer, such as 1 day or longer).

16. A method as claimed in claim 3 wherein said alpha-emitting radioisotope is comprises at least one alpha-emitting thorium isotope, such as .sup.227Th.

17. A method as claimed in claim 3 wherein said at least one daughter nuclide comprises at least one radium isotope, such as .sup.223Ra.

18. A kit for the formation of a pharmaceutical preparation of at least one alpha-emitting radioisotope complex, said kit comprising: i) a solution of said at least one alpha-emitting radioisotope and at least one daughter isotope; ii) at least one ligand; ii) a specific binding moiety; iii) at least one selective binder for said at least one daughter isotope. wherein said alpha-emitting radioisotope is complexed or complexable by said ligand which is conjugated or conjugatable to said specific binding moiety.

19. A kit as claimed in claim 18 wherein said solution of said at least one alpha-emitting radioisotope and at least one daughter isotope is present in a first vessel (e.g. vial, syringe etc) and said ligand conjugated to said specific binding moiety is present in a second vessel.

20. A kit as claimed in claim 18 wherein said selective binder is present in the form of at least one filter, such as a syringe filter, through which said solution of alpha-emitting radioisotope can be passed after complexation by said ligand and optionally after conjugation to said specific binding moiety.

21. A kit as claimed in claim 18 wherein said selective binder is present in the form of or attached to at least one solid or gel support.

22. A kit as claimed in claim 21 wherein said selective binder is present in said first vessel.

23. A kit as claimed in claim 18 wherein said selective binder is separated from said solution by the process of administration of said solution.

24. A kit as claimed in claim 21 wherein said solid or gel support is least one selected from membranes, resin beads, gel beads, self-assembled lipid structures (e.g. liposomes), microparticles, nanoparticles, powders, crystals and polymer structures.

25. A kit as claimed in claim 18 wherein said selective binder comprises at least one selected from cation exchange resins, size exclusion resins, zeolites, molecular sieves, hydroxyapatite, alginates, liposomes, phosphonates, polyphosphonates, phospholipids, glycolipids, lipo-proteins, oligosaccharides, ferritin, transferrin, phytic acid and co-precipitation agents.

26. A kit as claimed claim 18 wherein said alpha-emitting radioisotope is at least one thorium radioisotope such as .sup.227Th.

27. A kit as claimed in claim 18 wherein said daughter isotope is at least one radium isotope, such as .sup.223Ra.

28. A kit as claimed in claim 18 additionally comprising a filter and/or an administration device.

29. A kit as claimed in claim 28 wherein the filter has a pore size of no larger than 0.22 μm

30. An administration device comprising a solution of at least one alpha-emitting radionuclide complex and at least one daughter nuclide, said device further comprising a filter containing at least one selective binder for said daughter nuclide.

31. A device as claimed in claim 30 in the form of a disposable syringe and syringe filter.

32. A kit as claimed in claim 18 further comprising (a) an administration device comprising a solution of at least one complexed alpha-emitting radionuclide and at least one daughter nuclide, and (b) a selective binder for said daughter nuclide in the form of a filter.

33. A method for the formation of an injectable solution of an alpha-radionuclide complex comprises the steps of: a) combining a first solution comprising a dissolved salt of an alpha-emitting radionuclide and at least one daughter nuclide with a second solution comprising at least one ligand conjugated to at least one targeting moiety; b) incubating the combined solutions at a suitable temperature (e.g. 0° C. to 50° C., preferably 20° C. to 40° C.) for a period to allow complex formation between said ligand and said alpha-emitting radioisotope whereby to form a solution of at least one alpha-emitting radioisotope complex; c) contacting said solution of at least one alpha-emitting radioisotope complex with at least one selective binder for at least one of said daughter nuclides. d) separating said solution of at least one alpha-emitting radionuclide complex from said at least one selective binder.

34. (canceled)

Description

[0074] The invention will now be illustrated by reference to the following non-limiting Examples, and the FIGURES below, in which:

[0075] FIG. 1 shows the generation of hydrogen peroxide by radiolysis of water in the presence or absence of a selective binder

EXAMPLE 1

Radium-223 Uptake on Gravity Columns Using Ceramic Hydroxyapatite

[0076] 100 mg ceramic hydroxyapatite was weighed out and transferred to the columns. HEPES buffer (5 mM, pH 8) was used to equilibrate the column (3×1 ml). 1 ml HEPES buffer was then added to the column which was left standing over night before 140 kBq radium-223 in 1 mL was loaded. Uptake was immediate. The column was then washed with HEPES buffer (3×1 ml), before uptake of radium-223 on the column material was determined using a HPGe-detector instrument (Ortec, Oak Ridge, Tenn.).

[0077] The material removed 98.9% of radium-223 and daughter nuclides (Table 2).

TABLE-US-00002 TABLE 2 Average percentage retention of radium- 223 for ceramic hydroxyapatite (n = 3). Samples Average retention of radium-223 (%) Ceramic hydroxyapatite 98.9

EXAMPLE 2

[0078] Purification of a Targeted Thorium Conjugate in Phosphate Buffer on Spin Columns with Propylsulfonic Acid Silica Based Cation Exchange Resin

[0079] A trastuzumab chelator conjugate prepared as described previously (WO2011/098611A) was labeled with thorium-227 (forming a Targeted Thorium Conjugate, TTC), using thorium-227 stored for 5 days in HCl following purification and hence containing ingrown radium-223 and progenies of radium-223 decay. Each sample contained 0.21 mg TTC, 520 kBq thorium-227 and 160 kBq radium-223 in 300 μl saline phosphate buffer pH 7.4 (Biochrome PBS Dulbecco, Cat no L1825). The sample was added to a column with 15 mg propylsulfonic acid silica based cation exchange resin. The columns were centrifuged (10 000 rcf, 1 min) and the eluate collected. The distribution of thorium-227 (TTC) and radium-223 between the column and eluate was determined using a HPGe-detector instrument (Ortec, Oak Ridge, Tenn.).

[0080] The retention of TTC (represented by thorium-227) and radium-223 on the column was 5.5 and 99.1%, respectively (Table 3).

TABLE-US-00003 TABLE 3 Retention of Targeted Thorium Conjugate (TTC) and radium-223 after purification on spin columns with cation exchange resin Amount of cation exchange resin (mg) TTC on column (%) radium-223 on column (%) 15 5.5 99.1

EXAMPLE 3

[0081] Removal of Radium-223 in Citrate and Phosphate Buffer on Spin Columns with Propylsulfonic Acid Silica based Cation Exchange Resin

[0082] 160 kBq radium-223 in 300 μl 50 mM citrate buffer pH 5.5 with 0.9% sodium chloride or saline phosphate buffer pH 7.4 (Biochrome PBS Dulbecco, Cat no L1825) was added to a column with 60 mg propylsulfonic acid silica based cation exchange resin. The columns were then centrifuged (10 000 rcf, 1 min) and the eluate collected. The distribution of radium-223 between the column and eluate was determined using a HPGe-detector instrument (Ortec, Oak Ridge, Tenn.).

[0083] The retention of radium-223 on the column was 96.5% for the citrate buffer and 99.6% for the phosphate buffer, respectively (Table 3).

TABLE-US-00004 TABLE 3 Retention of radium-223 after purification on spin columns with cation exchange resin Buffer type Average radium-223 on column (%) Citrate 96.5 phosphate 99.6

EXAMPLE 4—FURTHER COMPARISON OF SELECTIVE BINDER MATERIALS

[0084] Strontium and calcium alginate gel beads, DSPG liposomes, ceramic hydroxyapatite, Zeolite UOP type 4A, and two cation exchange resins (AG50WX8 and SOURCE 30 S) were selected as materials to be studied for radium-223 uptake. Passive diffusional uptake of nuclides was tested by having materials present as suspensions in the formulation. Measurements were taken with the aid of a Germanium detector after 1 hour equilibration at 25° C. with shaking. Removal of free nuclides on gravity columns was also studied.

Uptake of Radium-223

[0085] All materials, to some degree, removed radium-223 and daughters by passive diffusional uptake ranging from 30.8±5.8 to 95.4±2.5% uptake at the selected experimental conditions. All the materials tested removed radium-223 and daughters on the gravity column set-up with near complete uptake. The results were significantly higher (˜100%) and with minimal variation (<1%) compared to passive diffusional uptake of radium-223, for all tested materials except for alginate gel beads (see Table 4).

TABLE-US-00005 Relative Relative standard Standard Average deviation Average deviation uptake of uptake of uptake of uptake of radium-223 radium-223 radium-223 radium-223 by passive by passive on gravity on gravity Samples diffusion (%) diffusion (%) column (%) column (%) Liposomes 95.4 2.5 — — SOURCE 78.7 15.8 99.5 0.1 30S cation exchange resins Ceramic 77.8 20.1 98.9 0.7 hydroxyapatite Calcium 71.9 9.7  8.2 20.7  alginate gel beads Strontium 68.2 16.7 — — alginate gel beads Zeolite UOP 49.7 7.4 — — type 4A Calcium 33.1 1.7 — — alginate gel beads AG50WX8 30.8 5.8 99.8 0.2 cation exchange resins

[0086] Various materials suitable for capturing radium-223 daughter isotopes have been identified. Strontium and calcium alginate gel beads, DSPG liposomes, ceramic hydroxyapatite, Zeolite UOP type 4A, and two cation exchange resins (AG50WX8 and SOURCE 30 S) were tested and all materials were found to remove radium-223 and daughters.

[0087] DSPG liposomes were superior when testing passive diffusional uptake while the other materials were suboptimal when used as suspensions and for uptake by passive diffusion. The cation exchange resins and ceramic hydroxyapatite were however excellent when used on gravity columns.

EXAMPLE 5—REDUCTION IN RADIOLYSIS

Abstract

[0088] Formation of hydrogen peroxide (H.sub.2O.sub.2) in the water phase of the formulation was studied as a measure of radiolysis in the presence and absence of ceramic hydroxyapatite, which was one of the materials shown to efficiently bind the radionuclides from solution. Radiolysis and formation of free radicals in the water phase may degrade the radionuclide complex thus minimization of the generation and amount of H.sub.2O.sub.2 present is desirable. After 3 days the concentration of H.sub.2O.sub.2 in samples with ceramic hydroxyapatite was significantly lower than the controls, and the uptake of .sup.223Ra and .sup.227Th from solution was near complete.

Method

[0089] The UVmini-1240 single beam spectrophotometer (190-1100 nm) from Shimadzo (Kyoto, Japan) was used and light transmittance recorded at 730 nm for analyzes of the H.sub.2O.sub.2 concentration. Photometric mode was used where the absorbance of a sample is measured at a fixed wavelength (n=3). The cuvettes used were Plastibrand disposable 1.5 ml semi-micro (12.5×12.5×45 mm) cuvettes made of polystyrene.

[0090] A 0.5 mg/ml horseradish peroxidase solution and 2 mg/ml peroxidase substrate (2.2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) solution were made by dissolution in metal free water. The peroxidase enzyme converts the peroxidase substrate from colorless to a green color with H.sub.2O.sub.2 as substrate. H.sub.2O.sub.2 standards at 1.765, 0.882, 0.441, 0.221, and 0.110 mmol/L H.sub.2O.sub.2 were made by diluting 30% (w/w) H.sub.2O.sub.2 in metal free water (n=3). The linearity of the standard curve was R.sup.2=0.9995.

[0091] Samples consisted of 100 mg/ml ceramic hydroxyapatite in 250 μl 9 mg/ml sodium chloride which was loaded with a freshly prepared .sup.227Th solution to a concentration of 0.5 kBq/μl (n=3).

[0092] Two types of control samples were analyzed; one negative control with only .sup.227Th and no binding material, and one positive control with binding material but no radioactive source (n=3). The negative controls were analyzed to check the homogeneity of the radionuclides in the sodium chloride solution and the amount of H.sub.2O.sub.2 generated in the absence of binding material, while the positive controls were analyzed to see if a significant level of H.sub.2O.sub.2 was developed without the presence of radioactivity.

[0093] For calculation of the percentage uptake of radionuclides in ceramic hydroxyapatite samples and homogeneity of radionuclides in the negative controls, each sample or control was measured on the HPGe-detector before 60 μl supernatant was removed. Samples, controls and standards were further prepared for H.sub.2O.sub.2 analysis by mixing 900 μl 9 mg/ml sodium chloride with 50 μl peroxidase substrate solution, 25 μl horseradish peroxidase solution and 25 μl of the respective supernatant from sample, control or standard. The samples, control or standard were carefully mixed and measured immediately by UV-vis spectrophotometry. For radioactive samples and controls, the remaining sample volume was finally measured on the HPGe-detector. Uptake of radionuclides in ceramic hydroxyapatite or homogeneity of radioactivity in the sodium chloride solution was calculated by the aid of HPGe-spectra.

[0094] H.sub.2O.sub.2 concentration in the samples, standards and controls were analyzed by UV-vis spectrophotometry at 730 nm, at time points 0, 3, 7, 10 and 14 days.

Results

[0095] The measured level of H.sub.2O.sub.2 formed during 14 days storage in samples of suspended ceramic hydroxyapatite and freshly prepared .sup.227Th was significantly lowered compared to negative controls without ceramic hydroxyapatite (FIG. 1). The positive controls containing ceramic hydroxyapatite without radioactivity did not show any H.sub.2O.sub.2 formation outside the statistical error of the method (FIG. 1). The passive diffusional uptake of freshly prepared .sup.227Th in a suspension of ceramic hydroxyapatite was 81±3% at 90 minutes reaction time. The consecutive uptake of .sup.227Th and generated .sup.223Ra by ceramic hydroxyapatite was 99±5% and 102±12%, respectively, when measured after 14 days incubation.

[0096] The measured reduction in H.sub.2O.sub.2 demonstrates a reduced production of radicals and oxidising agents due to radiolysis of the containing solution.