A method for radiolabeling process for the preparation of PSMA-617 molecule radiolabeled with [ 161tb]tb (terbium-161)

Abstract

The invention belongs to the technical field of radiopharmaceutical production and is related to a method for performing radiolabeling process with high efficiency by optimizing the process steps in radiolabeling processes of the PSMA-617 agents with terbium-161.

Description

[0001] A METHOD FOR RADIOLABELING PROCESS FOR THE PREPARATION OF PSMA-617 MOLECULE RADIOLABELED WITH [161Tb]Tb (TERBIUM-161)

[0002] TECHNICAL FIELD

[0003] The invention belongs to the technical field of radiopharmaceutical production and is related to a method for performing radiolabeling process with high efficiency by optimizing the radiolabeling process of the PSMA-617 agent with terbium-161 (abbreviated as Tb-161 or161Tb).

[0004] PRIOR ART

[0005] Terbium is an element found in the 65th row of the periodic table and its symbol is Tb. Terbium has different isotopes, however Terbium-161 stands out as an isotope used in nuclear medicine and radiotherapy applications. Terbium-161 is used especially in the treatment of neuroendocrine tumors and some types of cancer, such as prostate cancer. It targets tumor cells by emitting beta particles during radioactive decay and thus facilitates cancer treatment.

[0006] Terbium-161 is used for isotope monitoring or labeling in many applications where objects or organisms need to be monitored or tracked. It is used for monitoring, detection and analysis of biological samples and molecules, especially in laboratory research. This is important for molecular biology, biochemistry, and biomedical research.

[0007] PSMA-617 is the name of a radiopharmaceutical or radiopharmaceutical agent that targets prostate-specific membrane antigen. Prostate-specific membrane antigen is a protein found mainly in prostate cancer cells. PSMA-617 is a compound containing a radioactive isotope used in the detection and treatment of prostate cancer. This agent plays an important role in radiotherapy and nuclear medicine applications. PSMA-617 is especially used in the treatment of metastatic prostate cancer. This substance targets the PSMA protein and can bind to prostate cancer cells in a more specific way. PSMA-617 comprises a radioactive isotope when it binds to prostate cancer cells. In this way, radiation is delivered directly to prostate cancer cells and aids in the killing of cancer cells.

[0008] The radioactive isotope contained in PSMA-617 is usually Terbium-161. Terbium-161 PSMA treatment may be an option in the treatment of advanced prostate cancer. This treatment is used in patients with metastatic prostate cancer and includes targeted radioactive treatment with PSMA-617.

[0009] It is important that radiopharmaceutical agents are subjected to radiolabeling processes with high efficiency. This is because radiolabeling processes that are not performed with high efficiency can cause high costs, increased radiation exposure, increased waste generation, low product efficiency, and difficulty in their use in radiotherapy or imaging studies.

[0010] Research and development activities are required in order to perform radiolabeling processes of PSMA-617 agents, which are frequently used in prostate cancer treatments, with Terbium-161 at higher efficiency than the methods known in the art.

[0011] SUMMARY OF THE INVENTION

[0012] In the relevant technical field, the following two methods are frequently applied in the radiolabeling of the PSMA-617 agent with Tb-161 (161Tb-PSMA-617).

[0013] Method 1 :

[0014] Buffer Solution Preparation

[0015] Solution A: It is prepared by dissolving 4.102 g of sodium acetate in 50 mL of water. Solution B: It is prepared by adding ultra-pure water to 2,850 mL of acetic acid to a final volume of 50 mL. 25 mL of solution A and 25 mL of solution B are mixed and adjusted to pH= 4,5. Radiolabeling: 1 mL of sodium acetate buffer is added to the tube containing 50 pL of Ascorbic acid and mixed. The obtained mixture is added to the 2nd tube containing 25 pL of PSMA-617, and upon mixing, 5 mCi of [161Tb]TbCl3 is added. The mixture is stirred at 95°C for ~25 minutes and then cooled at room temperature. Method 2: To work with 100 MBq / nmol specific activity,161TbCh (5 mCi) is added to 25 pL of PSMA-617 containing sodium acetate (0,5 M, pH ~ 8) and incubated at 95 °C (pH 4.5) for 10 minutes.

[0016] It was determined that the chromatograms of161TbCh,161Tb-PSMA-617,161Tb+3compounds were not sufficiently separated in TLRC (Thin Layer Radio Chromatography) and HPLRC (High Performance Liquid Radio Chromatography) methods of the products obtained as a result of the radiolabeling processes obtained in both of said methods. For this reason, it has been determined that high-efficiency radiolabeling processes cannot be performed in these applied methods.

[0017] In response to the technical problem mentioned here, the inventors of the present invention have introduced a method for performing radiolabeling processes with high efficiency for the relevant technical field. With the method characterized in the invention, it is possible to radiolabel the PSMA-617 agent with161Tb with high efficiency.

[0018] BRIEF DESCRIPTION OF DRAWINGS

[0019] In Figure 1 , TLRC chromatograms of161TbCh,161Tb-PSMA-617,161Tb+3compounds obtained by the method of the present invention are shared.

[0020] In Figure 2, HPLRC chromatograms of161TbCh,161Tb-PSMA-617,161Tb+3compounds obtained by the method of the present invention are shared.

[0021] DETAILED DESCRIPTION OF THE INVENTION

[0022] In this detailed description, the subject of the invention relates to a method for radiolabeling PSMA-617 agents with Tb-161 and is described by way of non-limiting examples only for a better understanding of the subject matter.

[0023] In the invention, radiolabeling process refers to a process or technique used to add or bind a radioactive isotope to an object or molecule. This process is particularly used in medical applications. In this invention, radiolabeling with high efficiency refers to obtaining a ratio of 97,99% ± 2,01 (n = 3) as a result of the processes performed. The efficiency here is determined by TRLC and HPLRC assay methods.

[0024] In the method of the invention, as the first process step, oxidation reactions are carried out for the production of161Tb+3by incubation processes from commercially available161TbCh mixtures. With the applied process step, the following oxidation reaction is carried out.

[0025] TbCI3161Tb+3+ 3CI-

[0026] Equation 1.

[0027] The reason for performing this step is to ensure that the oxidized161Tb+3ions are in contact with the chelates attached to the PSMA molecule (DOTA) for direct radiolabeling reactions and to facilitate their interaction with each other to facilitate the formation of complex compounds.

[0028] To perform this process step, a reaction mixture is obtained by adding 1 to 2 mL of sodium acetate buffer solution and 5 to 10 mCi161TbCh to a tube containing ascorbic acid in the range of 50 to 100 pL. Said reaction mixture has a pH value of 4,5. In the obtained reaction mixture, incubation processes are carried out to perform Equation 1. Said incubation processes take place in a temperature range between 92 to 96 °C. The ideal temperature value for said incubation processes is 95 °C. The duration of the incubation process is between 5 to 15 minutes. In a preferred embodiment, the incubation process continues for 10 minutes. The duration and temperature values characterized here are the parameters determined for oxidation reactions necessary for radiochemical reactions to take place at targeted efficiencies.

[0029] As the next process step, second incubation processes are carried out by adding PSMA-617 agents at a value in the range of 10 to 30 pL for radiolabeling processes to the reaction mixture where Equation 1 takes place. The values mentioned here are determined to carry out the reaction in stoichiometric ratios. Normally, the reactions require the addition of raw materials in a ratio of significantly more than 1 :1. In the method of the invention, this value is adjusted so that the161Tb+3: PSMA-617 ratio is 1 :1. In this way, technical problems such as high costs of sourcing raw materials and the subsequent formation of by-products are eliminated.

[0030] In this invention, second incubation process takes place in a temperature range between 92 to 96 °C. The ideal temperature value for said incubation processes is 95 °C. The duration of the incubation process is between 20 to 30 minutes. In a preferred embodiment, the incubation process continues for 25 minutes. The temperatures and durations characterized here are the values obtained after carrying out radiochemical reactions at the targeted efficiency.

[0031] As a result of carrying out the second incubation processes, the products obtained are cooled to room temperature for at least 5 minutes.

[0032] The total application duration of the method characterized in the invention is about 40 minutes. As a result of the processes, the efficiency of radiolabeling processes of PSMA-617 agents with161Tb+3is 97,99% ± 2,01% (n=3).

[0033] The products obtained are subjected to the relevant quality control processes. Said quality control processes are TLRC and HPLRC methods.

[0034] Quality control analysis with TLC method

[0035] For the TLRC, a silica gel TLC strip and ammonium acetate 1 M: methanol (1 :1 v / v) mobile phase system were used.

[0036] TLRC chromatograms of 161TbCh,161Tb- PSMA-617,161Tb+3compounds are shown in Figure 1.

[0037] As can be seen in Figure 1 , the Rf values of161TbCh,161Tb-PSMA-617,61Tb+3substances were 0,053, 0,0425, and 0,073, respectively, and it was determined that the radiolabeling study was successfully performed with a radiolabeling efficiency of 97,99 ± 2,01% (n=3).

[0038] Quality control analysis with HPLRC method The HPLRC system used ODS 5-pm C18 RP-C18 (250 x 4,6 mm ID) (GL Sciences Inc.) column, Shimadzu LC-10Atvp (SPD-10AV) HPLC system, and Nal (Tl) detector (Gabi Star, Raytest). Solutions with 0,1% trifluoroacetic acid in MiliQ water (A) and acetonitrile (B) as the mobile phase were used at a flow rate of 1 mL / min using gradient A (95%-20% for 15 min) and gradient B for 15 minutes.

[0039] Figure 2 shows HPLRC chromatograms. In radiopharmaceutical research, the radiolabeling efficiency of radiopharmaceuticals is expected to be over 95%. As a result, it was determined that161Tb-PSMA-617 was successfully prepared with a radiolabeling efficiency of 97,99% ± 2,01 (n=3) using the newly developed said process of the invention

[0040] The protection scope of the invention is specified in the appended claims and cannot be limited to what is described for illustrative purposes in this detailed description. It is clear that a person skilled in the art can produce similar embodiments in the light of what is explained above, without deviating from the main theme of the invention.

Claims

CLAIMS1. A method for radiolabeling PSMA-617 agents with terbium-161 isotopes, particularly suitable for use in the field of radiopharmaceutical technology, characterized in that it comprises the process steps of:- subjecting the supplied [161Tb]TbCh solution to the first incubation processes and performing the oxidation reaction of ([161Tb]Tb)+3given below as Equation 1 ,[TbCI3] ([161Tb]Tb)+3+ 3ChEquation 1- adding the solution containing PSMA-617 agents to ensure the interaction of ([161Tb]Tb)+3ions with PSMA-617 agents and performing second incubation processes- performing cooling processes to room temperature.

2. A method according to claim 1 , characterized in that the said [161Tb]TbCh solution comprises [161Tb]TbCh at a value in the range of 5 to 10 mCi.

3. A method according to claim 1 or claim 2, characterized in that the amount of PSMA-617 agent in the solution containing the PSMA-617 agent is at a value in the range of 10 to 30 pL.

4. A method according to any one of the preceding claims, characterized in that the solution in which the [161Tb]TbCh second incubation is to be performed comprises [161Tb]TbCh and PSMA-617 in a ratio of 1 :1 by weight.

5. A method according to any one of the preceding claims, characterized in that the temperature of said first incubation process is a value between 92 to 96 °C.

6. A method according to any one of the preceding claims, characterized in that the duration of said first incubation process is a value between 5 to 15 minutes.

7. A method according to any one of the preceding claims, characterized in that the pH of the reaction medium in said first incubation process is 4,5.

8. A method according to any one of the preceding claims, characterized in that the temperature of said second incubation process is a value between 92 to 96°C.

9. A method according to any one of the preceding claims, characterized in that the duration of said second incubation process is a value between 20 to 30 minutes.

10. A PSMA-617 radiolabeled with ([161Tb]Tb)+3obtained by a method according to any one of the preceding claims and having radiolabeling process efficiency of 97,99 ± 2,01% (n=3).

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