Automated synthesis of 68 Ga/177 Lu-PSMA on the Trasis miniAllinOne

"One Method to Label Them All": A Single Fully Automated Protocol for GMP-Compliant 68Ga Radiolabeling of PSMA-11, Transposable to PSMA-I&T and PSMA-617

BACKGROUND

Prostate-specific membrane antigen (PSMA) is an ideal target for molecular imaging and targeted radionuclide therapy in prostate cancer. Consequently, various PSMA ligands were developed. Some of these molecules are functionalized with a chelator that can host radiometals, such as 68Ga for PET imaging. The 68Ga radiolabeling step benefits from process automation, making it more robust and reducing radiation exposure.

OBJECTIVE

To design a single automated radiolabeling protocol for the GMP-compliant preparation of [68Ga]Ga-PSMA-11, transposable to the production of [68Ga]Ga-PSMA-617 and [68Ga]Ga-PSMA-I&T.

METHODS

A GAIA® synthesis module and a GALLIAD® generator were used. Radio-TLC and radio-HPLC methods were validated for radiochemical purity (RCP) determination. Three [68Ga]Ga-PSMA-11 validation batches were produced and thoroughly tested for appearance and pH, radionuclide identity and purity, RCP, stability, residual solvent and sterility. Minimal modifications were made to the reagents and disposables for optimal application to other PSMA ligands.

RESULTS

[68Ga]Ga-PSMA-11 for clinical application was produced in 27 min. The 3 validation batches met the quality criteria expected by the European Pharmacopoeia to allow routine production. For optimal transposition to PSMA-617, the solid phase extraction cartridge was changed to improve purification of the radiolabeled product. For application to PSMA-I&T, the buffer solution initially used was replaced by HEPES 2.7 M to achieve good radiochemical yields. Residual HEPES content was checked in the final product and was below the Ph. Eur. threshold.

CONCLUSION

A single automated radiolabeling method on the GAIA® module was developed and implemented for 68Ga radiolabeling of 3 PSMA ligands, with slight adjustments for each molecule.

[68 Ga]Ga-PentixaFor: Development of a fully automated in hospital production on the Trasis miniAllinOne synthesizer

[68 Ga]Ga-PentixaFor is a frequently used radiotracer to image the CXCR4/CXCL12 axis in various malignancies, infections, and cardiovascular diseases. To answer increasing clinical needs, an automatized synthesis process ensuring efficient and reproducible production and improving operator's radioprotection is needed. [68 Ga]Ga-PentixaFor synthesis has been described on other synthesizers but not on the miniAiO. In this work, we defined automated synthesis process and an analytical method for the quality control of [68 Ga]Ga-PentixaFor. Validation batches were performed under aseptic conditions in a class A hotcell. All the quality controls required by the European Pharmacopea (Eur. Ph) were performed. The analytical methods were validated according to the International Conference Harmonization (ICH) recommendations. Validation batches were performed with a radiochemical yield of 94.8 ± 2.6%. All the quality controls were in conformity with the Eur. Ph, and the validation of the analytical method complied with the ICH. The environmental monitoring performed during the synthesis process showed that the aseptic conditions were ensured. [68 Ga]Ga-PentixaFor was successfully synthesized with the miniAiO by a fully automated process. This robust production mode and the quality control have been validated in this study allowing to increase the access of patients to this new promising radiopharmaceutical.

Innovation in Radionuclide Therapy for the Treatment of Prostate Cancers: Radiochemical Perspective and Recent Therapeutic Practices

Prostate cancer represents the second cause of death by cancer in males in western countries. While early-stage diseases are accessible to surgery and/or external radiotherapy, advanced metastatic prostate cancers are primarily treated with androgen deprivation therapy, to which new generation androgen receptor antagonists or taxane-based chemotherapies are added in the case of tumor relapse. Nevertheless, patients become invariably resistant to castration with a median survival that rarely exceeds 3 years. This fostered the search for alternative strategies, independent of the androgen receptor signaling pathway. In this line, radionuclide therapies may represent an interesting option as they could target either the microenvironment of sclerotic bone metastases with the use of radiopharmaceuticals containing samarium-153, strontium-89 or radium-223 or tumor cells expressing the prostate-specific membrane antigen (PSMA), a protein found at the surface of prostate cancer cells. This review gives highlights the chemical properties of radioligands targeting prostate cancer cells and recapitulates the clinical trials evaluating the efficacy of radionuclide therapies, alone or in combination with other approved treatments, in patients with castration-resistant prostate tumors. It discusses some of the encouraging results obtained, especially the benefit on overall survival that was reported with [¹⁷⁷Lu]-PSMA-617. It also addresses the specific requirements for the use of this particular class of drugs, both in terms of medical staff coordination and adapted infrastructures for efficient radioprotection.

Fully Automated Macro- and Microfluidic Production of [68Ga]Ga-Citrate on mAIO® and iMiDEVTM Modules

⁶⁸Ga-radionuclide has gained importance due to its availability via ⁶⁸Ge/⁶⁸Ga generator or cyclotron production, therefore increasing the number of ⁶⁸Ga-based PET radiopharmaceuticals available in clinical practice. [⁶⁸Ga]Ga-citrate PET has been shown to be prominent for detection of inflammation/infection of the musculoskeletal, gastrointestinal, respiratory, and cardiovascular systems. Automation and comparison between conventional and microfluidic production of [⁶⁸Ga]Ga-citrate was performed using miniAllInOne^® (Trasis) and iMiDEV™ (PMB-Alcen) synthetic modules. Fully automated procedures were elaborated for cGMP production of tracer. In order to facilitate the tracer approval as a radiopharmaceutical for clinical use, a new method for radiochemical identity determination by HPLC analysis to complement standard TLC radiochemical purity measurement was developed. The results showed higher radiochemical yields when using MCX cartridge on the conventional module mAIO^®, while a PS-H+ cation exchanger was shown to be preferred for integration into the microfluidic cassette of iMiDEV™ module. In this study, the fully automated radiosynthesis of [⁶⁸Ga]Ga-citrate using different synthesizers demonstrated reliable and reproducible radiochemical yields. In order to demonstrate the applicability of [⁶⁸Ga]Ga-citrate, in vitro and in vivo studies were performed showing similar characteristics of the tracer obtained using macro- and microfluidic ways of production.

Translating a radiolabeled imaging agent to the clinic

Molecular Imaging is entering the most fruitful, exciting period in its history with many new agents under development, and several reaching the clinic in recent years. While it is unusual for just one laboratory to take an agent from initial discovery through to full clinical approval the steps along the way are important to understand for all interested participants even if one is not involved in the entire process. Here, we provide an overview of these processes beginning at discovery and preclinical validation of a new molecular imaging agent and using as an exemplar a low molecular weight disease-specific targeted positron emission tomography (PET) agent. Compared to standard drug development requirements, molecular imaging agents may benefit from a regulatory standpoint from their low mass administered doses, they nonetheless still need to go through a series of well-defined steps before they can be considered for Phase 1 human testing. After outlining the discovery and preclinical validation approaches, we will also discuss the nuances of Phase 1, Phase 2 and Phase 3 studies that may culminate in an FDA general use approval. Finally, some post-approval aspects of novel molecular imaging agents are considered.

Ac-EAZY! Towards GMP-Compliant Module Syntheses of 225Ac-Labeled Peptides for Clinical Application

The application of 225Ac (half-life T1/2 = 9.92 d) dramatically reduces the activity used for peptide receptor radionuclide therapy by a factor of 1000 in comparison to 90Y, 177Lu or 188Re while maintaining the therapeutic outcome. Additionally, the range of alpha particles of 225Ac and its daughter nuclides in tissue is much lower (47-85 μm for alpha energies Eα = 5.8-8.4 MeV), which results in a very precise dose deposition within the tumor. DOTA-conjugated commercially available peptides used for endoradiotherapy, which can readily be labeled with 177Lu or 90Y, can also accommodate 225Ac. The benefits are lower doses in normal tissue for the patient, dose reduction of the employees and environment and less shielding material. The low availability of 225Ac activity is preventing its application in clinical practice. Overcoming this barrier would open a broad field of 225Ac therapy. Independent which production pathway of 225Ac proves the most feasible, the use of automated synthesis and feasible and reproducible patient doses are needed. The Modular-Lab EAZY is one example of a GMP-compliant system, and the cassettes used for synthesis are small. Therefore, also the waste after the synthesis can be minimized. In this work, two different automated setups with different purification systems are presented. In its final configuration, three masterbatches were performed on the ML EAZY for DOTA-TATE and PSMA-I&T, respectively, fulfilling all quality criteria with final radiochemical yields of 80-90% for the 225Ac-labeled peptides.

Automated radiosynthesis of [68 Ga]Ga-PSMA-11 and [177 Lu]Lu-PSMA-617 on the iPHASE MultiSyn module for clinical applications

Prostate-specific membrane antigen (PSMA)-targeted imaging and therapy of prostate cancer using theranostic pairs is rapidly changing clinical practice. To facilitate clinical trials, fully automated procedures for the radiosyntheses of [68 Ga]Ga-PSMA-11 and [177 Lu]Lu-PSMA-617 were developed from commercially available precursors using the cassette based iPHASE MultiSyn module. Formulated and sterile radiopharmaceuticals were obtained in 76 ± 3% (n = 20) and 91 ± 4% (n = 15) radiochemical yields after 17 and 20 min, respectively. Radiochemical purity was always >95% and molar activities exceeded 792 ± 100 and 88 ± 6 GBq/μmol, respectively. Quality control showed conformity with all relevant release criteria and radiopharmaceuticals were used in the clinic.