Position statement on radiopharmaceutical production for clinical trials

Clinical-grade N-(4-[18F]fluorobenzoyl)-interleukin-2 for PET imaging of activated T-cells in humans

Background

Molecular imaging of immune cells might be a potential tool for response prediction, treatment evaluation and patient selection in inflammatory diseases as well as oncology. Targeting interleukin-2 (IL2) receptors on activated T-cells using positron emission tomography (PET) with N-(4-[¹⁸F]fluorobenzoyl)-interleukin-2 ([¹⁸F]FB-IL2) could be such a strategy. This paper describes the challenging translation of the partly manual labeling of [¹⁸F]FB-IL2 for preclinical studies into an automated procedure following Good Manufacturing Practices (GMP), resulting in a radiopharmaceutical suitable for clinical use.

Methods

The preclinical synthesis of [¹⁸F]FB-IL2 was the starting point for translation to a clinical production method. To overcome several challenges, major adaptations in the production process were executed. The final analytical methods and production method were validated and documented. All data with regards to the quality and safety of the final drug product were documented in an investigational medicinal product dossier.

Results

Restrictions in the [¹⁸F]FB-IL2 production were imposed by hardware configuration of the automated synthesis equipment and by use of disposable cassettes. Critical steps in the [¹⁸F]FB-IL2 production comprised the purification method, stability of recombinant human IL2 and the final formulation. With the GMP compliant production method, [¹⁸F]FB-IL2 could reliably be produced with consistent quality complying to all specifications.

Conclusions

To enable the use of [¹⁸F]FB-IL2 in clinical studies, a fully automated GMP compliant production process was developed. [¹⁸F]FB-IL2 is now produced consistently for use in clinical studies.

Electronic supplementary material

The online version of this article (10.1186/s41181-019-0062-7) contains supplementary material, which is available to authorized users.

Fully Automated 89Zr Labeling and Purification of Antibodies

Dozens of monoclonal antibodies (mAbs) have been approved for clinical use, and hundreds more are under development. To support these developments and facilitate a personalized medicine approach, PET imaging and quantification of mAbs, after chelation with desferrioxamine B (DFO) and radiolabeling with ⁸⁹Zr, has become attractive. Also, the use of ⁸⁹Zr-mAbs in preclinical and clinical studies is expanding rapidly. Despite these rapid developments, ⁸⁹Zr radiolabeling is still performed manually. Therefore, we aimed to develop a simple, fully automated, good-manufacturing-practice (GMP)-compliant production procedure for the ⁸⁹Zr labeling of mAbs. Such procedures should increase the robustness and capacity of ⁸⁹Zr-mAb production while minimizing the radiation dose to the operator. Here, the procedures for fully automated ⁸⁹Zr-mAb production are described and applied to produce batches of ⁸⁹Zr-DFO-N-suc-cetuximab and ⁸⁹Zr-DFO-N-suc-rituximab suitable for clinical use. Both products had to meet the GMP-compliant quality standards with respect to yield, radiochemical purity, protein integrity, antigen binding, sterility, and endotoxin levels. Methods: Automated ⁸⁹Zr labeling of mAbs was developed on a Scintomics GRP 2V module and comprised the following steps: reagent transfer to the ⁸⁹Zr-containing reaction vial, mixing of the reagents followed by a 60-min reaction at room temperature to obtain optimal radiolabeling yields, and product purification using a PD-10 desalting column. Results: Radiochemical yields of ⁸⁹Zr-DFO-N-suc-cetuximab and ⁸⁹Zr-DFO-N-suc-rituximab were all more than 90% according to instant thin-layer chromatography. Isolated yields were 74.6% ± 2.0% and 62.6% ± 3.0% for ⁸⁹Zr-DFO-N-suc-cetuximab and ⁸⁹Zr-DFO-N-suc-rituximab, respectively, which are similar to isolated yields obtained using GMP protocols for manual ⁸⁹Zr labeling of mAbs. To meet the GMP-compliant quality standards, only the radiochemically pure fractions were collected from PD-10, resulting in a lower isolated yield than the radiochemical yield according to instant thin-layer chromatography. The radiochemical purity and protein integrity were more than 95% for both products, and the antigen binding was 95.6% ± 0.6% and 87.1% ± 2.2% for ⁸⁹Zr-DFO-N-suc-cetuximab and ⁸⁹Zr-DFO-N-suc-rituximab, respectively. The products were sterile, and the endotoxin levels were within acceptable limits, allowing future clinical production using this procedure. Conclusion: Procedures for fully automated GMP-compliant production of ⁸⁹Zr-mAbs were developed on a commercially available synthesis module, which also allows the GMP production of other radiolabeled mAbs.

Harmonization of United States, European Union and Canadian First-in-Human Regulatory Requirements for Radiopharmaceuticals-Is This Possible?

In recent years, several new radiotracers and radionuclide therapies have been developed. There is a renaissance in nuclear medicine and molecular imaging today, for example, in terms of the ability to image and treat neuroendocrine and prostate malignancies. In order to be able to bring a new drug product from bench to bedside and assist patients, while also ensuring patient safety, stringent regulations must be met. However, differences in regulatory requirements, often based on jurisdictional politics rather than scientific evidence, can hinder global co-operation, increase expense, and slow progress. In an effort to rise above these differences, nuclear medicine advocacy organizations, regulators, and international agencies have begun to identify commonalities in the regulations to achieve harmonization. Indeed, a more streamlined approach to radiopharmaceutical drug development across jurisdictions could be achieved through establishing harmonized requirements for pre-clinical studies and manufacturing standards. This paper provides an educational overview of the regulatory and submission requirements governing investigational radiopharmaceuticals for first-in-human radiopharmaceuticals across the European and North American continents. It is hoped that through ongoing collaboration, regulatory reform and harmonization can become a reality and speed access to the most up-to-date evidence-based patient care for all.