3PC-013 Radiopharmaceutical single-vial cold kit formulation of FAPI-04, an experimental vector for gallium-68 PET imaging in oncology
Bibliographic record
Abstract
Background and Importance Targeting the tumour microenvironment recently gained interest in oncology, as evidenced by the use of fibroblasts activation protein inhibitors (FAPI) for cancer-associated fibroblasts imaging. Among these derivatives, FAPI-04 radiolabeled with gallium-68 emerged as a promising PET diagnostic agent. To date, [68Ga] Ga-FAPI-04 is considered an experimental radiopharmaceutical, with a tedious and intricate radiolabeling process. Thus, the development of a single-vial cold kit (SVCK) formulation of FAPI-04 to simplify the preparation of [68Ga] Ga-FAPI-04 would be of particular interest. Aim and Objectives Various parameters involved in the formulation of FAPI-04 as a SVCK were investigated. Then, optimal conditions for successful radiolabeling of [68Ga] Ga-FAPI-04 were identified. Material and Methods Kit vials were conditioned to contain several bulk agents (five tested), buffers (six tested), anti-radiolysis compound (three tested) and FAPI-04. Mixtures were solubilised in water for injection and then lyophilised. The influence of each component on the radiolabeling process was studied, as well as the amount of vector (30, 45 or 60 µg). [68Ga] GaCl3 was eluted from a GalliAD® generator directly into the kit vials, subsequently heated for 10 minutes at 97°C. Radiochemical purity (RCP) of each reaction was assessed by radio-TLC and radio- HPLC. The pH was checked by pH strips during the kit’s conditioning and after each reaction, aiming at an optimal value of 3.4 (ideal for 68Ga radiolabeling). Results Mannitol (50 mg) was the bulk agent with the best appearance after freeze-drying and was retained in subsequent assays. As expected, the pH of the reaction medium was critical to the success of radiolabeling. HEPES buffer 0.3 M pH 4 allowed RCP of 83.3% by TLC and 78.9% by HPLC, compared with extremely poor results obtained with the five other buffers. Anti-radiolysis agents showed a moderate improvement in RCP (~10% increase with ascorbic acid) which persisted over a period of 4 hours, confirming radiocomplex stability. Using 45 µg FAPI-04 instead of 30 µg in the reaction slightly increased RCP (>96% in TLC, >91% in HPLC). Conclusion and Relevance The importance of carefully selecting the ingredients of a radiopharmaceutical SVCK was demonstrated, resulting in excellent RCP values for [68Ga] Ga-FAPI-04. A terminal purification step would remove HEPES buffer to comply with European Pharmacopoeia requirements. References and/or Acknowledgements Conflict of Interest No conflict of interest.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".