Below is my speculation of 18F being used to improve TLX400. I...

Below is my speculation of 18F being used to improve TLX400. I have often wondered what commercial reason for not disclosing the Isotope.

Anyway i asked AI the question............beware of hallucinations and always DYOR

How 18F-AlF Could Support TLX400 in Bladder Cancer

1. What is TLX400?

• TLX400 is Telix's investigational antibody targeting CDx (carbonic anhydrase IX, CAIX), which is overexpressed in bladder cancer, renal cell carcinoma, and some hypoxic tumors.

• Originally developed with Zirconium-89 (⁸⁹Zr) for PET imaging due to its long half-life (suitable for antibodies), but this has limitations (e.g., delayed imaging, higher radiation burden).

2. How 18F-AlF Could Improve TLX400

	Feature	⁸⁹Zr-TLX400	Possible [¹⁸F]AlF-TLX400
1	Isotope Half-Life	~78 hours	~110 minutes
2	Radiation Burden	Higher	Lower
3	Imaging Timeframe	3–7 days post-injection	Same-day imaging possible
4	Manufacturing	Central, expensive	Flexible: cyclotron + kit format
5	Patient Throughput	Slower	Faster, more scalable

18F-AlF could allow for:

• Faster imaging post-injection, possibly within 2–6 hours instead of days

• Lower radiation dose, improving safety—especially relevant in repeated monitoring

• Wider accessibility, enabling broader clinical adoption of TLX400-based diagnostics

3. Implications for Bladder Cancer

• Earlier detection of superficial or muscle-invasive disease

• Improved ability to map multifocal tumors or occult nodal spread

• Potential synergy with robot-assisted cystectomy or radiotherapy planning

Future Outlook

• A reformulated [¹⁸F]AlF-labeled version of TLX400 would need:

  • Development of a suitable chelator for stable AlF-antibody conjugation

  • Preclinical and clinical validation (biodistribution, tumor uptake, clearance)

• Could eventually support theranostic pairing (diagnostic [18F] + therapeutic 177Lu or 225Ac)