Terbium-161 Therapy: Frequently Asked Questions

1. Is the supply of Terbium-161 stable?

Yes. At Fortis Memorial Research Institute (FMRI) in Gurugram, we have a steady supply of Terbium-161, sourced from TerThera, a leading global producer based in the Netherlands. We receive shipments approximately twice a month, ensuring that therapy scheduling for patients is consistent and predictable.

Source: https://www.advancingnuclearmedicine.com/news/nrg-and-terthera-sign-irradiation-agreement-to-ensure-the-continuous-supply-of-terbium-161

2. How is Terbium-161 therapy administered?

The administration protocol for Tb-161 is very similar to Lutetium-177 therapy. After confirming eligibility through a PSMA PET or DOTATOC scan, patients are admitted for a daycare or short one-night admission. A cannula is inserted, hydration is provided, and amino acids may be given to protect the kidneys. The Tb-161 labeled ligand is then injected intravenously via a short infusion.

 3. What is the role of dosimetry scans with Terbium-161?

Tb-161 emits gamma radiation, which enables post-therapy imaging. After therapy, dosimetry scans are performed typically on the same day, the next day, and again after 3–4 days. These scans help calculate the radiation absorbed by the tumor, kidneys, and bone marrow, allowing us to adjust subsequent therapy cycles safely.

 4. How many cycles of Tb-161 therapy are needed?

Patients usually require between 4 to 6 cycles of Tb-161 therapy. Each cycle is typically spaced 8 to 12 weeks apart, depending on dosimetry findings, patient tolerance, and tumor response.

5. What are the benefits of Tb-161 over Lutetium-177?

Tb-161 offers several important advantages:

•  It delivers ~40% more radiation dose to tumor cells per molecule compared to Lu-177.
•  It emits Auger and conversion electrons in addition to beta particles, leading to highly localized cell kill.
•  Because more radiation is concentrated in the tumor per molecule, lower total radioactivity can be administered, reducing potential toxicity to organs like the kidneys and bone marrow.

Sources:

https://jnm.snmjournals.org/content/65/supplement_2/2430

https://ejnmmiphys.springeropen.com/articles/10.1186/s40658-023-00589-w

6. Can Tb-161 help patients who did not respond to Lu-177?

While there is no definitive clinical data yet proving that Tb-161 improves outcomes in patients who progressed on Lu-177, the theoretical advantage exists. Because Tb-161 is better at killing single residual tumor cells (which often cause relapse), it may offer benefits even in those who had suboptimal response to Lutetium therapy.

7. What is the VIOLET study and what does it tell us about Tb-161?

The VIOLET study is a Phase I/II clinical trial led by Prof. Michael Hofman at the Peter MacCallum Cancer Centre, Melbourne, Australia. It is comparing Tb-161 PSMA therapy head-to-head against Lu-177 PSMA therapy in metastatic castration-resistant prostate cancer (mCRPC) patients. Early results suggest Tb-161 may offer improved efficacy without increasing toxicity.

Learn more:

https://jnm.snmjournals.org/content/65/8/1231

8. Could Terbium-161 replace Lutetium-177 in the future?

Initial evidence, including results from the VIOLET study, suggests that Tb-161 may outperform Lu-177, especially in terms of tumor control and reducing recurrence risk. In the future, Tb-161 could become the preferred first-line beta emitter for targeted radioligand therapy in various cancers.

9. How can I consult for Terbium-161 therapy at FMRI?

Patients and caregivers are encouraged to send their medical history, imaging (like PSMA PET or DOTATOC scans), and previous treatment records to Dr. Ishita B. Sen for a quick expert opinion.

Please email your documents to: info@nuclearmedicinetherapy.in

Timely access to targeted therapy can make all the difference.

At FMRI, we ensure both expertise and availability to help you take confident next

Also Read