Last reviewed by Dr. Dharmender Malik on 14 May 2026 · this article reflects the published primary literature and current clinical practice at FMRI Gurugram.
Introduction
Terbium-161 (Tb-161) is an emerging therapeutic radionuclide of significant research interest in the radioligand-therapy field. Its physical properties — a beta-emission profile similar to Lutetium-177 combined with additional short-range Auger and conversion electron emission — have generated substantial preclinical and early-clinical investigation as a potential next-generation alternative to Lu-177 for PSMA-targeted and somatostatin-receptor-targeted therapy. This handbook consolidates what is currently known about Tb-161 supply and indigenous production, the cycle protocols used in cohort experience to date, dosimetric considerations, and the practical answers to common questions. Tb-161 PSMA-617 and Tb-161 DOTATATE remain investigational — not FDA or EMA approved for any indication — and are delivered only under appropriate ethical-review-board oversight in research-protocol contexts.
Investigational status — Helsinki framework declaration
AI Overview · short answer
Terbium-161 (Tb-161) is a therapeutic radionuclide with a physical half-life of 6.9 days — similar to Lu-177's 6.65 days — that emits beta radiation with a mean tissue range of approximately 0.7 mm plus additional short-range Auger and conversion electrons with sub-cellular range (~10-100 nm)[1]. The theoretical advantage over Lu-177 is improved dose delivery to micrometastases and individual disease cells, with potentially preserved or improved efficacy at lower administered activity. Tb-161 PSMA-617 and Tb-161 DOTATATE remain investigational — neither has FDA or EMA approval — and are delivered only under research-protocol oversight aligned with the Helsinki framework[2]. Early-clinical evidence comes from the VIOLET phase 1/2 trial (Australia) and selected cohort experience in Germany and India[3].
Tb-161 radioligand therapy is currently investigational. Neither Tb-161 PSMA-617 nor Tb-161 DOTATATE has been approved by FDA, EMA, or DCGI for any cancer indication. Delivery of Tb-161 therapy is restricted to research-protocol contexts under appropriate ethical-review-board oversight, consistent with the World Medical Association Declaration of Helsinki principles for medical research involving human subjects[2].
This means in practice:
- Tb-161 cannot be offered as routine standard-of-care therapy.
- Patient access requires participation in an institutional review board (IRB)-approved clinical trial or, in limited settings, a compassionate-use or expanded-access pathway authorised by the relevant regulator.
- Standard-of-care alternatives — Lu-177 PSMA-617 for PSMA-positive mCRPC, Lu-177 DOTATATE for somatostatin-receptor-positive NETs — are FDA / EMA approved and remain the default options for eligible patients.
- Informed consent for Tb-161 therapy is comprehensive and explicit: investigational status, available alternatives, expected and unknown side-effect profile, the experimental nature of efficacy data.
This handbook describes what is currently understood about Tb-161 physics, cohort experience, and practical considerations — it does not advocate Tb-161 as a substitute for FDA / EMA approved therapy. Patients considering Tb-161 should engage in informed-consent discussion with their nuclear medicine and medical oncology teams.
Physical properties of Tb-161
Tb-161 is a beta-emitting therapeutic radionuclide with additional distinctive characteristics[1][4]:
| Property | Tb-161 value | Lu-177 (for comparison) |
|---|
| Physical half-life | 6.9 days | 6.65 days |
| Primary therapy emission | Beta minus | Beta minus |
| Beta endpoint energy | 593 keV maximum | 498 keV maximum |
| Mean beta tissue range | ~0.7 mm | ~0.7 mm |
| Additional emission | Auger + conversion electrons (sub-cellular range ~10-100 nm) | Minimal |
| Gamma emission (for SPECT) | 74.6 keV (10.2%), 48.9 keV (17%) | 113 keV (6%), 208 keV (10%) |
| Production route | Reactor irradiation of enriched Gadolinium-160 targets | Reactor or generator-derived |
The clinical interest in Tb-161 derives from the additional short-range Auger and conversion electron emission. Where Lu-177's beta radiation deposits dose with effective range of approximately 0.7 mm — appropriate for tumour cells in clusters — Tb-161's combined emission deposits beta dose at that same scale plus substantially higher dose at sub-cellular range, theoretically improving kill of single tumour cells and small disseminated micrometastases that would otherwise be sub-therapeutic targets[5].
Supply chain and indigenous production
Tb-161 production for medical use requires reactor irradiation of isotopically-enriched Gadolinium-160 (Gd-160) targets, followed by radiochemical separation of Tb-161 from the irradiated target material[6]. The supply chain has historically been constrained:
- International production centres include Paul Scherrer Institute (Switzerland), the Australian Nuclear Science and Technology Organisation (ANSTO), and selected European reactor facilities. Production at clinical-grade scale remains limited.
- Indian production — the Board of Radiation and Isotope Technology (BRIT), under the Department of Atomic Energy, has reported research-grade Tb-161 production capability using Dhruva and other research reactor facilities. Scale-up to routine clinical-grade supply is an ongoing development. The Indian Tb-161 supply ecosystem remains primarily research-protocol-supported at present[7].
- Radiochemical synthesis — Tb-161 is conjugated to DOTA-based chelator carriers using protocols broadly similar to Lu-177 DOTATATE / PSMA-617 synthesis, with adjustment for the specific radiochemistry of terbium ions.
- Quality control — radiochemical purity, radionuclide purity (separation from cogenerated Gd-159, Tb-160), and specific-activity targets — comparable in principle to Lu-177 production QC standards.
For an Indian centre delivering Tb-161 therapy under research protocol, the practical supply considerations include: BRIT or imported source availability, scheduling around the radionuclide half-life (similar logistics to Lu-177), and the regulatory pathway through DCGI / CDSCO for any IND-equivalent approval.
Treatment cycle protocol (research-protocol context)
The Tb-161 cycle protocol used in published cohort experience to date broadly mirrors the Lu-177 schedule for the corresponding targeting ligand[8]:
- Number of cycles — published Tb-161 PSMA-617 cohorts have used 2-6 cycles depending on protocol; the VIOLET phase 1/2 trial protocol uses up to 6 cycles. Tb-161 DOTATATE cohort experience is more limited and typically uses 2-4 cycles.
- Cycle interval — typically 6-8 weeks between cycles, similar to Lu-177 protocols.
- Administered activity per cycle — in published experience, in the range 5.5-7.4 GBq per cycle, with dose-escalation studies exploring the upper range. Lower activities relative to Lu-177 are theoretically supported by the additional Auger contribution but require trial-level validation.
- Renal protection (for DOTATATE protocols) — concurrent intravenous amino acid (lysine and arginine) infusion, identical to the Lu-177 DOTATATE renal-protection regimen.
- Pre-cycle workup — kidney function (eGFR), marrow counts, liver function, disease-specific biomarkers, baseline imaging (Ga-68 PSMA PET for PSMA-targeted; Ga-68 DOTATATE PET for SSTR-targeted).
- Post-administration imaging — Tb-161 SPECT/CT typically within 24-72 hours; the lower-energy gamma emissions (49 keV and 75 keV) provide acceptable post-therapy imaging quality for distribution confirmation.
- Inter-cycle monitoring — biochemistry and blood counts at intervals between cycles, with treatment-delay or activity-modification protocols for any developing toxicity.
These protocols are not yet standardised across centres in the way that Lu-177 PSMA-617 and Lu-177 DOTATATE protocols are now standardised through FDA / EMA labels and EANM procedure guidelines. Each Tb-161 cohort centre operates under its institutional research-protocol-specific procedure document.
Dosimetry considerations
Tb-161 dosimetry is an active area of clinical research, since the combined beta + Auger emission profile is not fully captured by standard Lu-177-derived dosimetric frameworks[9]:
- Whole-organ dose calculations — for tumour, kidney, marrow, and salivary gland — use modified MIRD frameworks that account for both the beta contribution (similar to Lu-177) and the additional Auger contribution.
- Sub-cellular dose considerations — the Auger and conversion electron contribution deposits substantial dose at nanometre scale around the radionuclide's intracellular location, which is not captured by conventional organ-level dosimetry. This is the key theoretical mechanism for improved micrometastasis kill.
- Comparative dosimetry vs Lu-177 — published preclinical work (Müller, Paul Scherrer Institute) suggests Tb-161 may deliver approximately 2-3× greater dose to small tumour cell clusters compared with Lu-177 at equivalent administered activity, due to the additional Auger contribution. Clinical-scale dosimetry studies in patient cohorts (e.g., VIOLET, Sydney) are confirming these dosimetric findings translate to patient-scale imaging.
- Salivary gland and kidney dosimetry — particular interest in whether the additional Auger contribution increases salivary-gland or renal toxicity compared with Lu-177 at equivalent administered activity. Early clinical evidence suggests the salivary-gland and renal dose profile is broadly similar to Lu-177, but cohort experience is limited and longer follow-up is required.
- Post-therapy imaging quantification — Tb-161's 49 keV and 75 keV gamma emissions enable post-therapy SPECT quantification, supporting individualised cycle-to-cycle dosimetric monitoring similar to Lu-177 protocols.
The dosimetric framework for Tb-161 is therefore evolving alongside the early-clinical experience, and direct comparisons with Lu-177 dosimetry require the same patient cohort and standardised methodology to be meaningful.
Early clinical evidence
Published clinical experience with Tb-161 therapy remains limited and is concentrated in a small number of pioneering research-protocol centres[10]:
- VIOLET phase 1/2 trial (Sydney, Australia) — first-in-human trial of Tb-161 PSMA-617 in metastatic castration-resistant prostate cancer post-Lu-177 PSMA-617 progression. Initial dose-escalation and expansion cohort findings have been presented at international meetings; primary publication is anticipated. The trial uses a Tb-161 PSMA-617 protocol with up to 6 cycles in selected patients with disease progression on prior Lu-177 therapy.
- Paul Scherrer Institute (Switzerland) cohort experience — preclinical and selected first-in-human experience with Tb-161 PSMA and Tb-161 DOTATATE under research-protocol oversight. Preclinical work has established the dosimetric advantage at micrometastasis level in mouse models.
- Heidelberg (Germany) — selected research-protocol experience with Tb-161 PSMA-617 in heavily pretreated patients with documented Lu-177 progression; case-series-level evidence.
- Indian research-protocol experience — emerging cohort experience under research-protocol oversight at selected tertiary centres. Indian published cohort data on Tb-161 PSMA-617 remains limited but is developing alongside the BRIT supply infrastructure.
It is important to be honest about what this evidence base does — and does not — currently support. The dosimetric advantage of Tb-161 over Lu-177 is well-established at preclinical level. Clinical efficacy data are emerging but limited; direct head-to-head randomised comparisons with Lu-177 are not yet available. Long-term outcome data, late-toxicity profiles, and optimal protocol parameters are still being defined. Tb-161 is at an early research-clinical stage of development.
Where Tb-161 might fit — current thinking
Within the constraints of investigational status and limited clinical evidence, current research-stage thinking about where Tb-161 might eventually fit includes[11]:
- Post-Lu-177 PSMA progression in mCRPC — the principal current research setting. For patients with PSMA-positive disease that has progressed on Lu-177 PSMA-617, the theoretical advantage of Tb-161's additional Auger contribution targets the micrometastatic disease component thought to limit Lu-177 efficacy. VIOLET trial setting.
- Disease with high micrometastatic component — theoretical advantage in disease patterns dominated by widespread small-volume disease (small nodal metastases, diffuse marrow involvement, small-volume bone disease).
- Equivalent setting to Lu-177 but at lower activity — research interest in whether Tb-161 can achieve Lu-177-equivalent tumour kill at lower administered activity, potentially reducing whole-body radiation exposure and toxicity. Would require randomised dose-comparison studies.
- NET indications — Tb-161 DOTATATE for somatostatin-receptor-positive NETs remains a much smaller clinical-evidence area than Tb-161 PSMA-617. Larger studies are still in earlier development.
None of these positions are yet evidence-confirmed at the level required for FDA / EMA approval, and all remain investigational. The honest framing is that Tb-161 is a promising research-stage modality that has not yet reached standard-of-care status, and that participation in well-conducted clinical trials remains the principal pathway to patient access.
Alternatives and decision context
For any patient considering Tb-161 therapy, the alternative pathways need to be explicit[12]:
- Lu-177 PSMA-617 (Pluvicto) — for PSMA-positive mCRPC, FDA-approved 2022, EMA-approved 2023, label expanded 2025; VISION + TheraP + PSMAfore evidence. The standard-of-care alternative for the principal Tb-161 PSMA-617 research setting.
- Lu-177 DOTATATE (Lutathera) — for somatostatin-receptor-positive GEP-NETs, FDA-approved 2018, EMA-approved 2017, label expanded 2024; NETTER-1 + NETTER-2 evidence. The standard-of-care alternative for the principal Tb-161 DOTATATE research setting.
- Cabazitaxel — for post-docetaxel mCRPC, TROPIC and CARD evidence; non-radioligand alternative.
- Ra-223 dichloride (Xofigo) — for symptomatic bone-metastatic CRPC, ALSYMPCA evidence; alpha-emitter alternative for bone-dominant disease.
- PARP inhibitors — for HRR-mutated mCRPC, PROfound + TRITON3 + TALAPRO-2 evidence; biomarker-targeted non-radioligand alternative.
- Best supportive care including hospice — for patients with limited life expectancy where additional disease-modifying therapy is not appropriate.
The decision to consider Tb-161 therapy is therefore not a decision between Tb-161 and "nothing" — it is a decision between investigational Tb-161 and the appropriate FDA / EMA approved alternative. That comparison framework needs to be explicit in informed-consent discussion.
Common patient questions — consolidated
Bringing together the questions that recurrently come up across patient and referring-clinician discussions about Tb-161:
- Is Tb-161 better than Lu-177? Preclinically, Tb-161 delivers approximately 2-3× greater dose to small tumour cell clusters at equivalent activity due to the additional Auger contribution. Clinically, that advantage is theoretical until randomised head-to-head clinical efficacy comparisons are available. The honest answer is: it has theoretical and preclinical advantages, with promising but limited early-clinical evidence; standard-of-care Lu-177 has substantial randomised-trial evidence base that Tb-161 does not yet have.
- Why isn't Tb-161 widely available? Three reasons: (1) the radionuclide is not yet FDA / EMA approved for any cancer indication; (2) supply infrastructure (production, distribution) is still limited compared with Lu-177; (3) clinical evidence is still at the early research-protocol stage.
- How is Tb-161 different from Lu-177? Almost identical half-life (6.9 vs 6.65 days), similar beta tissue range (~0.7 mm), similar targeting molecule attachment, similar cycle protocol structure. The principal difference is the additional Auger and conversion electron emission of Tb-161, which deposits substantial sub-cellular-range dose alongside the beta dose.
- Is Tb-161 a stronger radiation source than Lu-177? At organ-level dosimetry the two are broadly similar. At sub-cellular scale, Tb-161 deposits substantially more dose due to the Auger contribution. This is why the theoretical advantage is at micrometastasis level rather than at bulk-tumour level.
- Are the side effects different? Early clinical experience suggests a side-effect profile broadly similar to Lu-177 — fatigue, mild cytopenia, possible salivary gland and renal effects. Long-term cohort data are still being collected.
- How can a patient access Tb-161? Only through participation in an institutional review board (IRB)-approved clinical trial or, in limited settings, through compassionate-use or expanded-access pathway authorised by the relevant regulator. Standard outpatient access does not exist.
Regulatory framework
Tb-161 radioligand therapy operates under the same multi-layered regulatory framework as other nuclear medicine therapies, with additional requirements for investigational-status governance[13]:
- AERB (Atomic Energy Regulatory Board, India) — Safety Code AERB/RF-MED/SC-2 (Rev. 2) applies; specific licence conditions may be required for research-protocol use of investigational radionuclides.
- DCGI / CDSCO — clinical-trial authorisation for any Tb-161 study; investigational new drug (IND)-equivalent permissions; Good Manufacturing Practice for radiopharmaceutical preparation.
- Ethics committee (IRB) approval — institutional ethical-review-board approval mandatory for any patient delivery of investigational Tb-161 therapy, with explicit Helsinki-framework compliance documentation.
- BRIT (Board of Radiation and Isotope Technology) — indigenous Indian Tb-161 production for research use; supply chain coordination.
- Clinical trial registration — Clinical Trials Registry India (CTRI) or international equivalent (ClinicalTrials.gov) registration mandatory for trial-based delivery.
An international patient or referring clinician evaluating a Tb-161 trial pathway should confirm: trial registration in CTRI or ClinicalTrials.gov, IRB approval at the delivering institution, DCGI clinical-trial authorisation (in India), and the explicit informed-consent process. Tb-161 therapy delivered outside this regulatory framework is not appropriate.
The bottom line
- Terbium-161 (Tb-161) is an investigational therapeutic radionuclide; Tb-161 PSMA-617 and Tb-161 DOTATATE are NOT FDA or EMA approved for any indication[2].
- Physical properties: 6.9-day half-life, beta emission with ~0.7 mm tissue range plus additional Auger and conversion electrons with sub-cellular range (~10-100 nm)[1].
- The theoretical advantage over Lu-177 is improved dose delivery to single cells and micrometastases; preclinical work suggests approximately 2-3× greater dose to small tumour cell clusters at equivalent activity[5].
- Production is via reactor irradiation of enriched Gd-160 targets; international centres (PSI, ANSTO) and Indian BRIT facilities provide research-grade supply[6].
- Cycle protocol broadly mirrors Lu-177 — 2-6 cycles at 6-8 week intervals, activity 5.5-7.4 GBq, renal protection for DOTATATE protocols, post-therapy SPECT imaging[8].
- Clinical evidence is emerging from VIOLET (Sydney), Paul Scherrer Institute, Heidelberg, and Indian research-protocol cohorts; primary publications still anticipated[10].
- Patient access requires participation in an IRB-approved clinical trial; full Helsinki-framework informed consent is mandatory; standard-of-care Lu-177 remains the alternative for eligible patients[13].
Important
This article is a clinical handbook on investigational Terbium-161 radioligand therapy. Tb-161 PSMA-617 and Tb-161 DOTATATE are not FDA or EMA approved and are not available as routine standard-of-care therapy. Patient eligibility requires multidisciplinary tumour board review, institutional ethics committee approval, and clinical-trial registration. Standard-of-care alternatives are described and remain the default for eligible patients.
"Terbium-161 is a promising research-stage radionuclide with substantial theoretical and preclinical advantages over Lutetium-177 at the micrometastasis level. It is not yet FDA or EMA approved for any cancer indication. Patient access is restricted to research-protocol contexts with full Helsinki-framework compliance. The honest framing is: promising next-generation modality at an early-clinical stage, with standard-of-care Lu-177 remaining the default for eligible patients."
Dr. Ishita B. Sen, MD · Director & Chief, Nuclear Medicine, FMRI
Tb-161 research-protocol eligibility · FMRI
At FMRI Gurugram, Tb-161 therapy is delivered only under research-protocol oversight with institutional ethics committee approval, CTRI registration, and full Helsinki-framework informed consent. Standard-of-care alternatives — Lu-177 PSMA-617 for PSMA-positive mCRPC and Lu-177 DOTATATE for somatostatin-receptor-positive NETs — remain available for eligible patients.
Request consultation · WhatsApp +91 8800 988936
For patients & referring clinicians
Frequently asked questions
Q01
What is Terbium-161?
Terbium-161 (Tb-161) is a therapeutic radionuclide that emits beta radiation with mean tissue range of approximately 0.7 mm, plus additional short-range Auger and conversion electrons with sub-cellular range. Its physical half-life is 6.9 days, similar to Lu-177's 6.65 days. It is being investigated for radioligand therapy of PSMA-positive prostate cancer (Tb-161 PSMA-617) and somatostatin-receptor-positive neuroendocrine tumours (Tb-161 DOTATATE). It is currently investigational and not FDA or EMA approved [1][2].
Q02
How is Tb-161 different from Lu-177?
Tb-161 and Lu-177 have very similar physical half-lives (6.9 vs 6.65 days) and similar mean beta tissue range (~0.7 mm). The principal physical difference is that Tb-161 also emits short-range Auger and conversion electrons that deposit substantial dose at sub-cellular range (~10-100 nm). The clinical implication: Tb-161 theoretically delivers approximately 2-3× more dose to small tumour cell clusters and individual disease cells at equivalent administered activity. The targeting molecule and overall therapy structure (DOTA chelator, peptide ligand, multi-cycle protocol) are similar. Lu-177 has substantial randomised-trial evidence and FDA/EMA approval; Tb-161 has emerging early-clinical evidence and investigational status [1][5].
Q03
Is Tb-161 approved by the FDA or EMA?
No. Tb-161 PSMA-617 and Tb-161 DOTATATE remain investigational and are not currently approved by the FDA, EMA, DCGI, or any other major regulator for any cancer indication. Delivery is restricted to research-protocol contexts under appropriate ethical-review-board oversight. Standard-of-care Lu-177 PSMA-617 (FDA 2022, EMA 2023) and Lu-177 DOTATATE (FDA 2018, EMA 2017) are the approved alternatives for the principal Tb-161 research indications [2].
Q04
Where is Tb-161 produced?
Tb-161 is produced by reactor irradiation of enriched Gadolinium-160 (Gd-160) targets, followed by radiochemical separation. International production centres include Paul Scherrer Institute (Switzerland), ANSTO (Australia), and selected European reactor facilities. In India, the Board of Radiation and Isotope Technology (BRIT), under the Department of Atomic Energy, has reported research-grade production capability. Scale-up to routine clinical-grade supply is an ongoing development [6][7].
Q05
What does a Tb-161 cycle protocol look like?
Tb-161 cycle protocols broadly mirror Lu-177 schedules: 2-6 cycles depending on protocol, 6-8 week intervals between cycles, administered activity in the range 5.5-7.4 GBq per cycle, concurrent intravenous amino acid renal protection (for DOTATATE protocols), pre-cycle workup (kidney function, marrow counts, biochemistry, baseline imaging), post-administration Tb-161 SPECT/CT imaging at 24-72 hours, and inter-cycle monitoring. Specific parameters vary by trial protocol and are not yet standardised the way Lu-177 protocols are standardised through FDA/EMA labels and EANM guidelines [8].
Q06
How is dosimetry done for Tb-161?
Tb-161 dosimetry uses modified MIRD frameworks that account for both the beta contribution (similar to Lu-177) and the additional Auger contribution. Whole-organ dose calculations (tumour, kidney, marrow, salivary gland) are performed similarly to Lu-177. Sub-cellular dose considerations — the Auger and conversion electron contribution at nanometre scale — are an active area of research methodology. Post-therapy Tb-161 SPECT (using the 49 keV and 75 keV gamma emissions) enables individualised cycle-to-cycle quantification similar to Lu-177 [9].
Q07
What is the VIOLET trial?
VIOLET is the principal first-in-human phase 1/2 clinical trial of Tb-161 PSMA-617 for metastatic castration-resistant prostate cancer post-Lu-177 PSMA-617 progression, conducted in Sydney, Australia, under research-protocol oversight. The trial uses a Tb-161 PSMA-617 protocol with up to 6 cycles in selected patients with disease progression on prior Lu-177 therapy. Initial findings have been presented at international conferences; primary publication is anticipated. VIOLET is the principal current source of clinical-scale Tb-161 PSMA-617 efficacy and safety data [10].
Q08
What are the side effects of Tb-161?
Early clinical experience suggests a side-effect profile broadly similar to Lu-177 — fatigue, mild cytopenia (anaemia, thrombocytopenia, lymphopenia), possible salivary gland effects and renal effects. Long-term cohort data are still being collected. Whether the additional Auger contribution increases or alters specific toxicity patterns compared with Lu-177 is an active research question; current evidence does not show meaningfully different toxicity, but follow-up duration is limited and patient numbers are small. Standard radiation-safety precautions apply [3][9].
Q09
Can I get Tb-161 therapy at FMRI?
Tb-161 therapy at FMRI is delivered only under research-protocol oversight with institutional ethics committee approval, CTRI registration, DCGI clinical-trial authorisation, and full Helsinki-framework informed consent. Standard-of-care alternatives — Lu-177 PSMA-617 for PSMA-positive mCRPC and Lu-177 DOTATATE for somatostatin-receptor-positive NETs — are FDA and EMA approved and remain the default options for eligible patients. WhatsApp +91 8800 988936 to begin a confidential discussion about eligibility and available pathways.
Q10
How does Tb-161 compare with Ac-225 alpha therapy?
Tb-161 and Ac-225 are both research-stage alternatives to Lu-177 with different physical mechanisms. Tb-161 is a beta emitter (similar to Lu-177) with additional Auger contribution; mean tissue range ~0.7 mm; theoretical advantage at micrometastasis level. Ac-225 is an alpha emitter with much shorter range (40-100 micrometres) and substantially higher linear energy transfer per emission; theoretical advantage at single-cell kill but also higher toxicity profile concerns (xerostomia in particular). Both remain investigational; both are studied principally in Lu-177-progression mCRPC. Direct comparative trials have not been conducted [11].
Q11
How can a patient access Tb-161 therapy?
Only through participation in an institutional review board (IRB)-approved clinical trial or, in limited settings, through compassionate-use or expanded-access pathway authorised by the relevant regulator (DCGI / CDSCO in India, FDA in the US, EMA in Europe). Standard outpatient access to Tb-161 therapy does not exist. Eligibility for available trials requires multidisciplinary tumour board review and explicit Helsinki-framework informed consent including discussion of approved alternatives [2][13].
Q12
What is the regulatory framework for Tb-161 in India?
Tb-161 in India operates under: AERB Safety Code AERB/RF-MED/SC-2 (Rev. 2) for nuclear medicine facilities; DCGI / CDSCO clinical-trial authorisation under the Drugs and Cosmetics Act for any patient-delivery study; institutional ethics committee (IRB) approval; Clinical Trials Registry India (CTRI) registration; BRIT or imported radionuclide supply with appropriate import permissions. Tb-161 therapy delivered outside this regulatory framework is not appropriate. The framework is aligned with international research-protocol standards including the World Medical Association Helsinki Declaration [13].
Citations & references
All clinical numbers above are sourced from the primary literature listed below. Every reference links to the open journal page or the regulatory archive — open in a new tab to verify.
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212Pb as a clinical therapeutic; getting the lead in!
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View source ↗[30] Paul Scherrer Institute (PSI), Centre for Radiopharmaceutical Sciences. Research programmes on terbium-161 and next-generation theranostic radionuclides.
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About the Author
Dr. Ishita B. Sen
MBBS · MD (Nuclear Medicine) · DNB · Post-doctoral Fellowship, Memorial Sloan Kettering Cancer Center, New York
Director and Chief of Nuclear Medicine at Fortis Memorial Research Institute. Co-founder of Theranostic Physicians Private Limited (TPPL). Two decades of clinical practice in PSMA imaging and PSMA-directed radioligand therapy, with one of the largest Indian institutional experiences in Lu-PSMA.