DOTATOC

DOTA-Tyr3-octreotide, DOTA-TOC, edotreotide; Ga-68 DOTATOC = gallium Ga 68 edotreotide (SomaKit TOC kit in the EU); Lu-177 DOTATOC = 177Lu-edotreotide, ITM-11; Y-90 DOTATOC (older therapy)

Oncology & imaging

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Note on this profile. Ga-68 DOTATOC is an approved diagnostic radiopharmaceutical in the US and EU. Lu-177 DOTATOC (edotreotide) is investigational with a completed Phase 3 trial. Both are hospital-only agents; there is no community or self-directed use.

1What it is

DOTATOC is the older sibling of DOTATATE (#201). It is octreotide with a tyrosine swapped in at position 3 and a DOTA chelator attached, developed in Basel in the 1990s so that octreotide could carry a therapeutic metal rather than just the indium-111 used for scanning. Y-90 DOTATOC was the first widely used peptide receptor radionuclide therapy (PRRT) and treated thousands of patients in Europe in the 2000s before Lu-177 DOTATATE's cleaner kidney profile and randomised data made it the standard. Ga-68 DOTATOC was the first Ga-68 somatostatin PET tracer and remains the approved Ga-68 kit in the EU.

Chemically the difference from DOTATATE is a single C-terminal residue (threoninol in DOTATOC vs threonine in DOTATATE). DOTATATE binds SSTR2 somewhat more tightly ; in patients the imaging performance of the two is near-identical.

2How it's thought to work

Identical in principle to DOTATATE: receptor-mediated binding and internalisation into SSTR2-expressing cells, with imaging or irradiation by the attached isotope. Y-90's higher-energy beta particles travel further (up to ~11 mm), which helps in larger tumours but deposits more dose in the kidney; Lu-177's shorter range (~2 mm) suits smaller lesions and spares surrounding tissue. Edotreotide shows slightly lower kidney retention per unit activity than octreotate in some dosimetry studies, which is one argument made for it in therapy.

The same targeting idea with a Tyr3-octreotide core. Bound to SSTR2 and internalised, it either maps the disease with gallium-68 or irradiates it from within with lutetium-177 or yttrium-90.Schematic — not to scale

3What the research shows

Lu-177 edotreotide vs everolimus in GEP-NETs

COMPETE, a Phase 3 trial (207 patients on Lu-177 edotreotide, 102 on everolimus) in grade 1–2 progressive SSTR-positive GEP-NETs, reported median PFS of 23.9 vs 14.1 months by central review (HR 0.67) in results presented in 2025 (conference presentation 2025; full publication †). This is the first randomised comparison of PRRT with a targeted drug rather than with high-dose somatostatin analogue. A sister trial, COMPOSE, is testing it against chemotherapy or everolimus in higher-grade tumours †.

Graded B (large uncontrolled series)

Y-90 DOTATOC

A single-centre Phase 2 of 1,109 patients reported morphological response in 34% and median survival of ~95 months in responders, with severe permanent kidney toxicity in 9% (Imhof 2011, J Clin Oncol). Uncontrolled, but it established PRRT as a treatment. [4]

Lu-177 DOTATOC retrospective series

A retrospective analysis of 56 patients treated with Lu-177 DOTATOC reported disease control in the majority with modest haematological toxicity (Baum 2016, Oncotarget). [5]

Graded A/B

Ga-68 DOTATOC PET for NET detection

The first-in-human and subsequent comparisons showed sensitivity around 90–97% and superiority over In-111 pentetreotide SPECT (Hofmann 2001, Eur J Nucl Med; Gabriel 2007, J Nucl Med — 84 patients prospective). Head-to-head with Ga-68 DOTATATE, lesion detection is comparable (Poeppel 2011, J Nucl Med). [1][2][3]

Meningioma, paraganglioma, pheochromocytoma imaging

Prospective and retrospective series support Ga-68 DOTATOC PET for radiotherapy planning in meningioma and for extra-adrenal paraganglioma detection; these are off-label or guideline-supported rather than labelled uses.

4Reported side effects and interactions

Literature-reported

Literature (therapy). Y-90 DOTATOC carried meaningful kidney toxicity even with amino-acid protection, which is why it is now rarely used. Lu-177 edotreotide in COMPETE: haematological toxicity (anaemia, thrombocytopenia, lymphopenia) and nausea were the common events; renal toxicity rates reported as low; full safety tables pending publication †. Delayed myeloid neoplasms are a class risk for all PRRT.

Literature (Ga-68 DOTATOC). no clinically significant adverse reactions reported in the pivotal data; rare mild nausea or flushing.

Community-reported

Community use. essentially none documented.

Theoretical. same gonadal and fertility considerations as DOTATATE.

Interactions. somatostatin analogues compete for binding and are withheld before imaging and treatment; corticosteroids may lower receptor expression.

Markers researchers commonly monitor

Same framework as DOTATATE, drawn from PRRT protocols:

Marker	Why it's watched
CBC before each cycle and at intervals for years afterwards	marrow toxicity and delayed MDS/leukaemia.
Creatinine, eGFR, urinalysis	kidney is the critical organ, historically the limiting one for Y-90 DOTATOC.
Liver function tests	hepatic metastasis burden and radiation hepatitis risk.
Chromogranin A, 5-HIAA, tumour-specific hormones	biochemical response.
Ga-68 somatostatin PET	confirms eligibility and tracks response.
Dosimetry imaging after each cycle	Lu-177's gamma emission lets teams estimate kidney and marrow absorbed dose; increasingly used to individualise cycles.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Not applicable to individuals. SomaKit TOC is a kit labelled with Ga-68 from a generator in a hospital radiopharmacy; the US product is prepared similarly under site-specific procedures. Therapeutic Lu-177 edotreotide is supplied as an investigational radiolabelled solution. No calculator link is provided for this compound.

6Commonly studied alongside

DOTATATE (#201) as the direct comparator; octreotide (#124) and lanreotide between cycles; pentetreotide (#204); everolimus as the Phase 3 comparator; satoreotide (#205).

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Ga-68 DOTATOC FDA-approved August 2019 (NDA held by an academic centre) for PET localisation of SSTR-positive NETs in adults and children. Lu-177 edotreotide not approved; Phase 3 complete, submission timing †
European Union	SomaKit TOC (Ga-68 edotreotide kit) EMA-authorised December 2016. Lu-177 edotreotide not authorised (investigational)
United Kingdom	SomaKit TOC licensed via MHRA †; Lu-177 edotreotide investigational
Australia	Ga-68 DOTATOC used under hospital production in some centres; branded kit registration †. Lu-177 edotreotide investigational
South Africa	Not registered as a branded product; academic-centre use under section 21 access †
Sport (WADA)	Not listed

8Open questions

Whether Lu-177 edotreotide and Lu-177 DOTATATE differ in efficacy or kidney safety in a head-to-head trial; none exists.
Optimal cycle number and interval; whether dosimetry-guided dosing improves outcomes.
Role of PRRT earlier in the disease course and in combination with chemotherapy or targeted agents.

9References

1Hofmann M et al. (2001). Biokinetics and imaging with the somatostatin receptor PET radioligand 68Ga-DOTATOC: preliminary data. Eur J Nucl Med. DOI
2Gabriel M et al. (2007). 68Ga-DOTA-Tyr3-octreotide PET in neuroendocrine tumors: comparison with somatostatin receptor scintigraphy and CT. J Nucl Med. PubMed · DOI
3Poeppel TD et al. (2011). 68Ga-DOTATOC versus 68Ga-DOTATATE PET/CT in functional imaging of neuroendocrine tumors. J Nucl Med. PubMed · DOI
4Imhof A et al. (2011). Response, survival, and long-term toxicity after therapy with the radiolabeled somatostatin analogue [90Y-DOTA]-TOC in metastasized neuroendocrine cancers. J Clin Oncol. PubMed · DOI
5Baum RP et al. (2016). [177Lu-DOTA]0-D-Phe1-Tyr3-octreotide (177Lu-DOTATOC) for peptide receptor radiotherapy in patients with advanced neuroendocrine tumours: a phase-II study. Oncotarget. DOI
6COMPETE investigators (2025). Phase 3 trial of 177Lu-edotreotide versus everolimus in SSTR-positive GEP-NETs (NCT03049189); conference presentation 2025 [verify full publication]. PubMed
7EMA. SomaKit TOC: EPAR product information. FDA. Gallium Ga 68 DOTATOC injection prescribing information. PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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Self-reported side effects Phase 2

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11Page history

31 Oct 2026Profile published — awaiting medical review

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