US Patent 5,776,894: Claim Scope, Expiration, Orange Book Status, and Somatostatin Radiopharmaceutical Patent Landscape

US Patent 5,776,894 covers radiolabeled somatostatin peptides in which a chelating group is attached to the peptide's N-terminal amino group, together with radionuclide complexes, pharmaceutical compositions, and treatment of somatostatin-receptor-positive tumors. The patent issued July 7, 1998 and its enforceable term expired in 2015 under the pre-URAA 17-year-from-grant regime. It does not create a current blocking right against OctreoScan, Lutathera, generic radiolabeled somatostatin peptides, or later peptide-radionuclide products.[1]

What does US Patent 5,776,894 protect?

The patent protects a platform technology rather than one narrowly defined commercial product. Its independent claims reach four principal subject-matter categories:

Claim category	Claims	Protected subject matter
Chelator-linked peptide	1	Somatostatin peptide with a physiologically acceptable chelating group linked directly or indirectly to the N-terminal amino group
Structural peptide and chelator species	2-10	Spacer, amide or thiourea linkage; defined somatostatin analogs; specified chelators including DTPA, DOTA, EDTA, TETA and related agents
Radiometal complexes	11-17	Peptides complexed with detectable elements, including gamma-, beta-, alpha- and positron-emitting radionuclides
Pharmaceutical and therapeutic use	18-19	Pharmaceutical compositions and treatment of somatostatin-receptor-positive tumors using alpha- or beta-emitting complexes

Claim 1 is the broadest composition claim. It requires:

A somatostatin peptide.
A physiologically acceptable chelating group.
A detectable element-compatible chelator.
Covalent attachment to the N-terminal amino group, directly or through an intervening group.

The claim does not require a particular radionuclide, chelator, peptide sequence, tumor type, dosage, imaging indication or administration route.

How broad is claim 1 of US 5,776,894?

Claim 1 has potentially broad literal scope because it does not limit the invention to octreotide, DTPA, DOTA, indium-111 or a particular peptide sequence. The claim covers both unlabeled chelator-peptide conjugates and their pharmaceutically acceptable salts.

The principal limiting element is the location of attachment. The chelating group must be covalently linked to the N-terminal amino group. A compound linked through a lysine side chain, cysteine thiol, internal amine or a noncovalent association would fall outside the literal wording of claim 1 unless another claim or an equivalents theory applied.

Claims 2 through 4 clarify possible attachment architectures:

Claim 2 covers an indirect attachment through a spacer or bridging group.
Claim 3 covers an amide bond.
Claim 4 covers a thiourea bond.

These claims do not materially displace claim 1's broader direct-or-indirect formulation. They provide narrower fallback positions and may assist claim construction if the scope of “indirectly” is disputed.

What somatostatin peptides are covered by claims 5 through 10?

Claims 5 through 10 define a large family of cyclic somatostatin analogs using variable residues and substituents. The structural limitations include:

An N-terminal acyl or amino-acid-derived group designated A.
Phe or beta-naphthylalanine at B.
L- or D-tryptophan at C, with optional N-methylation and ring substitution.
Lysine or substituted aminocyclohexylalanine/glycine at D.
Thr, Ser, Val, Phe, Ile or selected non-natural amino acids at E.
A variable C-terminal group designated G.
Specified L/D stereochemical configurations.
Optional alkylation, esterification and side-chain substitutions.

Claim 6 narrows the peptide to a specific structure reproduced in the patent drawings. Claim 10 narrows it to a further identified compound. Because the supplied text does not include the chemical structures represented by the image placeholders, the exact identity of the compounds in claims 6 and 10 cannot be determined from the text alone.

The sequence and stereochemistry limitations are important. A later product with a different residue at a defined position, including a Tyr substitution, a changed disulfide-loop architecture or a different C-terminal alcohol/acid group, may avoid claims 5-10 even if it retains somatostatin-receptor binding.

What chelators and radionuclides are covered?

Claim 7 covers several chelator classes, including:

Iminodicarboxylic compounds.
Polyaminopolycarboxylic compounds.
Macrocyclic amines.
Bis-aminothiol derivatives.
Dithiasemicarbazones.
Propylene amine oximes.
Diamide dimercaptides.
Porphyrins.
Deferoxamine-derived groups.

Claim 8 expressly identifies EDTA, DTPA, EGTA, HBED, TTHA, substituted EDTA or DTPA, DOTA and TETA. Claim 9 adds TITRA, TETRA and HMPAO derivatives, including compounds substituted with p-isothiocyanatophenylalkyl groups.

The radionuclide claims are unusually broad and cover imaging and therapeutic applications:

Claim	Radionuclide scope
11	Any detectable element complexed by the chelator
12	Alpha-, beta-, gamma- or positron-emitting radionuclides
13-14	Gamma-emitting radionuclides, including gallium-67, indium-111, technetium-99, ytterbium-169, yttrium-90 and rhenium-186
15-16	Alpha- or beta-emitting radionuclides, including astatine-211, bismuth-212, yttrium-90, copper-67, rhenium-186/188 and others
17	A specifically identified indium-111 compound and structure

Claim 14's classification of yttrium-90 and rhenium-186 among the listed gamma-emitting radionuclides appears inconsistent with their principal clinical use as beta emitters. The inconsistency does not necessarily invalidate the claim, but it creates a potential claim-construction and definiteness issue.

Does US Patent 5,776,894 cover OctreoScan?

OctreoScan is indium In-111 pentetreotide, commonly described as indium-111 DTPA-D-Phe-octreotide. The FDA approved OctreoScan in 1994 for scintigraphic localization of somatostatin-receptor-positive gastroenteropancreatic neuroendocrine tumors and associated lesions.[2]

The product is technically close to the patent's core disclosure:

Somatostatin analog: octreotide.
Chelator: DTPA derivative.
Attachment: N-terminal D-Phe amino group.
Detectable element: indium-111.
Use: imaging of somatostatin-receptor-positive tumors.

Claim 17 appears directed to an indium-111 complex corresponding to the commercial pentetreotide concept. The supplied transcription contains an image placeholder and the phrase “which is 111 In or,” so the precise claim syntax should be read from the issued patent document rather than the OCR text.

OctreoScan's commercial relevance was therefore closely aligned with the patent's claimed technology. That alignment no longer creates current patent risk because the patent term ended in 2015.[1]

What is the patent expiration date?

Event	Date or status
US patent issued	July 7, 1998
Statutory regime	Pre-URAA patent term, generally 17 years from grant
Expected expiration	July 7, 2015
Current status	Expired; no enforceable patent exclusion remains

The USPTO patent record identifies US 5,776,894 as expired based on expiration of the patent term.[1] Patent-term-adjustment, terminal-disclaimer and maintenance-fee records should be reviewed when reconstructing historical enforceability, but they do not restore the expired patent today.

No current freedom-to-operate analysis should treat US 5,776,894 as an enforceable US barrier. Later patents may still affect specific products, manufacturing processes or formulations.

What is the Orange Book status of US 5,776,894?

US Patent 5,776,894 is not a current Orange Book exclusivity asset. Orange Book listing applies to patents submitted for approved prescription drug products under the applicable FDA listing framework. A patent covering a radiopharmaceutical platform is not automatically listed, and historical listing status must be assessed against the relevant NDA and patent-submission record.[3]

For OctreoScan, the commercial product is an approved diagnostic radiopharmaceutical, but the patent's expired status eliminates any current Paragraph IV-based exclusion. A new abbreviated application or other regulatory pathway could face product-specific patents only if later patents were validly listed and unexpired.

When does OctreoScan lose exclusivity?

OctreoScan's regulatory exclusivity and the patent term are separate rights.

The FDA approved OctreoScan in 1994.[2] The patent term for US 5,776,894 ended in 2015.[1] Any FDA marketing exclusivity associated with the original approval ended many years earlier. The remaining commercial barriers are therefore regulatory, manufacturing and market-based rather than rights conferred by this patent.

A competing product would still need to satisfy radiopharmaceutical quality, sterility, radionuclide handling, labeling, pharmacokinetic and clinical requirements. A generic or follow-on product may also need to demonstrate pharmaceutical equivalence and bioequivalence, or use another FDA pathway depending on the product's regulatory classification.

Does the patent create Paragraph IV risk?

No current Paragraph IV risk arises from US 5,776,894 because the patent is expired. Paragraph IV certification is relevant when an applicant challenges an unexpired listed patent in connection with an ANDA. An expired patent cannot support a current 30-month stay or an ordinary patent-based launch prohibition.

Historical Paragraph IV activity involving OctreoScan cannot be inferred from the patent claims alone. The patent record establishes the patent's term, not whether a particular ANDA applicant filed a Paragraph IV certification or whether the parties executed a settlement.

What patent litigation and settlements affect this patent?

The supplied patent information does not establish a current infringement action, settlement or license involving US 5,776,894. The patent's expiration means that any historical litigation would have commercial significance only for past damages, launch timing or validity issues.

A litigation review should distinguish among:

Direct claims against an OctreoScan supplier.
ANDA litigation involving a listed patent.
Patent disputes over later DOTA or peptide analogs.
Manufacturing-process litigation.
License disputes involving commercial radiopharmaceutical rights.

The patent itself contains no manufacturing claims. Claims 1-17 are product claims, claim 18 is a composition claim, and claim 19 is a therapeutic method claim.

How does this patent compare with Lutathera patents?

Lutathera is lutetium Lu-177 dotatate, approved by FDA in 2018 for certain somatostatin-receptor-positive gastroenteropancreatic neuroendocrine tumors.[4] It uses a DOTA-based chelator and a somatostatin analog distinct from the indium-111 pentetreotide product used in OctreoScan.

Attribute	US 5,776,894 / OctreoScan	Lutathera
Primary product	Indium In-111 pentetreotide	Lutetium Lu-177 dotatate
Principal use	Diagnostic imaging	Peptide receptor radionuclide therapy
Chelator	DTPA derivative	DOTA
Radionuclide	In-111	Lu-177
Patent 5,776,894 status	Expired in 2015	Cannot block current Lutathera activity
Current risk source	Later product, process or formulation patents	Later composition, use, manufacturing and formulation patents

The expired patent may be relevant as prior art against later patent applications claiming broad DOTA-somatostatin platforms. It is not a current patent barrier to Lutathera or a competing Lu-177 product.

How strong is the patent estate?

The historical claim estate was strong in breadth but vulnerable at the edges.

Breadth

Claim 1 covers a wide combination of somatostatin peptides and N-terminal chelators. Claims 11-16 extend the platform across numerous detectable elements and therapeutic radionuclides. This structure could have supported infringement positions against products using the same N-terminal chelator architecture.

Potential validity pressure

The principal validity pressure points would have included:

Prior art involving radiolabeled somatostatin analogs.
Earlier DTPA-peptide conjugates.
Broad genus claims covering many peptide sequences and chelators.
Enablement across multiple radionuclides and chelator classes.
Written-description support for the full sequence and substituent scope.
Ambiguity in radionuclide categorization.
Claim 19's broad tumor-treatment language.

These issues matter historically. They do not affect present enforceability after expiration.

What generic launch scenarios exist?

A competitor could pursue several commercial strategies:

Launch scenario	Patent position
Indium-111 DTPA-octreotide imaging agent	No blocking right from US 5,776,894
Alternative indium-labeled somatostatin analog	Patent 5,776,894 expired; assess later patents
Lu-177 DOTA peptide therapy	Outside the expired patent's practical enforcement period; assess newer estates
Ga-68 PET somatostatin agent	No current risk from this patent; evaluate newer chelator and kit patents
Alpha-emitting somatostatin therapy	Claims 12, 15 and 16 are historically relevant but expired
Non-N-terminal or side-chain conjugate	May avoid literal claim 1 even before expiration

The main post-expiration barriers are FDA approval, radionuclide supply, peptide manufacturing, chelator conjugation, radiolabeling validation, sterile production and distribution infrastructure.

What manufacturing and geographic IP barriers remain?

US Patent 5,776,894 has no current US enforcement value. It also does not automatically determine rights in Europe, Japan, Canada or other jurisdictions. Foreign family members must be assessed separately for filing, grant, lapse and expiration dates.

For a current product, the relevant patent search should include:

DOTA, DTPA and NOTA conjugation chemistry.
Solid-phase peptide synthesis and cyclization.
Radiolabeling kits and precursor formulations.
Lu-177, Ga-68, Cu-64 and Pb-212 complexes.
Stabilizers, buffers and injectable formulations.
Methods for treating specific tumor types.
Manufacturing processes and radionuclide purification.
Device, kit and dose-calibration claims.

The expired patent remains important as prior art in those searches, particularly for broad claims directed to N-terminal chelator attachment and radiolabeled somatostatin-receptor ligands.

Key Takeaways

US Patent 5,776,894 covers N-terminal chelator-linked somatostatin peptides, radiometal complexes, compositions and tumor-treatment methods.
Its commercial center of gravity is the indium-111 DTPA-octreotide technology associated with OctreoScan.
The patent issued July 7, 1998 and expired July 7, 2015 under the applicable 17-year-from-grant term.
It creates no current Paragraph IV, Orange Book or infringement barrier.
Claims 1 and 11-16 are broad platform claims, while claims 5-10 and 17 narrow the scope to defined peptide and radiolabel structures.
Lutathera and newer Ga-68, Lu-177 and alpha-emitting products require analysis of later patents, not reliance on this expired patent.
The patent has continuing prior-art value for validity and freedom-to-operate reviews involving radiolabeled somatostatin peptides.

FAQs

Does US Patent 5,776,894 still block indium-111 pentetreotide?

No. The patent expired in 2015 and cannot currently block manufacture, use or sale in the United States.

Is DOTA-somatostatin technology covered by this expired patent?

Some DOTA-linked compounds may have fallen within the broad historical language of claims 1, 7, 8 or 11. The patent's expiration means that the question has prior-art significance rather than current enforcement significance.

Can a company launch a generic OctreoScan product without addressing this patent?

Yes, US Patent 5,776,894 is expired. The applicant must still satisfy applicable FDA requirements and clear any later, unexpired patents.

Does claim 19 cover only cancer treatment?

Claim 19 is directed to in vivo treatment of somatostatin-receptor-positive tumors and metastases using alpha- or beta-emitting complexes. It does not cover diagnostic imaging alone.

Are European counterparts still enforceable?

No enforceable European right can be determined from the US patent record alone. Each foreign family member requires a separate jurisdiction-by-jurisdiction status review.

References

United States Patent and Trademark Office. (1998). US Patent No. 5,776,894, patent term and bibliographic record. USPTO Patent Center and Patent Examination Data System.
U.S. Food and Drug Administration. (1994). OctreoScan (indium In-111 pentetreotide) injection prescribing information. FDA.
U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Food and Drug Administration. (2018). Lutathera (lutetium Lu 177 dotatate) injection prescribing information. FDA.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8828364	Dec 05, 1988
United Kingdom	8916115	Jul 13, 1989
United Kingdom	8916761	Jul 21, 1989
United Kingdom	9111199	May 23, 1991

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	403476	⤷ Start Trial
Austria	A901789	⤷ Start Trial
Australia	4587189	⤷ Start Trial
Australia	633859	⤷ Start Trial
Belgium	1002296	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,776,894

Summary for Patent: 5,776,894